AUTOMOBILE TIRE HYDROPLANING -

A STUDY OF WHEEL SPIN-DOWN

AND OTHER VARIABLES.

by

A. J. Stocker Associate Research Engineer

J. T. Dotson Research Associate

and

D. L. Ivey Research Engineer

Research Report Number 147-3F

Variables Associated with Hydroplaning Research Study Number 2-10-70-147

Sponsored by

The Texas Highway Department In Cooperation With The

U. S. Department of Transportation Federal Highway Administration

August 1974

TEXAS TRANSPORTATION INSTITUTE Texas A&M University

College Station, Texas

1ecnnleal Reports Cant~r · TWtaS Tra~ 'rstiMe

HCHNICAL REPORT STANOARD TITLF PAGI

1. R"port No, 2. Government Aceession No. 3. Recipient's Catalog No.

4. Title and Subtitle 5, Report Dote

AUTOMOBILE TIRE HYDROPLANING - A STUDY OF WHEEL August 1974 SPIN-DOWN AND OTHER VARIABLES 6. Performing Organization Code

7, Author/ s) 8. Performing Organization Report No.

A. J. Stocker, J. T. Dotson, and D. L. Ivey Research Report 147-3F

9. Performing Organization Nome and Address 10. Work Unit No.

Texas Transportation Institute Texas A&M University 11. Contract or Grant No.

College Station, Texas 77843 Research Study 2-10-70-147 13. Type of Raport and Period Covered

12. Sponsoring Agency Nome and Address Final Report - September 19 9 Texas Highway Department August 1974 11th and Brazos Austin, Texas 78701 14. Sp-::ansoring Agency Code

I 5. Supplementary Notes Research performed in cooperation with DOT, FHWA. Research Study Title: "Variables Associated with Hydroplaning."

.. 16

. Ab"••c•A study of the wet weather characteristics of five different pavements and ten different tires is presented. The pavements studied were a portland cement concrete, a seal coat surface treatment, a hot mix asphalt, a jennite surface and a longitudinally grooved portland cement concrete. The tires studied were several bias ply tires with different tread depths, a wide tire with full tread, a test standard tire, a smooth fiberglass belted tire and a full tread steel belted radial. In this study, wheel spin-down was used as the criterion for the detection of hydroplaning and the variables considered were tire tread depth, tire inflation pressure, water depth and wheel 1 oad. A sloping trough 800 ft. long, 30 in. wide and 4 in. deep was used in obtaining the data. The results indicate that the sea 1 coat surface treatment requires a considerably higher ground speed to cause spin-down than do the other pavements tested. It was also observed that no single critical speed, necessary for wheel spin-down to occur, exists for the range of variables selected, but it is recommended that there be a reduction of speed to 50 mph for any section of highway on which water can accumulate to 0.1 inch or more during wet weather periods.

17. Key w .. d, highways, pavements, water dept hl~. Distribution Statement

hydroplaning, spin-down, surface tex-ture, tire inflation pressure, tire / tread depth, grooved pavements.

19. ·-Security Clouil. {of this report) 20. Security Cloaaif. {of this page) 21. No. of Pages 22. Price

Unclassified Unclassified 116

·-Form DOT F 1700.7 1&•691

TTI-2-10-70-147-3F

ERRATA SHEET

for

Research Report 147-3F, "Auto!l'obile Hydroplaning--A Study of Wheel Spin-Down and Other Variables," by A. J. Stocker, J. T. [lotson, and D. L. Ivey, Texas Transportation Institute, Colleqe Station, Texas.

Pa9e 30

wrong: d = 3.38 X 103 TO.ll L0.43 ro.sg

S0.42

correct: d = 3.38 X 10-3 To. 11 L 0.43 r0.59 s0.42

wrong: d = Water depth in inches

correct: d = Average water depth above top of texture in

wrong: S = Cross slope in in./ft.

correct: S = Cross slope in ft./ft.

inches

j j j j j j j j j j j j j j j j j j j j

j j j j j j j j j j

j j j j j

j j j

j

j j j

TABLE OF CONTENTS

ACKNOWLEDGEMENTS

DISCLAIMER

ABSTRACT

SUMI~ARY

IMPLEMENTATION

I. INTRODUCTION . . . . . . II. REVIEW OF THE LITERATURE

III. SELECTION OF PARAMETERS

IV. EXPERIMENTATION . . .

v. DISCUSSION OF RESULTS

VI. APPLICABILITY TO SAFE WET WEATHER SPEEDS.

VII. CONCLUSIONS . . . .

REFERENCES . . . . . . . . . . . . . . . . . . . . . . . .

ii

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I LIST OF FIGURES

1. The Hydroplaning Trough ..... . . . . . . . . . . . 2. Typical Water Depth Reading Taken Before

Test on Hydroplaning Trough ...

3. Tow Truck and Instrumented Test Trailer

4. Typical Test Run on Hydroplaning Trough

5. Effect of Vehicle Ground Speed on Wheel Spin-Down for

Concrete Pavement -Tire No. 4 - WD = 0.25 in . 6. Effect of Vehicle Ground Speed on Wheel Spin-Down for

Concrete Pavement - Tire No. 4 - WD = 0.40 in . 7. Effect of Vehicle Ground Speed on Wheel Spin-Down for

Concrete Pavement -Tire No. 8 - WD = 0.40 in . 8. Effect of Vehicle Ground Speed on Wheel Spin-Down for

Concrete Pavement - Tire No. 8 - WD = 0.70 in . . 9. Effect of Vehicle Ground Speed on Wheel Spin-Down for

. . .

. . .

. . . .

. . .

14

14

15

15

39

40

41

42

Seal Coat Surface Treatment -Tire No. 4 - WD = 0.40 in . . . . 43

10. Effect of Vehicle Ground Speed on Wheel Spin-Down for

Seal Coat Surface Treatment - Tire No. 4 - WD = 0.70 in . . . . 44

11. Effect of Vehicle Ground Speed on Wheel Spin-Down for

Seal Coat Surface Treatment -Tire No. 8 - WD = 0.40 in

12. Effect of Vehicle Ground Speed on Wheel Spin-Down for

Seal Coat Surface Treatment - Tire No. 8 - WD = 0.70 in

13. Effect of Vehicle Ground Speed on Wheel Spin-Down for

Hot Mix Pavement - Tire No. 4 - 0.40 in

14. Effect of Vehicle Ground Speed on Wheel Spin-Down for

Hot Mix Pavement - Tire No. 7 - 0.40 in

iii

45

46

47

48

LIST OF FIGURES (cont'd)

15. Effect of Vehicle Ground Speed on Wheel Spin-Down for

Hot Mix Pavement - Tire No. 8 - WD = 0.33 in . . . . . . . . 49

16. Effect of Vehicle Ground Speed on Wheel Spin-Down for

Jennite Pavement - Tire No. 4 - WD = 0.33 in . . . . . . 50

17. Effect of Vehicle Ground Speed on Wheel Spin-Down for

Jennite Pavement - Tire No. 4 - WD = 0.40 in . . . . . . . . 51

18. Effect of Vehicle Ground Speed on Wheel Spin-Down for

Jennite Pavement - Tire No. 8 - WD = 0.40 in . . . . . . . 52

19. Effect of Vehicle Ground Speed on Wheel Spin-Down

for Longitudinally Grooved Concrete Pavement -

Tire No. 1 - WD = 0.40 in. . . . . . . . 53 !. 1 " t 20. Effect of Vehicle Ground Speed on Wheel Spin-Down I

for Longitudinally Grooved Concrete Pavement 1 i

Tire No. 3 - WD = 0.40 in. . . . . . . . . . . . . 54 I 21. Effect of Vehicle Ground Speed on Wheel Spin-Down f

I for Longitudinally Grooved Concrete Pavement -I I

Tire No. 4 - WD = 0.40 in. 55 ' . . . . . . . . ' . ' " '·' 22. Effect of Vehicle Ground Speed on Hheel Spin-Down J

H '

for Longitudinally Grooved Concrete Pavement -

Tire No. 4 - WD = 0.25 in. . . . . . . . . . . 56

23. Effect of Vehicre Ground Speed on ~lhee 1 Spin-Down

for Longitudinally Grooved Concrete Pavement -

Tire No. 9 - WD = 0.33 in. . . . . . . . . . . . . . . 57

iv

-

LIST OF FIGURES (cont'd)

24. Effect of Vehicle Ground Speed on Hheel Spin-Down

for Longitudinally Grooved Concrete Pavement -

Tire No. 10 - WD = 0.40 in. . . . . . . .

25. Comparison of Experimental Results to NASA Equation

for Concrete Pavement - Tire No. 7 - WD = 0.40 in .

26. Comparison of Experimental Results to NASA Equation

for Concrete Pavement - Tire No. 8 - WD = 0.40 in .

27. Comparison of Experimental Results to NASA Equation

for Concrete Pavement - Tire No. 5 - WD = 0.40 in .

. . . .

28. Comparison of Experimental Results to NASA Equation for

Seal Coat Surface Treatment- Tire.No. 4 - WD = 0.70 in

29. Comparison of Experimental Results to NASA Equation for

Seal Coat Surface Treatment - Tire No. 8 - WD = 0.70 in

30. Comparison of Experimental Results to NASA Equation

for Hot Mix Pavement - Tire No. 2 - WD = 0.40 in ..

31. Comparison of Experimental Results to NASA Equation

for Hot Mix Pavement - Tire No. 4 - WD = 0.40 in ..

32. Comparison of Experimental Results to NASA Equation

for Hot Mix Pavement - Tire No. 7 - WD = 0.40 in.

33. Comparison of Experimental Results to NASA Equation

for Hot Mix Pavement -Tire No. 7 - WD = 0.33 in ..

34. Comparison of Experimental Results to NASA Equation

for Jennite Pavement - Tire No. 4 - WD = 0.40 in ..

35. Comparison of Experimental Results to NASA Equation

for Jennite Pavement -Tire No. 5 - WD = 0.40 in ..

v

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58

59

60

61

62

63

64

65

66

67

68

69

LIST OF FIGURES (cont'd)

36. Comparison of Experimental Results with NASA Equation

for Jennite Pavement -Tire No. 5 - ~JD = 0.33 in .•

37. Comparison of Experimental Results to NASA Equation

for Longitudinally Grooved Concrete Pavement -

Tire No. 9 - WD = 0. 25 in.. . . . .

38. Comparison of Experimental Results to NASA Equation

for Longitudinally Grooved Concrete Pavement-

Tire No. 9 - WD = 0.40 in .....

39. Comparison of Experimental Results to NASA Equation

for Longitudinally Grooved Concrete Pavement -

Tire No. 4 - WD = 0.40 in ••.

40. Effect of Water Depth and Wheel Load on Ground Speed

to Cause 10% Spin-Down - Tire No. 8 . • • . . . . . •

41. Effect of Water Depth and Wheel Load on Ground Speed

to Cause 10% Spin-Down - Tire No. 7 ....

42. Effect of Water Depth and Tire Aspect Ratio on Speed

to Cause 10% Spin-Down - Pavement No. 1 ..

43. Effect of Water Depth and Tread Depth on Speed to

Cause 10% Spin-Down - Pavement No. 1

44. Effect of Water Depth on Speed to Cause 10% Spin-Down-

Hot Mix Pavement - Tire No. 1 . . . . . . . 45. Effect of \~ater Depth on Speed to Cause 10% Spin-Down~

Hot Mix Pavement - Tire No. 3 . . . . . . 46. Effect of Hater Depth on Speed to Cause 10% Spin-Down

Jennite Pavement - Tire No. 1 . . . . .

vi

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73

74

75

. . . . . 76

. . • . 77

. . 78

. . 79

-. . . 80

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LIST OF FIGURES (cont'd)

47. Effect of Water Depth on Speed to Cause 10% Soin-Down -

Longi tudi na lly Grooved Concrete Pavement - Tire No. 4

48. Effect of Water Depth on Speed to Cause 10% Spin-Down -

Longitudinally Grooved Concrete Pavement - Tire No. 9

49. Repeatability Check of Data for Jennite Pavement -

Tire No. 3 - WD = 0.33 in . . . . ..

50. Repeatability Check of Data for Concrete Pavement -

Tire No. 1 - WD = 0.33 in .

51.

. . . . Comparison of Concrete and Seal Coat Surface

Treatment - Tire No. 1 . . . . . . . 52. Comparison of Concrete and Seal Coat Surface

Treatment - Tire No. 4 . . . . . . . . . . . . . . 53. Comparison of Concrete and Hot ~li x Pavements -

Tire No. 4 . . . . . . . . . . . . . . . . . 54. Comparison of Hot Mix and Jennite Pavements -

Tire No. 3 . . . . . . . 55. 10% Spin-Down for Two Tires and Three Surfaces at

Selected Tire Pressures - Tire No. 9 and 10 .. . . . . . 56. Effect of Surface and Tire Pressure and Ground

Speed for 10% Spin-Down - Tire No. 4

57. Comparison of Bias Ply Tires Tested (l ,5,7)

58. Comparison of Belted Tires Tested (9,10)

59. Comparison of Ungrooved and Grooved Concrete Surfaces

With Various Water Depths - Tire No. 4

60. Effect of Water Depth on Grooved Concrete Surface

vii

81

82

83

84

85

86

87

88

89

90

91

92

93

94

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LIST OF FIGURES (cont'd) I l I

95 i I

61. Comparison of Ungrooved Concrete, Grooved Concrete and

Seal Coat Surfaces - Tire No. 9 .

62. Effect of Texture on Hydroplaning Tire No. 8 96 I w

97 I 63. Effect of Texture on Hydroplaning - Tire No. 4

64. Effect of Pressure on Hydroplaning - Tire No. 4 98

65. Effect of Tire on Hydroplaning - Tire 4, 7 and 8 99

66. Comparison of Tire Pressures - Accident Study .. 100

67. Combinations of Cross Slope and Texture Required To

Prevent Significant Water Depths 101

viii

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ACKNOl~LEDGEMENTS

These tests and evaluations were conducted on Study No. 2-8-70-147

(HPR-1 (10)), "Vari.ables Associated With Hydroplaning," sponsored by the

Texas Highway Department in cooperation with the U. S. Department of

Transportation, Federal Highway Administration.

DISCLAIMER

The contents of this report reflect the views of the authors who are

responsible for the facts and the accuracy of the data presented herein.

The contents do not necessarily reflect the official views or policies of

the Federal Highway Administration. This report does not constitute a

standard, specification or regulation.

ix

ABSTRACT

A study of the wet weather characteristics of five different pavements

and ten different tires is presented. The pavements studied were a

portland cement concrete, a seal coat surface treatment, a hot mix asphalt,

a jennite surface and a longitudinally grooved portland cement concrete.

The tires studied were several bias ply tires with different tread depths,

a wide tire with full tread, a test standard tire, a smooth fiberglass

belted tire and a full tread steel belted radial. In this study, ~1heel

spin-down was used as the criterion for th.e detection of hydroplaning

and the variables considered were tire tread depth, tire inflation pressure,

water depth and wheel load. A sloping trough 800 ft. long, 30 in. wide

and 4 in. deep was used in obtaining the data. The results indicate that

the seal coat surface treatment requires a considerably higher ground speed

to cause spin-down than do the other pavements tested. It was also observed

that no single critical speed, necessary for wheel spin-down to occur,

exists for the range of variables selected, but it is recommended that

there be a reduction of speed to 50 mph for any section of highway on which

water can accumulate to 0.1 inch or more during wet weather periods.

Key Words: highways, pavements, hydroplaning, spin-down, surface texture,

water depth, tire inflation pressure, tire tread depth,

grooved pavements.

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SUMMARY

Vehicles operating on wet pavements suffer impairment of their steering

and braking capabilities. Tests have shown that this condition deteriorates

as the vehicle speed increases, and at a critical ground speed the vehicular

wheel is separated from the pavement by a layer of fluid and is said to be

hydroplaning. When this occurs the steering ability of the vehicle is

completely lost and the braking capability is greatly diminished.

The spin-down (reduction in wheel speed) of a wheel is an indication

of a loss in the tire-ground frictional force and is regarded as a mani­

festation of hydroplaning. Spin-down occurs when the hydrodynamic lift

effects combine to cause a moment which opposes the normal rolling action

of the tire caused by the drag forces. As ground speed increases, the tire

footprint becomes detached from the pavement which decreases the ground

friction on the tire. This report uses wheel spin-down as a criterion for

evaluating the wet weather properties of several pavements and considers

the effects of water depth, tire inflation pressure, tire tread depth and

wheel load on the vehicle speed necessary to cause spin-down. The study

was performed by conducting full-scale tests in a hydroplaning trough

800 ft. long, 30 in. wide and 4 in. deep. Water depths up to 0.8 in. can

be maintained in the trough.

The most significant findings based on the assumption that spin-down

greater than 10% causes a sufficient reduction in the frictional coefficient

so that vehicle stability is affected may be stated as follows:

1. A high macrotexture pavement which allows water to escape

from under the tire requires a considerably higher ground

I xi 18: ......................... ________________ __

speed to cause spin-down than a low macrotexture pavement.

Consequently, a safer condition is created.

2. Decreasing the tire inflation pressure normally has the

effect of lowering the ground speed at which a certain

amount of spin-down occurs. Thus, a less safe condition

is created.

3. Increasing the width of a tire causes a decrease in the

ground speed required to produce spin-down.

4. An increase in the water depth causes a decrease in the

speed at which spin-down takes place.

5. A reduction in tire tread depth causes a decrease in the

speed at which spin-down takes place.

xii

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IMPLEMENTATION

Hydroplaning is the culmination of conditions leading to loss of tire

pavement friction on the highway. The primary causes are water on the pave­

ment surface and high vehicle speeds. Since this end point in available

friction deterioration can be absolute, meaning total loss of contact with

the road surface and thus total loss of control, it must be systematically

avoided. The findings of this study concerning the influences of the road,

the automobile and the driver can be implemented in the following ways.

1. By adopting the objective that pavement cross slopes, surface

textures and drainage path lengths will be designed, con­

structed and maintained so that significant water depths

on roadway surfaces will be extremely rare occurrences.

Figure 67 shows appropriate combinations of these inter­

acting factors for a suggested design rainfall of one inch

per hour, an intensity that will not be exceeded 99.95%

the time in Texas.

2. By using the anti-hydroplaning criteria presented as a

justification for the resurfacing of highways which have

rutted water holding wheel paths, insufficient cross

slope (due to poor construction practice or to substrate

movement) or insufficient surface texture.

3. By using the findings of this study concerning proper

vehicle maintenance and driver performance in public

information documents, films and training schools.

These findings include:

a. The need to maintain high tire pressures.

xiii

b. The need to maintain deep tire tread depths.

c. The need to reduce vehicle speed.

d. The way to determine visually whether a hazardous highway surface condition exists.

4. By the use of specific data which determines critical

hydroplaning speeds to justify wet weather speed limits

as interim measures at sites determined to be hazardous

during rainfall.

xiv

f ,,

I. INTRODUCTION

As a vehicle travels along the highway, the friction required to

perform maneuvers is developed at the tire-pavement interface. The

friction developed will depend on such things as the pavement texture,

tire configuration, area of the contact zone, tread design, speed and

tire pressure. If this area is contaminated, the friction developed

at the interface will be decreased. If the contaminant is water, the

possibility of hydroplaning exists.

Hydroplaning is caused by the build up of fluid pressures within the

tire-pavement contact zone, and hydroplaning is considered to exist when

the hydrodynamic uplift equals the downward force exerted on the wheel.

At this point the tire is completely supported by the water layer. When

in this condition, the tire has lost all contact with the pavement sur­

face and thus has lost the tractive force necessary to perform normal or

emergency driving maneuvers.

This study has chosen to use wheel spin-down as the indicator of

tire hydroplaning. Spin-down is a term describing the loss of angular

velocity of a wheel traveling over a flooded pavement as the speed of the

vehicle remains constant or increases. Wheel spin-down is caused by the

build up of hydrodynamic pressure in the forward portion of the tire­

pavement contact area. This force acts to oppose the normal rotating

action of the tire and can build up to a point to cause the tire to stop

rotation completely. It has been assumed that once spin-down has been

initiated some loss of tire-pavement contact has occurred. Once a portion

of the contact is lost, the friction developed between the tire and the

pavement is decreased and a potentially dangerous situation exists.

1

The factors being considered in this study are water depth, pavement

texture (primarily macrotexture), vehicle speed, wheel load, tire inflation

pressure, tire configuration and tire tread depth. By adjusting each of

the variables, the effect each has on the speed at which a certain amount

of spin-down occurs. can be observed.

Up to this time most research in this area has been done by the

aircraft industry at the high speeds involved with take-off and touch­

down. Because of this, the research has been done using aircraft tires

which have very different characteristics from automobile tires. It is

the objective of this study to observe what occurs at lower speeds, wheel

load and tire inflation pressure.

2

II. REVIEW OF THE LITERATURE

Theoretical and experimental studies have been made by a number

of researchers. The works more nearly associated with the research

investigation presented in this report and reviewed during the course

of the study are listed in references 1-52·.

Saal (42) initially studied the problem in 1935 and developed a

model based on two planes approaching each other in a fluid. He

assumed the tire contact area to be elliptical and used Reynold's

equation to obtain his results. r~oore (40) used squeeze film theory

to analyze the problem and concluded that the molecular mechanism of

viscosity that would be encountered between tire and wet pavement requires

further study. Also, he feels that the Reynolds-Stefan equation is

inadequate to describe this phenomenon.

Horne and Dreher (27) derived an equation to predict the critical

speed at which total hydroplaning begins. This equation assumes the

load on the tire to be in equilibrium with the dynamic pressure in front

of the tire and neglects the effects of fluid depth. For an experimentally

determined lift coefficient of 0.7, Horne develops the equation

where

vcr = 10.35 1P

Vcr =total hydroplaning speed in statute mph, and

p = tire inflation pressure in psi.

( 1 )

This equation is limited to smooth tires or commercially treaded tires

whose tread depth is less than the water film thickness. Reference 27

indicates that the results predicted by Eq. 1 are in reasonable agreement

3

------~~--------.......................... ~ .. with experimental data obtained for a variety of tires subjected to

different loads and inflation pressures.

Gengenbach (19) developed an empirical equation which includes the

thickness of the water film and his correlation with test results sho~1ed

that the total hydroplaning speed was signifi.cantly affected by the water

film thickness. This contradicted the equation developed by Horne (27).

Gengenbach's equation, like Horne's (27) assumed that the wheel load and

dynamic pressure were in equilibrium but used the cross section of the

water film under the tire ·contact patch perpendicular to the surface

velocity as the area for the force calculation. The area was multiplied

by a lift coefficient and the equation to predict the total hydroplaning

speed.was derived as

where

v = 508

V = total hydroplaning speed in km/hour,

Q =wheel load in KP(lKP = 2.2 lb.),

B = maximum width of contact patch in mm,

t = thickness of water film in mm, and

CL= lift coefficient determined empirically for a particular tire.

Gengenbach concludes that grooving of the tires considerably reduces the

lift coefficient and thus increases the critical hydroplaning_ speed. In

his work, tire designs with rna i nly ci rcumferenti a 1 grooves achieved CL

reductions of nearly 50% whereas designs with grooves primarily oriented

in the lateral direction achieved reductions down to 25% of the smooth tires.

4

r

ires.

Martin (35) explains the tire hydroplaning phenomenon from the stand­

point of theoretical hydrodynamics and then compares theoretical and

experimental results. From the study it is concluded that for moderate

water depths and grooved tires, the lift coefficient for incipient

hydroplaning does not vary appreciably. Also, an inviscid fluid may be

assumed except for the case of smooth tires and/or thin films of water.

Dugoff and Ehrlich (13) studied the hydroplaning problem through scale

model laboratory experiments and employed dimensional analysis principles

to interpret their results. The tests were conducted for smooth tires of

rectangular cross-section at various loads and water depths. The authors

interpret Eq. 1 presented in ref. 27 in terms of dimensional analysis

principles and indicate that neither fluid gravity forces nor viscosity

forces had an appreciable influence on the full-scale tests that were

used in the comparison of Eq. 1 and presented in ref. 27. Further, the

authors of ref. (13) recommend that the effects of configurational and

tread changes to tires and the partial hydroplaning problems be studied.

Wray and Jurkat (50) derived an empirical equation relating critical

hydroplaning speed, water film thickness and nominal contact patch bearing

pressure for 811 diameter polyurethane model tires having four different

widths and a smooth surface. The results obtained using their equation

were compared to those obtained by Horne's equation {Eq. 1). They noted

that Horne's equation was bracketed by lines of constant water film thickness

having nearly the same slope. This implies.that by selecting a certain water

depth, Horne's NASA equation can be duplicated with experimental data frorr

the model wheel.

A vast amount of research concerning friction characteristics and

5

effects of the pavement texture and material has been conducted by British

researchers (1,2,4,17,18,22,23,36). Allbert (1) discusses the effects of

tire design parameters on hydroplaning and concludes that the most important

is the geometric design of the tread pattern. Allbert, Walker and Maycock (2),

after investigating various tires and pavement surfaces, conclude that the

coefficient of friction for a slipping tire is significantly decreased with

an increase in speed on fine-textured surfaces and to a lesser extent on

coarse-textured surfaces. Further, the tread pattern did not play as

significant a role on the coarse-textured surfaces. This implies that

tread wear would have a minor effect on coarse-textured surfaces. Gough

and Badger (22) discuss the effect of tread design on various surfaces

and the hydroplaning of heavy vehicles fitted with smooth tires which are

traveling on flooded road surfaces. Their findings on pavement surfaces

are similar to those presented in ref. 2. Martin (36) discusses treatments

to existing concrete and asphalt surfaces in order to improve their skidding

resistance. The materials and methods which may be used in future construc­

tion are also described and illustrated.

A large amount of research concerning the variables associated with

hydroplaning and particularly pavement texture has also been conducted by

American investigators (5,11,14,28,30,33,34,43,51 ,52). Beaton, Zube and

Skog (5) conducted studies on the effect of pavement grooving to reduce

wet weather accidents. Their results indicate that pavement grooving

parallel to the centerline enhances the wet weather behavior of concrete

pavements and the friction value is raised. DeVinney (11) investigated

the effects of the tread design and compound, tire construction and road

surface on the hydroplaning problem. He concluded that the vehicle operating

6

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speed is the most significant single factor affecting wet skid resistance.

Also, a coarse textured surface has the greatest effect on decreasing the

significance of speed; tread design, tread compound, tire construction,

surface and temperature all play a role with the effects on skid resistance.

Horne (28) from his investigation of tires and pavements concluded that

tires having smooth or badly worn treads, and pavements that are worn

from heavy traffic or possess too little surface texture, are hazardous.

Yager (51) discusses the types of tire traction losses on wet roads and the

effects of pavement surface contaminants, surface texture, tire tread

design and ground speed on pneumatic tire braking and steering capability.

From his study, the author concludes that pavement grooving, both trans­

versely and longitudinally, is an effective means for reducing all known

phenomena associated with low tire-surface friction. In addition,

badly worn tires indicated a significant reduction in the vehicular

braking and steering characteristics when compared with new full tread

tires.

7

III. SELECTION OF PARAMETERS

Pavements

Five pavements have been selected for this study. The first pavement

studied was a burlap drag finish concrete.surface with an average surface

texture of 0.018 in. as measured by the silicone putty method. This pave­

ment was considered_ to be typical or similar to concrete pavements presently

in use. The second pavement tested was a seal coat surface treatment with

rounded river gravel, stone size between -5/8 in. and+ No.4 sieve used

as cover stone. The average texture of this surface was 0.146 in. measured

by the silicone putty method. This high texture composed of fairly loosely

bound aggregate is obviously impractical for use on high speed roadways but

was chosen simply to show the effect of increasing the macrotexture. A hot

mix asphalt was used as the third pavement. An average texture of 0.033 in.

was measured by the silicone putty method. This pavement was chosen as one

that was similar to those presently in use. The fourth pavement tested was

a clay filled coal-tar emulsion surface (Jennite). This surface had a

texture of 0.020 in. as measured by the silicone putty method. This surface

was chosen because it was felt that it was similar to a bleeding asphalt

pavement or a worn wheel rut. The fifth and final surface tested was the

initial burlap drag finish portland cement concrete modified by longitudinal

grooves 0.125 in. deep by 0.125 in. wide on 1.0 in. centers. This surface

was chosen because of the increased use of grooving on public highways.

The surface texture was 0.047 as measured by the silicone putty method.

It should be noted that by measuring the texture by use of the silicJne

putty method only the macro-texture is indicated. It is impossible to

8

show the magnitude of the micro-texture when using this method. This is

shown by the fact that pavement four, the jennite surface, has a higher

texture than the concrete pavement, surface one. The concrete pavement

has a very gritty feeling texture while the jennite is smooth~ It is felt

that microtexture plays an important part in the reduction of hydroplaning

but no quantitive measure of its effect was made in this study. It is

possible however to make inferences from the data obtained.

vlater Depths

Various water depths, measured from the top of the surface asperities,

were considered and values were selected so that the influence of this vari­

able could be evaluated. The water depths studied on the concrete surface

varied from 0.12 to 0.70 in. This is a very wide range, with the upper limit

being rather impractical, but studied to see just how much effect the water

depth had on spin-down and if there was a point past which it had no effect.

The depths selected for the seal coat surface varied from 0.25 in. to 0.70 in.

This range was considered because when using water depths below 0.25 in. on

this particular surface it was extremely difficult to obtain any data, the

main reason being that the speeds necessary to cause spin-down at the lower

water depths were not achievable with the test vehicle. On the third and

fourth surfaces the water depth was varied from 0.12 to 0.40 in. On the

fifth surface the water depth was varied from 0.18 in. to 0.40 in. It was

found that this is a more realistic range of water depths and that there

were ample data produced· using these values.

Tire Inflation Pressures

Tire inflation pressures varying from 18 psi to 36 psi in 6 psi

increments were selected for evaluation on all five pavements. This range

9

, '

ri-

I mit

er

ct.

0 in.

on

e

!er

's

e

of values was not only representative of pressures found in the tires

of most ground vehicles, but also provides an adequate variation or range

for studying the effect of the variable. Pressures higher than 36 psi

were not selected because the tow vehicle was unable to attain speeds high

enough to produce meaningful data.

Wheel Load

Wheel loads of 800 lb. and 1,085 lb. were selected for evaluation on

the concrete pavement. The load of 1,085 lb. was used as the basic test

weight. This was done because of its specification as the ASTM skid trailer

standard. The 800 lb. load was used on tires No. 7 and 8 tested on the

concrete surface. This weight was chosen because it provided enough varia­

tion to observe the effect of this parameter. Only the 1,085 lb. load was

used when testing the other four surfaces since no appreciable variation in

the results was observed in the evaluation of the concrete pavement when the

800 lb. was used.

Tires

Ten tires were selected for the study. They included:

1. Manufacturer A 7.75-14 Bias Ply - Full Tread Depth

2. Manufacturer A 7.75-14 Bias Ply - l/2 Tread Depth

3. Manufacturer A 7.75-14 Bias Ply - Smooth

4. Manufacturer B F70-l4 Wide Tire - Full Tread Depth'

5. Manufacturer C 7.75-14 Bias Ply- Full Tread Depth

6. ASTM E-17 Traction Standard 7.50-14 - Full Tread Derth

7. Manufacturer D 7.75-14 Bias Ply - Full Tread Depth

8. Manufacturer E 7.75-14 Bias Ply - Smooth

10

9. Manufacturer E

10. Manufacturer F

F78-14 Glass Belted - Smooth

195-14 Steel Belted Radial - Full Tread Depth

It was felt that this wide range of tires would provide an adequate

eva 1 uati on of the effects of tire geometry, stiffness and tread depth.

11

Joth

11 th

IV. EXPERIMENTATION

The tests were conducted in a sloped trough (0.88'/100') 800ft. long,

30 in. wide and 4 in. deep which is shown in Figure 1. The construction

procedures and specifications for this facility can be found in reference 46.

Because of its configuration and water supply, there was no difficulty

encountered in obtaining water depths of 0.7 in. above the pavement

·asperities. Even though a perfectly level surface was desired, variations

in the trough existed. Therefore, in order to better interpret the data,

water depths were taken at several points in the trough as shown in Figure

2. The variation of water depths was most pronounced for the seal coat surface.

It is difficult to obtain constant conditions when performing tests in

the open. Therefore, the data contain the influence of temperature and

varying winds. Experimentation was halted whenever wind speed was greater

than 15 mph. It was felt that this would cause variations in the water depth

that would affect the data. It has been observed that wind speed below this

point did not affect the data.

The tow vehicle and instrumented test trailer are shown in Figure 3

and a photograph of a typical test is shown in Figure 4. As can be seen

from these photographs, the tow vehicle is positioned so as to straddle

the trough while the test trailer is offset so that the left tire of the

trailer is positioned in the trough. The ground speed from the fifth

wheel and the speed of the test wheel in the trough are sensed by identiccl

tachometer generators. The output from the generators is fed into a

Hewlett-Packard 320 recorder which contains its own amplifier circuits.

The two wheel speeds are simultaneously recorded as analog traces on a

strip chart. From this chart the two ground speeds can be compared and

12

the percent spin-down calculated. The fifth wheel or vehicle speed is

also displayed to the driver on a digital voltmeter.

13

Figure 1. The Hydroplaning Trough.

Figure 2. Typical Water Depth Reading Taken Before Test on Hydroplaning Trough.

14

Figure 3. Tow Truck and Instrumented Test Trailer.

Figure 4. Typical Test Run on Hydroplaning Trough.

15

V. DISCUSSION OF RESULTS

As defined by Horne (27), the critical hydroplaning speed is that

speed at which the hydrodynamic uplift force is in equilibrium with the

load carried by the tire. At this speed the tire is being supported

completely by the layer of water. However, this is not the speed at which

spin-down is initiated. In fact, spin-down can be initiated at speeds

considerably below the critical hydroplaning speed. According to Reference 27,

in tests run on tandem wheels spin-down was initiated at speeds that were

70% the value of the predicted hydroplaning speed. In a later report (12),

Horne restates this conclusion and also states that total spin-down (wheel

stops rotating) can take place between 80% and 120% of the predicted

hydroplaning speed. These data were obtained from the tests run on aircraft tires

However, it is dangerous to use spin-down as the only criterion for

the determination of hydroplaning. As pointed out by Horne (12), as speed

is increased above the critical hydroplaning speed there is less tire-fluid

exposure time due to increased speed and a more uniform hydrodynamic pressure

exists in the contact zone. Rather than having the center of force in the

forward portion of the contact zone, it has moved toward the center of the

zone, thus shortening the moment arm and· reducing the amount of spin-down.

A similar situation exists for the water skier. As he is being pulled in

the water, the force is being exerted closer to the tips of the skis, however,

as he comes to a plane, the uplift force is positioned towards the middle

of the skis. Therefore, one should not be trapped into the fa 11 acy that H

there is·no spin-down there is no hydroplaning. Spin-down is only one

indication of the hydroplaning phenomenon. Other things such as coefficier:t

of friction and appearance or disappearance of the bow wave should also be

16

considered when determining the hydroplaning speed.

For the experimentation conducted on the hydroplaning trough, wheel

spin-down was the only criterion used to indicate loss of tire-pavement

contact. Because of this, it was decided to evaluate the pavements

studied and discuss the effects of the variables on the basis of percent

spin-down. Percent spin-down means the amount the test wheel relative

ground speed has been reduced in relation to the vehicle ground speed.

The data are presented as a plot of vehicle ground speed vs.

percent spin-down at a specific water depth showing the plots at

the various tire inflation pressures tested. ·-rhis method of presen­

tation lends itself to the development of further comparisons of data

when desired. Several examples of additional comparisons are included

in the report.

Figures 5 thru 24 are examples of these plots. These figures display

wheel spin-down characteristics for various tires, surfaces, tire pressures,

water depths, tread depths and vehicle speeds. One of the most notable

trends is the effect of tire inflation pressure. As the inflation pressure

is increased, the speed required to cause a certain amount of spin-down is

also increased. Figure 5, for example, shows that by increasing the

inflation pressure by 6 psi, the speed required to cause 10% spin-down is

increased about 4 mph. However, decreasing the tire pressure does not

necessarily decrease the speed at which a given amount of spin-down will occur.

As can be seen in Figures 5, 10 and 11, there was no significant spin-down

obtained at 18 psi for speeds up to 64 mph. It must be remembered, however,

that wheel spin-down is only an indication of hydroplaning or tire-pavement

17

"'es,

ure

'is

occur.

contact loss. One explanation for the lack of spin-down is that as the

inflation pressure is decreased, the contact area is enlarged. With this

enlarged zone, the water pressure profile across the tire is less uniform

and the spin-down torque is decreased to the point where partial hydroplaning

can occur without spin-down. Also, once the tire is completely supported by

the water layer the same water pressure profile is more uniform which can

cause a decrease or disappearance of spin-down. Figures 19 thru 23 offer

some good examples of the danger of relying solely on spin-down as an indica­

tion of hydroplaning. Figures 19, 20, 21 and 23 at 18 psi, and Figure 22 at

24 psi all show % spin-down progressively increasing with increasing speed.

However, in these particular cases, as the speeds continued to be increased,

spin-down dropped to values usually less than 5%. The phenomenon of decreasing

spin-down with increasing speed is also shown in Figures 12 and 17. This was

normally observed for an inflation pressure of 18 psi, but was also noticed

occasionally at pressures of 24 and 30 psi. It is therefore unjustified to

assume that if a tire has not spun-down it has not lost some pavement contact

in the lower range of inflation pressures. In such cases, it may be helpful

to perform skid tests at varying speeds to determine at what speed the coef­

ficient of friction reaches minimum value.

Figures 5 thru 24 exhibit another interesting point. It should be

noticed that each family of curves for a certain tire and water depth are

approximately parallel. This was true in all instances. In fact, the

curves for the same tire, even as the water depth was varied, showed a

similar slope. This would indicate that each tire has its own "hydroplani 1g

characteristics". For example, the steeper the curves the less sensitive

the tire is to increases in speed. The closer grouped the curves the less

18

sensitive the tire is to inflation pressure changes.

Figures 25 and 39 are plots of tire inflation pressure vs. ground

speeds at 10%, 32% and 60% spin-down. These plots are compared to the

equation for critical hydroplaning velocity presented by Horne in refer­

ence 27 (i.e. VCR= 10.35 ;r-) where P =tire inflation pressure in psi.

Figures 25, 27, 28, 31 thru 36 and 39 show comparisons of tires with full

tread depths with Horne's equation. In all cases, the experimental plots

are approximately parallel with each other, but not necessarily parallel

with plots of other tires. This again indicates the possibility that the

tires may possess individual characteristics which may affect the speeds

at which they hydroplane. These full tread depth tires require compara­

tively high speeds to cause spin-down. Therefore, simply because a plot

is to the right of the NASA equation does not mean that the tire is defi­

nitely hydroplaning. It simply means that the speed required to cause a

certain amount of spin-down is higher due to the tires' construction and

that there has been at least a partial loss of pavement contact.

Figures 26, 29, 37 and 38 compare the results obtained for a smooth

or worn tire with Horne's equation. For these plots, even when total spin­

down was compared to the equation, the speeds were far below those perdicted.

It should be noticed that the slopes differ from that of the NASA equa-

tion. Also, it has been observed that the slopes are affected by the

test surfaces. However, the slopes of these plots do not seem to be

affected by the water depths at which the tests were run. The water depth

did affect the positioning of these plots, that is, it affected the speed

at which a certain amount of spin-down would take place. But, as stated by

Horne (27), the speeds for even 10% spin-down are within 70% of the speeds

19

predicted by the equation.

As can be seen from the above observations it would be extremely

difficult to derive an equation for hydroplaning velocity that would fit

all tires under varying conditions. Horne has done an exceptional job,

even though as he admits, his equation is very 1 imi ted. But the agreement

of the data presented with his equation is quite encouraging.

Figures 40 thru 48 are plots of water depth vs. ground speed at which

10% spin-down occurred and are used to make various comparisons.

Figures 40 and 41 show the effect of varying the wheel load from 800 lbs.

to 1085 lbs. The results for the smooth tire are plotted on Figure 40 and

indicate that increases in the wheel load increases the speed necessary to

cause 10% spin-down. However, the results for a tire with a full tread

depth, plotted in Figure 41, indicate the reverse takes place. These data

indicate that the hydroplaning speed is less dependent on wheel load than

other variables. However, it should be made clear that only a limited amount

of data were collected and this may not be true for other tire-tread depth­

texture-wheel load combinations.

Figure 42 shows a comparison of tire No. 4, the F70-14 wide tire, with

Tire No.7, a 7.75-14 bias ply. The bias ply tire required higher speeds

to cause the same amount of spin-down obtained with the wide tire. These

results are in agreement with the findings of other researchers which indi­

cate that the hydroplaning speed decreases as the tire width increases. In

other words, the wider the tire, the lower the speed to cause a given amourt

of spin-down, all other things being equal. When a person water skis, it ~s

much easier to hydroplane using an aquaplane rather than two skis or using

two skis instead of a single ski. The more surface area available, or the

larger the contact area, the easier it is to hydroplane. This same trend

20

was observed on all pavements tested.

Figure 43 clearly demonstrates the effect of tire tread depth on spin­

down. The data shown are for bias ply tires similar in all aspects except

tread depth. As can be seen, the speeds to cause spin-down for the worn

tires are considerably lower than for the fully treaded tire. In some cases

the difference was as great as 11 mph. Since the tire tread grooves act as

a channel for partial escape of the water trapped beneath the tire, this is

a very important variable. When the tread is worn smooth, there is no drain­

age but through the channels in the pavement surface texture .. A limit is

reached beyond which even deep pavement textures cannot prevent hydroplaning

at higher speeds. The maintenance of good tread depth extends this limit

significantly.

A bias ply glass belted F78-14 smooth and a steel belted radial 195-14

full tread were tested only on the concrete surface (No. 1), the jennite

surface (No. 4) and the grooved concrete surface (No. 5). The glass belted

tire produced data similar to the other smooth tires tested. The radial tire

produced usable data within the capability of the tow vehicle only on the

jennite surface. This would tend to indicate that the radial tire is less

susceptible to spin-down and therefore less susceptible to hydroplaning,

but a definitive statement cannot be made until methods of measurement other

than spin-down are available.

Figures 49 and 50 show that the data collected in previous years work

could be repeated. Between 1972 and 1973, it was necessary to replace the

jennit~ surface (No. 4) but no significant texture change was measured.

Bias ply full tread and smooth tires were rerun in the repeatability checks

and the results are shown in Figure 49. In preparation for grooving the

21

)-

t

· ses

as

is

rain-

ing

14

:ed

tire

s

I ,her

, ks I

I

trough, surfaces 2, 3 and 4 were then removed using a hydro-laser. Bias

ply tires full tread and smooth were run again on the original burlap drag

concrete (No. 1). Results are shown in Figure 50.

A comparison of the pavements tested is shown in Figures 51 thru 56.

As stated previously, the textures for the five pavements tested were 0.018

in., 0.146 in., 0.033 in., 0.020 in. and 0.047 in., respectively as measured

by the silicone putty method. As can be seen from Figure 51, the speeds to

cause spin-down on the seal coat surface (No. 2) are much higher than for the

concrete surface (No. 1). In fact, very scant data were obtained at depths

below 0.70 in. for all tires tested on the seal coat surface. The speeds at

which spin-down occurred on the concrete pavements are well below those

traveled on high speed roadways. The data presented are those obtained

from a bias ply tire with a full tread depth. Figure 52 is a similar com­

parison using the data obtained from the F70-14 wide tire with a full tread

depth. Again, the speeds to cause spin-down on the seal coat surface were

higher. The speed to cause spin-down at 0.70 in. water depth on the seal

coat surface was higher than the speed to cause 10% spin-down at 0.40 in.

on the concrete surface.

Figure 53 is a comparison of surface 1 (concrete) with surface 3 (hot

mix asphalt). Even though the hot mix pavement was shown to have a higher

texture than the concrete (0.033 in. as opposed to 0.018 in.), the speeds

necessary to cause spin-down are lower on the hot mix pavement. The reason

for this could be the fact that the hot mix pavement was rolled with a fla:

wheel steel roller. Because all of the texture depth is not inter-connect=d,

it provides fewer escape paths for the water trapped beneath the tire. This

situation may be compared to that of a waffle iron and the waffle. On the

22

face of the iron, the depressions are interconnected while in the waffle

the impressions are not. Both the face of the iron and the waffle would

have about the same average texture depth if measured by methods used to

acquire texture depths in this study.

By comparing surfaces 3 and 4 shown in Figure 54, it can be seen that

the speeds to cause spin-down are higher for the hot mix surface. This

result is to be expected. The jennite surface is relatively smooth with

very little texture and offers poor drainage for trapped water. This sur­

face could be considered similar to a bleeding asphalt pavement. It was

observed, however, that the speeds to cause spin-down on the jennite sur­

face were higher than expected in some cases. It is possible that the

test tire was actually hydroplaning, thus making the pressure profile more

uniform and decreasing the amount of spin-down observed. Further testing

would have to be performed in order to determine the cause.

In deriving his equation, Horne neglected the effect of water depth

on hydroplaning speed. In this way he implied that as long as the asperi­

ties are covered, hydroplaning will occur at a certain speed depending on

the tire pressure. From the data collected here, it seems that the effect

of water depth is more pronounced for some surfaces and tires than for

others. Figure 46 shows that increasing the water depth on surface 4 (jenni

has little effect on the speed at which spin-down occurs. Increasing the

water depth on surface 3 (hot mix asphalt) has the effect of decreasing

the speed at 10% spin-down as much as 9 mph: (Figure 45). When comparing

surfaces 1 and 3 (Figure 53) it can be seen that the water depth has about

the same effect on both surfaces when :the higher inflation pressures are

concerned. But as the inflation pressures are decreased, the apparent

23

effect of the water depth is decreased. However, there is no real consis­

tency in this change.

In Figure 55, the two belted tires are compared on the three surfaces

upon which they were tested. The difference in 10% spin-down at 24 psi was

13 mph for the grooved concrete surface but some of this difference is

attributable to smooth vs. full tread depth.

Figure 56 effectively compares all five surfaces for one tire, the

F70-14 wide tire full tread. The seal coat surface (No. 2) is superior to

the other surfaces with the grooved concrete (No. 5), second highest texture,

the next best. These data in conjunction with the information already dis­

cussed and presented in Figures 51 and 52 emphasize the importance of

drainage efficiency at the tire pavement interface.

Figure 57 shows a comparison of the bias ply tires tested on surface 4.

The speeds shown in these figures are for 10% spin-down, and are plotted

against water depth. As can be seen, there is little agreement among the

tires as water depth and tire pressure are varied. From the data presented,

it appears that tire No. 7 yielded the best results in terms of speed at a

given amount of spin-down. From these results it can be seen that even

similar tires possess individual spin-down or hydroplaning characteristics.

Since the configuration and composition of the tires are basically the same,

the difference may be caused by the tread design. Unlike tire 5, both tires

1 and 7 have a basic 4 groove tread design. Tire 1 has a small, straight

groove around the center of the tread pattern and a pattern of unconnected

saw tooth cuts in the tread. This fact seems to be the difference. Tire

7 also has a 4 groove tread pattern but has a more extensive pattern of

cuts which are deeper, wider and inter-connected. Not only do they form

24

a continuous pattern, but they are connected to the main groove design

allowing exit of water from the rib area which has the effect of easing

the pressure build up beneath the tire. Tire 5, is a 6 groove tread

design with no cuts in the ribs and only limited siping.

Figure 58 compares the two belted tires tested. These is a large

variation between the data presented; however, the portion of this varia­

tion attributable to the difference in tread depth is not known. Tire

No. 9 was a smooth glass belted bias ply and tire No. 10 full tread steel

belted radial. The tread design on tire No. 10 has a basic 4 groove pat­

tern without interconnections between the grooves.

Figures 59, 60 and 61 summarize data plotted on other figures in

this report. In general, the degree of influence of the variables tested

on the speed to cause spin-down, from most to least, is as follows: tread

depth, tire inflation pressure, texture and water depth. It must be re­

membered that this is simply a general trend depending on the tire tested.

From the electronic instrumentation data, it was observed that if

wheel spin-down occurred it began as soon as the tire came in contact with

the water in the hydroplaning trough. In order for the spin-down to reach

its maximum value, it is necessary for the spin-down moment to overcome

inertia of the rolling tire. Time is required to accomplish this. This

time is indicated as distance on the read out equipment. For example,

considering the seal coat surface and using tire No. 4 with an inflation

pressure of 24 psi and a water depth of 0.7 in. (see Figure 10), it took

approximately 80 ft. to reach a spin-down of 20% when entering the trough

at 48 mph. However, when entry speed was .increased to 58 mph it took

240 ft. of travel before a spin-down of 78% was attained; after 80 ft.

25

. 1

1g

tee 1

Ja t-

>ted

·ead

:ted.

i

with i

'each

ie the

is

,on I

Jok

I ugh

the

tachometer generator traces indicated a wheel spin-down of approximately

20%. The important point here is that the tire is influenced immediately

when it comes in contact with the water.

Therefore, it can be concluded that partial loss of pavement contact

or partial loss of traction occurs soon after the tire comes in contact

with a flooded pavement. If the flooded portion of pavement is not long

and the vehicle is not subjected to abnormal maneuvers, the tractive force

may be regained before a hazardous condition develops. For a given vehicu­

lar ground speed that is high enough to cause wheel spin-down, it can

said that the probability of a hazardous vehicle control condition developing

increases with increasing length of the flooded pavement.

26

VI. APPLICABILITY TO

SAFE WET WEATHER SPEEDS

In legislative action, Section 167 of Senate Bill No. 183, 62nd

Legislature, the State of Texas has given authority to the Highway Commission

to set wet weather speed limits at specific places on Texas highways.

Although by no means encompassing all the factors which could be con-

sidered in· determining safe speeds, the current data on hydroplaning

give indications of the speeds which result in a potentially marginal

condition with regard to vehicle control. Hydroplaning is only one of

the many factors which must be considered in determining safe speeds.

It is limited to the case when a significant depth of water is encountered

on the roadway due to an exceptionally high intensity rain or to poor

drainage, puddles, wheel ruts, low cross slopes, etc.

In the discussion presented in this section, it is assumed that a

10% spin-down of a free rolling automobile wheel signifies the approach

of a control problem due to either loss of stopping capability or loss

in directional control. In this section the 10% spin-down speed will

be called the "critical speed''.

Figures 62 thru 65 show approximate curves which represent the

data developed. The effects of pavement texture, tire pressure and tire

type or condition are shown by these curves. Several tires are used

to illustrate the various effects.

Bias ply tires 7 and 8 represent full tread depth and smooth tires

respectively. Tire No. 4 is full tread depth with a wide tire configuraticn.

Wheel load in all cases is 1085 lbs.

27

The influence of pavement texture on critical hydroplaning speed (as

indicated by 10% spin-down) is significant as shown in Figure 62. An in­

crease in critical speed of 13 mph, from 47 to 60 mph, is indicated at a

water depth of 1/4 inch when the macrotexture is increased from 0.018 in.

to 0.145 in. This difference apparently decreases slightly as water depth

increases. Pavement texture effects are also illustrated in Figure 63 for

tire No. 4, the wide tire.

The effect of tire pressure is illustrated by Figure 64. The tire

pressures of 24 psi to 36 psi shown in this figure account for approxi­

mately ·70% of the range of tire pressures observed in a study of 501 wet

pavement accidents in Texas (25).

Figure 64 shows that at a water depth of 0.1 inch, the critical speed

increases by approximately 10 mph (from 48 to 58 mph) as tire pressure in­

creases from 24 to 36 psi. This difference becomes much smaller at greater

water depths.

The effect of three different tires on critical speed is shown is

Figure 65. Unlike the effects of texture and pressure, the differences

between these tires increase as the water layer becomes thicker. At a

water depth of l/2 inch the critical speed varies from 43 to 51 mph. It

is notable that the full tread depth wide tire falls between the bias

ply smooth and bias ply full tread depth as related to critical speed.

Figure 66 is a consolidation of individual wheel tire pressure graphs

as reported in reference (25). The 50 percentile pressure of 27 psi is

used in Figures 29, 63 and 65.

From graphs presented in this report, it is obvious that there is

no one critical speed that is appropriate for the range of pavements,

tire pressures, water depths and tire parameters investigated.

28

er

Partial hydroplaning, and thus some loss of vehicle control, may result

at speeds significantly below the posted speed limit on major rural highways

in Texas. No critical speeds below 39 mph were found and a speed of 50 mph

seems to be the approximated median value for all parameters investigated.

It is therefore suggested that a reduction of speed to 50 mph be con­

sidered on any section of highway where water can accumulate to depths of

0.1 inch or more during wet periods. Further improvements in the safety

of these sections can be made if a high macrotexture surface is placed and

maintained.

It has been conclusively shown by numerous tests that the hydroplaning

phenomenon can occur for many tires and recommended tire pressures at

speeds lower than current speed limits. It is possible, however to design

highways so that hydroplaning will be an extremely rare occurrence. Ivey

(53) has shown that high intensity rainfall is a rare occurrence in Texas,

with a probability of experiencing over one inch per hour less than 0.05%

of the time. The highway engineer has the prerogative, based on this

study to choose an appropriate design rainfall. If this is done, the

following is an example of what design criteria can be applied to make

hydroplaning a remote possibility.

Example: Assume that the design rainfall has been chosen

as l in./hr. (This then means that less rainfall occurs 99.95%

of the time.) Based on the fact that hydroplaning cannot

occur at zero water depth, defined as that depth coincident

with the tops of the pavement surface asperities, choose

appropriate combinations of cross slopes and textures for

various drainage path lengths which will give a zero water

29

depth at a rainfall intensity of 1 inch per hour. This

has been done using the equation developed by Gallaway

which was presented in nomograph form in Report 135-2F (54).

This equation is:

L0.43 d = 3. 38 X 10 3 - T

Where

d = Water depth in inches

T = Texture depth in inches

L = Drainage path length in feet

I = Rainfall intensity in in./hr.

s = Cross slope in in./ft.

Figure 67 shows the results of these computations for drainage

path lengths of 12 and 24 ft. If the cross slope is chosen as

3/16 of an inch per ft., it is required that 0.040 and 0.055

inches of texture be maintained for 12 and 24 ft. respectively

if water depths are to be controlled to the asperity top level.

Note that combinations of cross slope and texture that fall to

the right of each curve would result in lower (negative) water

depths and those combinations which fall to the left result in

positive (unsafe) water depths.

Since all automobile tires, as presently designed; appear to 8e sus­

ceptible to hydroplaning at some combination of surface, water depth and

speed, the vehicle operator must be aware of visual indications of poten­

tial hydroplaning conditions. Surface water on a highway can be detected

30

~ !

by a driver and speed reduced appropriately. Some of the visual indica­

tions of dangerous water accumulations are as follows:

A. Puddling in low spots and wheel ruts appear as very

shiney areas on the road surface.

B. The coarser the texture of the pavement, the less light

reflected from the surface.

C. Traffic will indicate to the driver the water quantity

on the road by the amount of spray produced by tires.

D. Traffic tire tracks tend to wipe the surface. The

length of time these wiped tracks are visible, par­

ticularly in areas where drainage is crossing the

road, is an indication of the amount of water present.

31

VII. CONCLUSIONS

The following general conclusions are based upon the data obtained

from the tests performed at the Texas Transportation Institute's Research

Annex and the assumption that 10% spin-down causes a sufficient reduction

in the frictional coefficient so that vehicle stability is affected.

1. Wheel spin-down is normally initiated at a ground speed

that falls within 70% of the critical hydroplaning

speed predicted by Horne's NASA equation. Total spin­

down (wheel stops rotating) may occur at speeds lower

than those predicted by Horne.

2. As the tire tread becomes worn, the drainage provided by

the tread becomes less efficient and the speed to cause

a given amount of spin-down is decreased. Speeds to

cause spin-down on worn tires are considerably less than

for tires with a full tread depth.

3. Decreasing the tire inflation pressure has the effect of

increasing the area of the contact zone. In the majority

of cases, the larger the area of the contact zone, the

lower the speed to cause spin-down.

4. Increasing the tire width has the effect of decreasing

the critical speed.

5. An increase in water depth generally has the effect of

decreasing the speed at which wheel spin-down is

initiated.

6. An increase in the macrotexture of the pavement increases

the speed at which spin-down occurs. The interconnection

32

I

of drainage channels in the pavement surface is an

important factor in minimizing hydroplaning.

7. Even though a tire may not have reached the total

hydroplaning speed, a hazardous condition may exist

when the wheel has partially spun down and some tire­

roadway surface friction has been lost.

8. Many factors must be considered in determining safe

wet weather speeds. From a hydroplaning standpoint,

it is suggested that a reduction of speed to 50 mph

be considered on any section of highway where water

can accumulate to depths of 0.1 inch.

33

REFERENCES

1. Allbert, B. J., "Tire and Hydroplaning," Society of Automotive Engineers, Automotive Engineering Congress, Detroit, Michigan, January 8-12, 1968.

2. All bert, B. J., Walker, J. C., and Maycock, G., "Tyre to Wet Road Friction," Proceedings of the Institution of Mechanical Engineers, Volume 180, Part 2A, No. 4, 1966.

3. Ashkar, B. H., "Development of a Texture Profile Recorder," Texas Highway Department, Report No. 133-2, 15 pp., July 1970.

4. Barrett, R. V., "Drag and Spray Measurements from a Small Phenumatic Tyre Travelling through a Water Layer," Technical Information and Library Services, Ministry of Aviation, December 1963.

5. Beaton, J. L., Zube, E., and Skog, J., "Reduction of Accidents by Pavement Grooving," Highway Research Board Special Reports, No. 101, pp. 110-125,5 fig., 4 tab., 6 ref., 1 app., 1969.

6. Bevilacqua, E. M., and Percarpio, E. P., "Fundamental Aspects of Lubricated Friction of Rubber- VII: Notes on a Standard Tire and Procedure for Skid Testing," Presented at a meeting of the Division of Rubber Chemistry, April 23-26, 1968.

7. Bevilacqua, E. M., and Percarpio, E. P., ''Lubricated Friction of Rubber," Reprinted from Rubber Chemistry and Technology, Vol. 41, No. 4, September 1968.

8. Colley, B. E., Christensen, II. P., and Nowlen, W. J., "Factors Affecting Skid Resistance and Safety of Concrete Pavements," Hi gh11ay Research Board Speci a 1 Reports, No. 101 , pp. 80-99, 19 fig. , 4 tab., 38 ref. , 1969.

9. Daughaday, H., and Balmer, G. G., "A Theoretical Analysis of Hydroplaning Phenomena," Prepared for Presentation before Committee D-B4 - Surface Properties - Vehicle Interaction, Highway Research Board, Washington, D. C., January 14, 1970.

10. Davisson, J. A., "Basic Test Methods for Evaluating Tire Traction," Society of Automotive Engineers, Automotive Engineering Congress, Detroit, Michigan, January 8-12, 1968.

11. DeVinney, Halter E., "Factors Affecting Tire Traction," Society of Automotive Engineers, Mid-Year Meeting, Chicago, Illinois, May 15-19, 1967.

34

I

12. Dreher, Robert C., and Horne, Halter B., "Ground-Run Tests with a Bogie Landing Gear in Water and Slush,'' NASA Technical Note D-3515, National Aeronautics and Space Administration, Washington, D, C., July 1966.

13. Dugoff, Howard, and Ehrlich, I. Robert, "Laboratory-Scale Model Experiments to Investigate Aircraft Tire Hydroplaning," Reprinted from Proceedings, of the Seventh Annual National Conference on Environmental Effects on Aircraft and Propulsion Systems.

14. Dugoff, H., and Fancher, P. S., ''An Analysis of Tire Traction Properties and Their Influence on Vehicle Dynamic Performance," International Auto Safety Conference Compendium, pp. 341-366, 1970.

15. Ehrlich, I. R., Shaefer, A. R., and Wray, G. A., "Parameters Affecting Model-Tire Hydroplaning and Rolling Restoration," Davidson Laboratory Report SIT-DL-70-1408, March 1970, Stevens Institute of Technology, Castle Point Station, Hoboken, N.J.

16. Eshel , A. , "A Study of Tires on A Wet Runway," Fi na 1 Report Pre­pared under Contract No. NASW-1408, National Aeronautics and Space Administration, Ampex Corporation, Research and Engineering Publication, September 1967.

17. French, T., "Developments in Tyres Relating to Vehicle Safety and Accident Prevention," Dunlop Rubber Co., Ltd., Fort Dunlop, Erdington, Birmingham.24, England, August 1964.

18. French, T., and Hofferberth, Dr. W., "Tyre Development and Appli­cation," the Dunlop Company Limited, Presentation to the Inter­national Rubber Conference, Brighton, England, May 15-18, 1967.

19. Gengenbach, Herner, "The Effect of Wet Pavement on the Performance of Automobile Tires," Cornell Aeronautical Laboratory, Inc., Buffalo, New York, July 1967.

20. Gingell, V. R., "Grooving the Runway at Washington National Airport," Civil Engineering, ASCE, Vol. 39, No. 1, pp. 31-33, 1 fig., 3 phot., January 1969.

21 ·Goodwin, ~~. A., "Pre-Evaluation of Pavement f~aterials for Skid-Resistance A Review of U. S. Techniques," Highway Research Board Special Reports, No. 101, pp. 69-79, 10 fig., 15 ref., 1969.

22. Gough, V. E., and Badger, D. W., "Tyres and Road Safety," Pre­sented at the Fifth World Meeting of the International Road Federation, London, September 18-24, 1966. ·

23. Gray, W. E., "Measurements of 'Aquaplaning Height' on a f1eteor Aircraft, and Photos of Flow Pattern under a t1ode 1 Tyre," Aeronautical Research Council Current Papers, Ministry of Aviation, London, 1964.

35

24. Grosch, K. A., and Maycock, G., "Influence of Test Conditions on The Wet Skid Resistance of Tyre Tread Compounds," Rubber Industry, Inst. Trans., Vol. 42, No.6, pp. 380-406,9 fig., 10 tab., 6 phot., 19 ref., December 1966.

25. Hankins, Kenneth D., Morgan, Richard B., Bashar, Ashkar and Tutt, Paul R., "The Degree of Influence of Certain Factors Pertaining to the Vehicle and the Pavement on Traffic Accidents Under Wet Conditions," Texas Highway Department, Departmental Research, Report No. l33-3F, September 1970.

26. Holmes, K. E. and Stone, R. D., "Tire Forces as Functions of Cornering and Braking Slip on Wet Road Surfaces," Ministry of Transport, London, RRL Rept. LR 254, 42 pp., 1969.

27. Horne, Walter B., and Dreher, Robert C., "Phenomena of Pneumatic Tire Hydroplaning," NASA Technical Note D-2056, National Aeronau­tics and Space Administration, Washington, D. C., November 1963.

28. Horne, Walter B., "Interactions Between a Pneumatic Tire and a Pavement Surface," presented at the Bureau of Public Roads Program Review Meeting, Gaithersburg, Maryland, December 6-8, 1966.

29. Horne, Walter B., and Joyner, Upshur T., "Pneumatic Tire Hydro­planing and Some Effects on Vehicle Performance," Society of Automotive Engineers, International Automotive Engineering Congress.

30. Horne, Walter B., and Leland, Trafford J. W., "Influence of Tire Tread Pattern and Runway Surface Condition on Braking Friction and Rolling Resistance of a Modern Aircraft Tire," NASA Technical Note D-1376, National Aeronautics and Space Administration, Washington, D. C., September 1962.

31. Horne, Walter B., "Skidding Accidents on Runways,and Highways Can Be Reduced," reprinted fr.om Astronautics & Aeronautics, August 1967.

32. Horne, Walter B., "Tire Hydroplaning and Its Effects on Tire Traction," presented at the Forty-Sixth Annual Meeting of the Highway Research Board, Washington, D. C., January 16-20, 1967.

33. Kessinger, B. G., and Neilson, W. D., ''Skid Resistance Study (Type B), "Arkansas State Highway Department, Federal Highway Administration, HRC-27.

34. Leland, T. J. W., Yager, Thomas J., and Upshur, T. Joyner, "Effects of Pavement Texture on Wet-Runway Braking Performance," NASA Technical Note D-4323, Washington, D. C., January 1968.

36

35. Martin, C. S., "Hydrodynamics of Tire Hydroplaning," Final Report, Project B-608, prepared for National Aeronautics and Space Admini­stration by the School of Civil Engineering, Georgia Institute of Technology, Atlanta, Georgia, June 15, 1966.

36. Martin, F. R., and Judge, R. F. A., "Airfield Pavements: Problems of Skidding and Aquaplaning,'' reprinted from Civil Engineering, 8 Buckingham Street, London, W. C. 2, December 1966.

37. Meyer, W. E., "Pavement Friction and Temperature Effects, "Highway Research Board Special Reports, No. 101, pp. 47-55, 15 fig., ll ref., 1969.

38. Moore, D. F., ''The Logical Design of Optimum Skid-Resistant Surfaces," Highway Research Board Special Reports, No. 101, pp. 39-45, 7 fig., 11 ref., 1969.

39. Moore, D. F., "Drainage Criteria for Runway Surface Roughness," Journal of the Royal Aeronautical Society, May 1965, pp. 337-342.

40. Moore, D. F., "A Review of Squeeze Films," Wear, Vol. 8, No. 4, July/August 1965, pp. 245-263.

41. "Reducing Hazards on Slippery Runways," Engineering, UK, Vol. 204, No. 5303, p. 912, December 8, 1967.

42. Saal, R. N. J., "Laboratory Investigation into the Slipperiness of Roads," Chemistry and Industry, Jan. 3, 1936.

43. Sabey, B. E., and tlilliams, T., "Factors Affecting the Friction of Tires on viet Roads," International Auto Safety Conference Compendium, pp. 324-340, 1970.

44. Segel, Leonard, Ludema, K. C., and Dugoff, H. J., ''New Areas for Tire Performance Methods," American Society for Testing and Materials, Philadelphia, Pa., June 1968.

45. Staughton, G. C., and Williams, T., "Tyre Performance in Wet S.urface Conditions," Road Research Laboratory Report LR 355, 1970, Road Research Laboratory, Crowthorne, Berkshire.

46. Stocker, A. J., and Gregory, R. T., "Construction of a ·Facility to Study Variables Associated with Hydroplaning," Texas Transpor­tation Institute Progress Report No. 1, Study No. 2-8-70-147, HPR-1(9), Texas A&M University, College Station, Texas, March 1971.

47. Tarpinian, H. D., "Equipment for Measuring Forces and ~1oments on Passenger Tires," Society of Automotive Engineers, International Automotive Engineering Congress, Detroit, Michigan, January 13-17, 1969.

37

48. "The Influence of the Road Surface on Skidding," Symposium, October 16, 1968, Salford Royal Advanced Tech. Coll., October 1968.

49. Tsakonas, S., Henry, C. J., and Jacobs, W. R., "Hydrodynamics of Aircraft Tire Hydroplaning," prepared under Contract No. NSR31-003-016 for National Aeronautics and Space Administration, NASA Contract Report CR-1125, ~lashington, D. C., August 1968.

50. Wray, G. A., and Jurkat, M. P., "Derivation of an Empirical Equation Relating Critical Hydroplaning Speed, Water Film Thickness and Nominal Contact Patch Bearing Pressure for an 8" Diameter Polyurethane Mode 1 Tire," Davidson Laboratory Report SIT -DL-70- 1479, March 1970, Stevens Institute of Technology, Castle Point Station, Hoboken, New Jersey.

51. Yager, Thomas J., "Hydroplaning -A Factor in Skidding," Presented at the Twelfth Annual Alabama Highway Engineering Conference, Auburn, Alabama, April 1-2, 1969.

52. Zube, E., Skog, J. B., and Kemp, G. R., "Field and Laboratory Studies on Skid Resistance of Pavement Surfaces," California Division of Highways, Bureau of Public Roads, HPR-1(5), B-3-1.

53. Ivey, D. L. and Lehtipuu, E. K.,"Rainfall and Visibility, The View from Behind the Wheel;'' Res. Rept. No. 135-3, Texas Transportation Institute, August 1974.

54. Ivey, D. L., Hankins, K. D. and Weaver, G. D., "Factors Vehi c 1 e Skids: A Basis for Wet Weather Speed Zoning," 135-2F, Texas Transportation Institute, February 1973.

38

Affecting Res. Rept.

/

64

62

60

58

~

.<: ~ 56 '-'

""' <U 54 <U p.

"' ""' (j

52 w " \0 0 ,..

"' 50

48

46

44

42

Tire No. 4 F70-14 Hide Tire (full Tread Def'th) \<later Depth - 0.25 in. h'heel Load - 1085 lbs

00.

-------0~.

........... 0~

11::,.

~ 11::,.

5 10 15 20

El_El...........-EJ

El----

"0.

11::,.

25 30 35 40 45

Spin-Down (%)

50 55 60

Inflation Pressure

0 36 psi

El 30 psi

11::,. 24 psi

18 psi No Spin-Dmm

65 70 75 80

FIGURE 5. EFFECT OF VEHICLE GR6UND SPEED ON \.JHEEL SPIN:_DO\JN FOR CONCRETE PAVEMENT.

6fj

58

56

~ 54

E ~

52 "0 0) 0)

0.

"' 50 "0

"' _,. " 48

0 0 ... v

46

44

42

Tire No. 4 F70-14 Wide Ti~e (Full Tread Denth) Water Depth - 0.40 in. Hheel Load - 1085 lbs

0

0 ---- 0...-

8 _......----.....-------

0 ----------8

.....----15 _............-8

_............- A 8 8~-8

........... ~ ...........-- iS.

~-·-~ 5 10 15 20 25 30 35

8

.....----- 8 _......

8

40 45

Spin-Do~o~n (%)

__...........-0 0

50 55 60

_......------

Inflation Pressure 0 36 psi

8 30 psi

8 24 psi

-•- 18 psi

65 70 75 80

FIGURE 6. EFFECT OF VEHICLE GROUND SPEED ON W!EEL SPJN-DOh'N FOR CONCRETE PAVEMENT.

85

51

50

49

48

47 ~ I .c "" s 46 ~

"tl Q)

..,.Q) 45 ~o.

Cll

"tl 0:

44 " 0

" " 43

42

41

40

EFFECT OF VEHICLE GROUND SPEED ON !VHEEL SPIN-DOh'N FOR CONCRETE PAVEMENT.

Tire No. 8 7.75-14 Bias Ply (Smooth) Water Depth - 0.40 in. Wheel Load - 1085 lbs

0

----------- ---- [!]

~

IX

8 Inflation Pressure

0 36 psi

El 30 psi

&. 24 psi

10 lS ZO 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95

Spin-Down (%)

FIGURE 7. EFFECT OF VEHICLE GROUND SPEED ON HHEEL SPIN-DOI-lN FOR CONCRETE PAVEMENT.

.p. N

50

49

48 I

I 47

~

..c 0.

-.5 46 ~ ., "' "' ~ 45 ., "' " ~ 44

Tire No. 8 7.75-14 Bias Ply (Smooth) Hater Depth- 0.70 in. Hheel Load - 1085 lbs.

0 ~

0

0

"[_@ ____ @

42 . -----& I

41

40 I

~

0

0

0

Inflation Pressure

0 36 psi

0 30 psi & 24 psi

~~~~~~~~~~~~~~~~~~~~

15 20 25 30 35 40 45 so 55 60 65 70 75 80 85 90 95 100

64

62

...... 60 .0:

"' s ~

58

"" "' "' "' "' 56 ..,.

"" w <l

" 0 54 ... ""

52

so

Tire No. 4 F?0-14 \vide Tire (Full Tread Depth) Water Depth - 0.40 in. Hheel Load - 1085 lbs

-·- 0

0/ /-·-

8 ?' /

5 10 15 20

/

G~G

8/

25 30 35 40

Spin-Down (%)

75····· 86 85 90

G~ 8

Inflation Pressure

0 36 psi

G 30 psi

8 24 psi

-·- 18 psi

45 50 55 60 65 70 75 80

FIGURE 9. EFFECT OF VEIIICLE GROUND SPEED ON HHEEL SPIN-DOI.nl FOR SEAL COAT SURFACE TREATMENT.

95 100

85

64

62

60

~ 58 .c 0. E ~

""' 56 "' "' 0.

""' "' ""' 54 ""' " " 0 ... l!> 52

5J

48

Tire No. 4 F70-14 Hide Tire (Full Tread Dent h) Hater Depth- 0.70 in. \Vhee1 Load - 1085 lbs

0

~ ~0

0

8

0

_.,...If:{

5 10 15 20 25 30 35 40 45 50

Spin-Dmm (%)

~ ~ 0 8

8

8

Inflation Pressure

0 36 psi 0 30 psi

8 24 psi

18 psi No Spin-Down

55 60 65 70 75 80 85

FIGURE 10. EFFECT OF VEHICLE GROUND SPEED ON \<'HEEL SPIN-DOHN FOR SEAL COAT SURFACE TREATMENT.

~

.c: "" s ~

"" -1=> QJ

01 QJ

"" Cl)

"" <= ::> 0 ... "

Tire No. 8 7.75-14 Bias Ply (Smooth) \,Tater Depth - 0.40 in.

64 r lfuee1 Load - 1085 1bs

62

60 ~ 0 ~/ 58 1- 0

56

54

52 I & /&

50

48

46 .

44

5 10 15 20 25 30 35 40

Spin-Down (%)

ru1t "'"'".u-c:uAT SDRf'ACE. TREATMENT.

Inflation Pressure

0 36 psi

[!] 30 psi

8. 24 psi 18 psi No Spin-Down

45 50 55 60

FIGURE 11. EFFECT OF VEHICLE GROUND SPEED ON I !HEEL SPIN-DO\JN FOR SEAL COAT SURFACE TREATHENT,

62

60

58

56

~

.c 54 g-~

"' 52 (lJ (lJ ..,."'

"'"' ] 50 " 0 .... '-' 48

46

44

42

Ti. re :·'o. 8 7. 7 5-14 Bias Ply (Smooth) Hater Depth - 0. 70 in. 1.n1eel Load - 1085 1bs

---::::---0 0 t!J

-------

[!)

-·-

&---[!)

_& __________________ & & ~ -·-

-·--·---

5 10 15 20 25 30 35 40 45 50 55 60 65 70

Spin-Down (%)

Inflation Pressures 0 36 psi

El 30 psi

b 24 psi

-·- 18 psi

75 80 85

SPIN-DOWN FOR SEAL COAT SURFACE TREATMENT.

90

'

95

5

56

54

....... 52 .c:

"" a ~

., 50 Ql Ql

"" "' 48 """ ..... .,

c " 0 46 ,...

C>

44

42

40

38

pin-Down (%)

}lGURl' 12. EFFECT OF VEHICLE GROUND

Tire,No. 4 F70-14 Wide Tire (Full Tread Depth) Water Depth - u.4U in. Wheel Load - 1085 lbs.

~ G

0 ~ ~ I!]

~~ -----0 ~0-----

I!]

..,....,... l!l~ b:.~

............

~

10 20 30 40 50

% Spin-Down

I!] 8.

~ b:.

~

60

~

Inflation Pressure 0 · 36 psi 8 30 psi 8. 24 psi

-·-18 psi

70 80 90

FIGURE 13. EFFECT OF VEHICLE GROUND SPEED ON WHEEL SPIN-DOWN FOR HOT 11IX PAVEMENT.

100

~

.c 0. s ~ .,

QJ QJ 0. _.,. "' (X) ., " •::> 0 ....

. t.!)

Tire l!o. 7 7 •. 75-14 Bias Ply (Full Tread Depth) 64 .L Water Depth - 0.40 in.

Wheel Load - 1085 1bs.

62

60

58

561 0

54 -0---- --------- 0

52

50 EJ

48t- 8 -----46 8

44 .l Ill --I 42

10 20 30 40 50

% Spin-Down

60

0--------

---- 8 00

70

---- 8-----11:.

Inflation Pressure

0 36 psi 0 30 Psi 8. 24 psi

-·-18 psi

80 90 100

FIGURE 14. EFFECT OF VEHICLE GROUND SPEED ON \oJHEEL SPIN-DOHN FORI-lOT MIX PAVEMENT.

v-..-.---,..,-.-.-=c-.::.--- --.·,r--;.!;T'o---u-owH--l. .. Ol'\. t'llfl"--- '1'1LX. ______ L_KV-Ll~!.t.1'ri--:

Tire No, 8 7. 75-14 Bias Ply (smooth) 53 l~ater Depth - 0,33 in.

Wheel Load - 1085 lbs.

52

51

50 0 ~ 49 .c "" 0 g

'-' ., 48 + 0 '" '" "" G

""" UJ 47 <£> ., " ::l 0 46 .... '-'

G A o--45

44 C::. Inflation Pressure

0 36 psi

43 8 · 30 psi A 24 psi

42 I A - 18 psi

10 20 30 40 50 60 7 8 90 100

% Spin-Down

FIGURE 15. EFFECT OF VEHICLE GROUND SPEED ON WHEEL SPIN-DOWN FOR HOT MIX PAVEMENT.

62

60

58

56

~

.c p.

54

" ~ '1::1

'" 52

'" 0. c.n "' 0

50 '1::1

"' ::l 48 0 ,_.

"' 46

44

42

40

Tire No. 4 F70-14 Wide Tire (Full Tread Depth) Water Depth - 0.33 in. Hheel Load - 1085 lbs.

-----0

0

0---------0 --------

------------------------- Q

&. ------

--0

0 ---

--

0 ---------

/;:;.

£\--

0

--------- ll\

------------------

0

------ £:. ---- - . - -----

------- ---. -

Inflation Pressure

0 36 psi 8 30 psi {;:;. 24 psi

-•-18 psi

10 20 30 40 50 60 70 80 90 100

% Spin-Down

FIGURE 16. EFFECT OF VEHICLE GROUND SPEED ON WHEEL SPIN-DOWN FOR JENNITE PAVEMENT.

1 1'TGUKt. · r o. r. r r EGTcJr-vErn-.:;-cic~GKouniT-:>PlcED-ON-wn~:;tL · SPTN"--iJOwN- ~-uK--~rENNT'l'E PAVEMENT.

57

56

55

54

53

52 ~

.c "' 51 13 ~

'1:l 50 Q) Q)

"' Cfl 49 '1:l

"' 0: ~ " 48

0

'" '-' 47

46

45

44

43

42

Tire llo. 4 F70-14 Wide Tire (Full Tread Depth) Water Depth - 0.40 in. Tire Pressure - 18 psi

0 / ----0~

ro 0 3"0 0 5

% Spin-Down

0

0

I 0

I 0

/ 0

/ 0

6"0 0 8ll 0

riS:JRE 17. EFFECT OF VEHICLE GROUND SPEED ON lolllEEL SPIN-DOWN FOR JENNITE PAVEl·!E:IT.

100

0"1 N

51

50

49

48

47

? 46 !§" ~

"0 45 QJ QJ .,.

Cll 44 "0 § 2 43 '-'

42

41

40

39

Tire No. 8 7. 75-14 Bias Ply (Smooth) Water Depth - 0.40 in. Wheel Load - 1085 lbs. 0 ----

0 EJ

EJ Ill

--- 8

-.-Inflation Pressure

0 36 psi 8 30 psi 8 24 psi

-·-18 psj

10 20 30 40 50 60 70 80 90 100

% Spin-Down

FIGURE 18. EFFECT OF VEHICLE GROUND SPEED ON \ffiEEL SPIN-DOWN FOR JENNITE PAVEMENT.

62

60

58

56 ~

.<:::

54 0. E ~

" 52 QJ QJ 0.

V1 U1 w "0

50 <:: ::l 0 s..

<.!l

48

46

44

42

Tire No.1 7.75-14 Bias Water Depth - 0.40 in. Wheel Load - 1085 lbs.

--IYL Ll..:;.u'l:;----.n-.cLv·-u\Jwr~·- r·o~:C1'11'n-r.r::;·---£"A v l!.I'TJSrf""r~-

Ply (Full Tread Depth)

0 --------6 0

0 -·-

== 0 0 0---·-·

0-·-

~ -·- 6 __........ Inflation Pressure

6 ~

~ 0 36 psi o 30 psi 6 24 psi

-·- -·-.............

5

-0-18 psi

10 15 20 25 30 35 40 45 50 55 60

Spin-Down (%)

FIGURE 19. EFFECT OF VEHICLE GROUND SPEED ON WHEEL SPIN-DOWN FOR LONGITUDIMALLY GROOVED CONCRETE PAVEMENT.

65 70 75 80

~

-<= c. E ~

"0 ClJ ClJ c. Vl

"0 ..,. <: :::;, 0 ,_

<!>

58

56

54

52

50 1-

48

46

I

44 I

Tire No. 3 7.75-14 Bias Ply (Smooth Tread) Water Depth - 0.40 in. \Jheel Load - 1085 lbs.

0

0 0

Q -[!]-

0

- ·--·- -----8--

42 t- 8

4Qc 1- --·-

38 -~-

'

10 20 30 40

G

0 [!]

8 6

6

Inflation Pressure

G 36 psi [!] 30 psi 6 24 psi

18 psi

50 60 70 80 90

SPif'J-DOtJN-: FOR

10

Spin-Down (%) l=1.GUR£ 2.0.

~

20 30 40 50 60 70

Soin-Do~m (%)

FIGURE 21. EFFECT OF VEHICLE GROUtlD SPEED Drl HHEEL SPIN-DOim FOR LONGITUDHIALL Y GROOVED CONCRETE PAVE!·1ENT.

80

~

.<: Q_

E

-o (!) (!) c. (/)

"' -o <:::

"' 0 s...

""

64

62

60

58

1_. _

56

0 54 ~ 8

52 r 0

50 I

Tire No.4 F70-14 Bias Ply Hide Tire (Full Tread) Water Depth - 0.25in. Wheel Load - 1085 lbs.

0 _...-G)

8

G

--- /B G

6/ Inflation Pressure

481--·- / 0 36 psi

GJ 30 PSi

46 1- -·6 8 24 psi

18 psi 44

5 10 15 20 25 30 35 40 45 50

Spin-Dorm (%)

55 60

01 .._,

70

65

60

~ 55 .<= 0. E

-a QJ QJ 0.

(/)

-a <=

"' 0 '-

<.!>

50

45

40

35

30

25

---sprn-Dovln \%Tc

FIGURE 22. EFFECT OF VEHICLE

Tire No. 9 F78-l4 Bias Ply Glass Belted (Smooth Tread) Hater Denth - 0.33 in. Wheel Lo~d - 1085 lbs.

0 0 0 0

[!] 0 0

I -8--8 8 --------------~6 I

-86

_____ 8

Inflation Pressure

10 20 30 40 50 Spin-Down (%)

60 70 80

FIGURE 23. EFFECT OF VEHICLE GROUND srEED 0'! 1/ilt.:EL SPIN-DO\IN FOR LONGITUDINP.LL Y GROOVED CONCRETE PAVEHEiiT.

0 35 rsi

0 30 psi

!:::. 24 psi

18 psi

90 100

/

(.}1

O:J

70

65

~ 60 .<::

. 0. E ~

55 "0

"' "' 0. V) 50 "0 c :::l 0 ,_ 45 '-"

40

35

-----------'-------•-------""

0 0

Q

Tire No. 10 195-14 Steel Belted Radial (Full Tread) Hater Depth 0.40 in. Hhee l Load - l 085 l bs.

~8 -·--~ __:._.::.--8

8-----L:J &

. ----·----. __.:---------6-------- . --·- Inflation Pressure

G 36 psi

Q 30 psi

!;:, 24 psi

18 psi

5 10 15 20 25 30 35 40 45 50 55

Spi n-D01~n (%)

FIGURE 24. EFFECT OF VEHICLE GROUND SPEED ON VJHEEL SPIN-Oat-IN FOR LONGITUDINALLY GROOVED CONCRETE PAVEMENT.

60

WarPr nPnrh - n ;,n ~~

~

·rl UJ 0. ~

Q) ... ::J UJ UJ

01 Q) <!) ...

p.,

Q) ... •rl H

38

36

34

32

30

28

26

24 I_.,.

22

20

18

Tire No. 7 7.75-14 Bias Ply (Full Tread Water Depth - 0.40 in. \~eel Load - 800 lbs

0 ~;:,/ /

-·-

/ /

/

/

/ 0 "/ /=

[!)

/ -·- 10% Spin-Down

0 32% Spin-Down

0 60% Spin-Down

!;:, NASA Equation

1 A 64

Ground Speed {mph)

FIGURE 25. COMPARISON OF EXPERI:fE"TAL RESULTS TO NASA EQUATION FOR CONCRETE PAVEME:;·r .

~ .... "' p. ~

<J) .... ::>

"' "' <J)

()) .... 0 "'

<J)

.... .... !'-<

38

I 36 I-

34 I-

32 ~

30 ~ 28

26

24

I 22

20

18

Tire No. 8 7. 75-14 Bias Ply (Smooth) Water Depth - 0.40 in. Wheel Load - 800 lbs

I

I

;fu;fu

(:)1

I

I

~

r.JI 0/ ~:/ /

I / I /

/ !8

/ / 0 32% Spin-Down

&/ [!] 60% Spin-Down

0 100% Spin-Down

/ 8 NASA Equation

36 38 40 42 44 46 48 50 52 54 56 58 60 62 64

Ground Speed (mph)

CONCRETE PAVEMENT •.

T·{.,..a 1\T.-. t:;: 7 7C::. _1/. n.:r __ .,.,.,_ ..-.., .... ~

38

36

34

32 ~ .....

(/)

-.:;:30 <1l H

" "'28 (/)

<1l H

0\ "" ~

'"26 H ..... H

"1 22

20

18

F"lGlJRE 26.. COMPARISON OF

Tire No. 5 7.75-14 Bias Ply (Full Tread Der~b) · Water Depth - 0.40 in. Fheel Load - 1085 lbs

El

GJ /0 &/

/

44 45 46 -+i 48 49 so 51 52

/

/ /

53 54 55 56

Ground Speed (mph)

/ 8

/ /

8

10% Spin-Down El 32% Spin-Down

0 60% Spin-Down

& NASA Equation

57 58 59

/ &/ 0 /

/

60 61 '? ~~

FhT':.;: 27. CONPARISON OF EXPERL-IENTAL RESULTS TO NASA EQUATION FOR CONCRETE PAVEMENT.

~ ..... (I} p. ......

"' " " (I}

"' (I} N Q)·

" "" 0)

" ..... [,.<

38

36

34

32

30

28

26

Tire No. 4 F70-14 Wide Tire (Full Tread Depth) Water Depth- 0.70 in. Wheel Load - 1085 lbs.

/

-·- ' G/8 /

24r-:;;· _ / 0

EJ/l::, / /-"'

22 I

20 I

18

/ El /l::,/0/

/

/ /

0

10% Spin-Down El 32% Spin-Down

0 60% Spin-Down

8 NASA Equation

l__ -- ....... ..... C."' C..'l {.,/,

·SURFACE TREATMENT ..

'T'i ... L:> l\7..-. 0 ..., "7t:: ,,_

~

·.-< Ul

'"' ~

"' ... "' Ul Ul

0"> "' w ... '"' "' ... .....

E-<

Ground V"l.CUR:E. 2.8 .. COl'rPA:'RLSOH OF EX"PERil!ENTAL RESULTS

40

38

36

34

32

30

28

26

24

22

20

18

~ :· ; . •"

Tire No. 8 7.75-14 Bias Ply (Smooth) Water Depth- 0.70 in. \llieel Load - 1085 lbs

8 ~ 0 / / / /

47 48 ~9 50 51 52 53

// [;) 0/~

~ ~

/ G

/ &0

/

-·- 10% Spin-Down G 32% Spin-Down

0 60% Spin-Down

b. Nasa Equation

54 55 56 57 58 59 60 61 6~

Ground Speed (mph)

FIGURE 29 .CO~~?,\R:CSO~l OF EXPERIMENTAL RESULTS TO NASA E')UATIO:i FOR SEAL COAT SURFACE TREATMENT.

~

·..l {/) p.

~

OJ ,., " {/) {/)

OJ ,., p.

OJ ,., ·..< E-<

36

34

32

30 .J-

28

26

24 .j...

Tire No. 2 7.75-~4 ~ias Ply (Half Tread Depth) Water Depth - 0.40 in. Wheel Load - 1085 lbs. % Spin-Down - 10%, 32%, 60%

. -·- 0

0

0

0

/ /

8

0 /

8

/ /

/ 8

/ /

-·- 0

"t/ // ,

-· -10% Spin-Down El 32% Spin-Down 0 60% Spin-Down 8 NASA Equation

20

18

l 1 1 1 I I I ~ t ;' 1 1 1 1 I I I I I I I t !_ .... ~ ... ..., ~o !;a c.n hl h73 6

Ground Speed (mph)

TO NASA EQUATION FOR HOT MIX PAVEMENT. \:;~'·''''/"

~ .... Ul p. ~

"' .... ::>

"' Ul Ul Ul

"' ....

"" "' .... .... E-<

36

34

32 t-

301

"t 26

24!

22

20

18

FIGURE 30. COMPARISON OF EXPERIMENTAL RESULTS TO NASA

Tire No. 4 F70-14 Hide Tire (Full Tread Depth) I Water Depth - 0.40 in. Wheel Load - 1085 1bs. % Spin-Down - 10%, 32%, 60%

/ -·-

-·-

I I

0

I

E)

0

I '

I I I// - ·-

I

0

0

I

/; /

80

0 A

1/

I 0

/ A

/ /

/

A/ /

-·-10% Spin-Down El 32% Spin-Down 0 60% Spin-Down 6 NASA Equation

"7 I I / I

~~~~~~~r-~~-r~_,--r-~~-r-+~~ 3~ 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 . 66

Ground Speed (mph)

FIGURr: 31.. CONPARISON OF EXPERWE~lTAL RESULTS TO NASA EQUATION FOR HOT MIX PAVE!1ENT.

36

34

32

30 ~

·..<

"' .,. ~

Q) 28

'"' " "' "' Q) 26 '"' "' Q) ...

·..< 24 E-<

22

20

18

Tire No. 7 7.75-14 Bias Ply (Full Tread Depth) Water Depth - 0.40 in. \olheel Load - 1085 lbs. % Spin-Down - 10%, 32%, 60%

0 0

///

- ·- ,EJ

/

6

/

34 36 38 40 42 44 46 48 50

0

/ /

52

Ground Speed (mph)

/

54

/ lJ

/ / 0

/ /

/

d /

6 /

56

-. -LO% Spin-Down El 32% Spin-Down 0 60% Spin-Down 6 NASA Equation

58 60 62

TO NASA EQUATION FOR HOT MIX PAVEMENT.

64 66

~

•ri lfJ p. ~

<JJ ... ::> lfJ lfJ <JJ

"' ...

...... "' <JJ ... •ri H

FIGURE 32. COMPARISON OF EXPERIMENTAL RESULTS

Tire No. 7 7.75-14 Bias Ply (Full Tread Depth) 36 L Hater Depth- 0.33 in.

\Vheel Load - 1085 lbs. % Spin-Down - 10%, 32%, 60%

34

32

30

28

26

24

22

EJ

/ /

/

" 20

18

43 44 45 46 47 48

GJ

0 ~ /

/

/

49 so 51 52

/

0

/ /

53 54 55

Ground Speed (mph)

/

r::J

/~

56

/ 0

'

/ /

/

57

-.-10% Spin-Down 8 32% Spin-Down 0 60% Spin-Down 8 NASA Equation

58 59 60 61

FIGURE 33. CO:.!PARIS0<1 OF EXPERU1ENTAL RESULTS TO :;ASA EQUATio:l FOR HOT MIX PAVEl~E:;T.

/ 8

62 63 64

36 1 Tire No. 4 F70-14 Wide Tire (Full Tread Depth) / / / Water Depth - 0.40 in. -.- 0 0 8 Spin-Down - 10%, 32%, 60%

/ // /

34 I / / 32 I / / / /

~ 30 G 0

/ .... -·- 8 Ul / 0. ~

Q) 28 / H

" Ul Ul / Q) 26 Q) H

00 p.,

Q) / H .... 24 H -·- G m

/ -·-10% Spin-Down Gl 32% Spin-Down

22 I / /

~/ G> 60% Spin-Down ~ NASA Equation

zo I / / / /

18 I _./

-·- EJ8 G / / /

41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62

Ground Speed (mph)

EXPERIMENTAL RESULTS TO NASA EQUATION FOR JENNITE PAVEMENT.

36

34

32

30 ~

·.-<

"' " ~ 28 "' ... ~ {/) {/)

26 "' ()) ... <D 0-<

"' ... 24 ·.-<

H

22

20

18 T

FTGORE j4. COMPARISON OF EXPERIMENTI\L--KESULTS-TO~~AEQilliTHJ~JW!CJENNTl'E PAVEMt:NT.

Tire No. 5 775-14 Bias Ply (Full Tread Depth) Hater Depth - 0.40 in.

/ -·- [;]

/ / 0

Spin-Dmm - 10%, 32%, 60% /

/

42

0 0 !1:. /

/

0

/

/~ .,....-'"

/ [;]6 / 0

43 ~~ 45 46 47 48 49 50 51 52 53 44

Ground Speed (mph)

0

/

55

~ /

/

/ /

- ·-10% Spin-Do<m · 0 . 32% Spin-Down 0 60% Spin-Down ~ NASA Equation

56 57 58 59 60

FTGrR~ 35. COHPARJSO:; OF E:(PERIHENTAL RESULTS TO "ASA EQUATION FOR JENNITE PAVEMENT.

61

6

'0 0.:.. 63

~

·.-I <Jl p. ~

QJ ... :l <Jl <Jl QJ ....,

0 ... p.

QJ ... ·.-I H

Tire No, 5 775-14 Bias Ply (Full Tread Depth) 36 I Water Depth - 0.33 in.

34

32

30

28

26

24

22

20

18

Spin-Dmm - 10%, 32%, 60%

-·- GJ / / /

0 IJ::. /

- •- 10% Spin-Down 8 32% Spin-Down 0 60% Spin-Down /]:;. NASA Equation

42 43 44 45 46 47 48 49 50 51 52 53 . 54 55 5b 57 58 59 60 61 62

Ground Speed (mph)

EXPERIMENTAL RESULTS WITH NASA EQUATION FOR JENNITE PAVEMENT.

38

36

34

32

~

·~ Vl 30 n ~

QJ

'- 28 :::! Vl Vl

'.J QJ ~ '-

0.. 26 QJ

'-·~ 1-

24

22

20

18

36

r I GORE 36. COMPARISON llYTXPERlTIENT~RTSUI:TSin~ll-NASAEQUATION FOR JENN1TE ,PA.'VEMENT.

~;; :<-·i·;;

Tire t!o. 9 F78-l4 Bias Ply Glass Belted (Smooth) Water Depth - 0.25 in.

0 Hhee1 Load - 1085 1 bs.

8

38 40 42 44

0 G]

/ /

/

46 48

I

El

/ /

6./ /

/

50 52

Ground Speed

54

(mph)

El

/ /

/ 8

/

56

0 G]

8

58

/ ./

A

10% Spin-Down

32% Spin-Down

60% Spi n-Dovm

NASA Equation

60 62

FIGURE 37. C0~1PARISON OF EXPERH1ErHAL RESULTS TO NASA EQUATION FOR LONGITUDHlALL Y GROOVED CONCRETE PAVEt·1EN T.

64 66

38

36

34

32 ~

·~ Vl

30 D.. ~

QJ

'-28 ::::>

Vl Vl QJ ..._, '-

0...

26 N

QJ

'-·~ 1-

24

22

20

18

I

36

Tire No. 9 F78-l4 Bias Ply Glass Belted (Smooth) Hater Depth - 0.40 in. Wheel Load - 1085 lbs.

-·-G Q

0 GJ 8

38 40 42 44

-·-0 [!]

/ /8

/ /

/

46 48 50

Ground Speed

52

(mph)

0

/ /

54

El

8 /

56

/ /

/

8 /

- ·- 10% Spin-Down 0 32% Spin-Down E1 60% Spin-Down 8 NASA Equation

58 60 62 64

38

36

34

32 ~

·~ til

30 c.. ~

QJ s..

28 ::J til til QJ

" s.. w c:... 26

QJ s.. ·~ 1-

24

22

20

18

FlG.URE 38.

Tire No. 4 F70-l4 Bias Hater Depth - 0.40 in. 11heel Load- 1085 lbs.

36 38 40 42

<lTD.

TS TO NASA EnUATION FOR .

Ply lJide Tire (Full Tread)

-·- 0 &.

-·-

/ ,-._· / \!.I&

44 46

/

48

/ -·- \!) $

/ /

/ 0 &. Q

/

/

50 52 54

/

/

56

Ground Sneed (mph)

/

0

Q

/;':,

58

/

/ /

10% Spin-Down 32% Spin-Down 60% Spin-Down NASA Equation

60 62

FIGURE 39. C0'1Pf..RISON OF EXPERH~E:ITAL RESULTS TO ::.n.Sl'1 E'lUATION FOR LQ;IGITUDINALL Y GROOVED CONCRETE PAVEf.1E1iT.

64

..., ""'

~

" .... ~

0.8

0.6

.c 0. 4 '-'

"" aJ Q

... aJ '-'

"' ::;: o.

Tire No. 8 7.75-14 Bias Ply (Smooth) 10% Spin-Down Pavement No. l (Concrete)

1085 0

8

Hheel Loads ( lbs)

800 -0- 36 psi

-8- 30 psi

6 -6- 24 psi

-&- b. -EJ-8 -0- 0

-~- & -G-El -0- 0

\~~\~ -b.- 8-8- El -0- 0

L I I

36 37 38 39 40 41 42 43 44 45 46 47 48 49

Ground Speed (mph)

FIGURE 40. EFFECT OF WATER DEPTH AND HllEEL LOAD ON GROUND SPEED TO CAUSE 10% SPIN-DO\-;~;.

Hheel Load ( lbs) Tire No. 7 7. 75-14 Bias Ply (Full Tread Denth) 10% Spin D01om 1085 800 Pavement No. 1 (Concrete) G -0- 36 psi

(!] -EJ- 30 psi

8 -8- 24 psi

18 psi Not Attempted

-0.8

I 8 8 0

-8- I -EJ- -0-

0.6

.._, ~ Ul '" ·rl ~

..c .., ~ -8- -[!]-p. 0.4 8 0 -0-

QJ

~ \ ~- ~ p

.... QJ .., m ;3 -8- (!] -(!]- -0-

0.2

44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62

Ground Speed (mph)

FIGURE 41. EFFECT OF HATER DEPTH AND h'HEEL LOAD ON GROUND SPEED TO CAUSE 10% SPIN-DOh'N.

0.8

0.6 ~

"' .., .... , ~ .c '-' 0. Q)

"" o.t .... Q)

'-'

"' ~

0.2!-

Hheel Load - 1085 lbs 10% Spin-Down Pavement No. 1 (Concrete)

-&-

-·- 8

\ / & -·-

~

41 42 43 44 45 46

----'

Full Treacl D('pth

T:::_dc Tire Bias Ply

0 -0- 36 psi

8 -0- 30 psi

& -&- 24 psi

18 psi

-8- -0-

' -&- 8 0 -I!J- -0-

~ \ ~ 8 -[!):!) -0-

~0 ~0

47 48 49 50 51 52 53 54 55 56 57 58

Speed (mph)

0.8

~

.~ 0.6 ~

".c ""' 0.

OJ A

~ 0.4 .., "' ::;::

0.2

Ground Speed (mph)

V"I..C.\J'R'E 'F_"F'FE.C'1." OF HATER DEPTH AND TIRE ASPECT

Full • Tread Deptlt Smooth

7.75-14 Bias Ply 0 -0- 36 psi

IVheel Load - 1085 lbs 0 -0- 30 psi

10% Spin-Down Pavement No. 1 (Concrete)

& -8- 24 psi

& 8 0

-&- -0- -0-

\"G -&- -El- -0.-

~~ &- -EI- -0- El

B

\

41 42 43 44 45 46 47 48 49 so 51 52 53 54 55 56 57 58

Ground Speed (mph)

FIGURE 43. EFFECT OF \VATER DEPTH AND TREAD DEPTH ON SPEED TO CAUSE 10% SPIN-DOhTN.

0.4

~

" .... 0.3 ~

,.c: '-' p,

"' -...J "' 00 H

"' '-'

& 0.2

0.1'

Tire No. 1 7. 75-14 Bias Ply (Full Tread Depth) Wheel Load- 1085 lbs. 10% Spin-Down

C:,. [!]

( [!]

\ &.

\ C:,.

0

\ 0

[!] 0

Inflation Pressure

0 36 osi 8 30 psi ~ 24 psi

18 psi - No Spin-Down

42 43 44 45 46 47 48 49 so 51 52 53 54 55 56 57 58

Ground Speed (mph)

FIGURE 44. EFFECT OF WATER DEPTH ON SPEED TO CAUSE 10% SPill-DOWN - HOT MIX PAVEMENT.

0,4

~

" •rl 0.3

.<=: '"' 0. OJ ...... "" <0 H OJ

'"' " :;: 0.2

0.1

Tire ilo. 3 7. 75-14 Bias Wheel Load - 1085 lbs. 10% Spin-Down 8

40 41 42 43

Ply (Smooth)

0

-~ 0

44 45 46

------------ -----,v---o----- ~ ~,----..,..-.._.. T> .-,------ "--- ---------------,.;-;ce>,·v- ..O.L-~=~-,--:<:--;.---

()

()

0 0

~0

47 48 49 50 51

Ground Speed (mph)

Inflation Pressure

0 36 psi G 30 psi 8 24 psi

0

l8 psi - No Spin-Dmm

52 53 54 55 56

FIGURE 45. EFFECT OF HATER DEPTH ON SPEED TO CAUSE 10% SPIN-DOHJ -HOT MIX PAVEMENT.

Tire No. 1 7.75-14 Bias Ply (Full Tread Depth)

0 41. Hheel Load-1085 lbs. 8 0 . "' '';".'""" } . - ( \ ~ -·- 8 Q . " \ \ ,::. 0.3

.c '"' .,. QJ 0 co Q

0 .... \ \ Q)

'"' ~ 0.2

8 0

0.1

41 42 43 44 45 46 47 48 49 50

Ground Speed (mph)

51 52

0

\ 0

\ 0

\ 0

Inflation Pressure 0 36 psi [J 30 psi 8 24 psi -·-18 psi

53 54 55

- JENNITE PAVEMENT.

56 57

0.5

0.4

<= 0.3 ·~ ~

00 -<= +' 0. QJ

0

>-QJ 0.2 +'

"' 3:

0 .l

36

FIGURE 46 , i:FFECT OF WATER DEPTH ON SPEED TO CAUSE

Tire No. 4 F70-l4 Bias Ply Hide Tire (Full Tread) Wheel Load - 1085 lbs. Spi n-D01·m - l 0%

0

) 0 lJ 8

Inflation Pressure 0 36 psi

38 40 42 44 46 48 50 Ground Speed

52

(mph)

0

8

54

30 psi • • 24 ps1

18 psi

56 58

FIGURE 47. EFFECT OF \lATER DEPTH 011 SPEED TO CAUSE 10% SPIN-DOHN -LONGITUDINALLY GROOVED CONCRETE PAVEMENT.

60 62 64

0. 5

0.41-

~ 0.3 <=l

•..! OJ ~ N

-"' .._, c. QJ Cl

~ 0.2 .._, "' ~

0. l

Tire No. 9 F78-l4 Bias Ply Glass Belt (Smooth Tread) Wheel Load - 1085 lbs. Spin-Down - 10%

0 b. -\ \ 0

\ 0

\ 0

39 40 41 42 43 44 45 46 47 48

Ground Speed (mph)

HI\TER DEPTH Oil

0

\ 0

0

,o Inflation Pressure

0 36 osi

0 30 psi

b. 24 psi

18 psi

49 50 51 52 53 54

52

50

48

46 ~

-"" ~ 44 ~

00 "0 w 2i 42 c. Vl

"0

5 40 0 s... '-"

38

36

34

FIGURE 48. EFFECT OF \~1\TER DEPTH ON SPEED TO CAUSE 70% SPIN-D0!4N -LOf.IGITUDINALLY GROOVED CONCRETE PAVEMENT.

Tire No.3 7.75-14 Bias Ply (Smooth Tread) Water Depth - 0.33 in. Wheel .Load - 1085 lbs.

-D-O ---15----=::::::====-======-_R-

-o---A ~--- -l-6-----6- 8 -

-·--

Inflation Pressure

1972 1973

-0- 30 psi 0

-6.- 24 psi 6. I 18 psi -·- -·-

10 20 30 50 60 40

Spin-Dm'in (%)

FIGURE 49. REPEATABILITY CHECK OF DATA FOR JENNITE PAVH1ENT.

70

64 ·-

62

60

58

~

.<::

Q_ 56 ·-E ~

00 ""0

54 ..,.

QJ Q) Q_

V1

""0

52 t: :::> 0 '-

<!l

50

48

46

Tire No. 1 7.75-14 Bias Ply (Full Tread) ~!ater Depth - 0.33 in. Wheel Load - 1085 lbs.

[J

-0-

& -6-

10 20

-r:J-[::J

30

Inflation 1972

Pressure 1973

-GJ- 30 psi GJ

-8- 24 psi 8

40 50

Spin-Down (%)

[:]

60

PAVH1ENT.

70

0.8

~

" .... 0.6 ~

..c: ~

"" <l)

co p 01

" <l) ~ <tl 0.4 :;:

0.2

46

FIGURE 50. REPEATABILITY CHECK OF DATA FOR CONCRETE PAVH1ENT.

Tire No. 1 7.75-14 Bias Ply (Full Tread Depth) Hheel Load - 1085 lbs 10% Spin-Down

-&- -[!]-

& 0

~& \ [!]

~& \ 0""-------0

47 48 49 so 51 52 53 54

0 \ 0

Pavement

Ill //2 0 -0-

0 -0-

& -&-

\ 0""-­

"-...__0

55 56

Ground Speed (mph)

57

36 psi

30 psi

24 psi

18 psi

58

FIGt:RE 51. COHPARISON OF CONCRETE Ai!D SEAL COAT SURFACE TREATifENT.

-0-

59 60 61

0.8

0.6 ~

.:: .... 0 ~

0 ..c: .., "' Q)

<=> 0.4 .... Q) .., "' ::;:

I 0.2

Tire No. 4 F70-l4 Hide Tire (Full Tread Depth) Wheel Load - 1085 lbs 10% Spin-DoHn

-8-

8~ 8:, -·-~ GJ -·-\

42 43 44 45 46 47 48 49

Pavement

111 112 0 -0- 36 psi

GJ -[!]- 30 psi

8:, -8:,- 24 psi

-·- 18 psi

-GJ- -0-

""------------ 0 ~ - GJ-

0~ G--.........___ ~0

GJ

so 51 52 53 54 55

Ground Speed (mph)

SURFACE TREATMENT.

-0-

-8-

56 57 58 59 60

0.4

~

" 0.3 •ri ~

"" w p. QJ

0

... 00 QJ " w

0. 2 "' ;3:

0.11

FIGURE 52. COHPARISON OF CONCRETE AND SEAL COAT SURFACE TREATMENT.

Tire No. 4 F70-14 Wide Tire (Full Tread Depth) Wheel Load - 1085 lbs 10% Spin-Do"n

. ~

-·-A- I \~-A -·- I

-B- B\ -0~ 0- .

-0-. 0 ~ ~

6. " -~"0 -0-'- B "

-0- ..... 0 -0-

Surface Ill

36 psi 0 30 psi [J 24 psi 6. 18 psi

38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54

Ground Speed (mph)

FIGL'RE 53. COI-lPARISOC'J OF CONCRETE A'lD HOT NIX PAVEHEcJTS.

0

Surface l/3

-0--[J-

-6.-' -·-1

55 56 57 58

0.4

~ . " ..... 0.3 ~

.c w 0. Q)

co "" co ... Q) w

"' 0.2 ;,

0.11

Tire No. 3 775-14 Bias Ply (Smooth) Wheel Load - 1085 lbs 10% Spin-Down

-~- -0- /!§)- 0 0

~\ \\ -\\ -\ Q~'0 -6-0- -0- 0 0

J \\ ~ -&- . -0-0- 0 0

Surface 1/3 Surface 114

36 psi 0 -0-30 psi El -El-24 psi 6 -6-

I•

18 psi -·- I

37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57

Ground Speed (mph)

AND JENNITE PAVEMENTS.

00 \.0

42

F"LGURE 54, COMPAR"LSON OF HOT MIX AND JENNITE PAVEMENTS,

Tire No. 9 F78-14 Bias Ply Glass Belted (Smooth) Tire No. 10 195-14 Steel Belted Radial (Full Tread) Water Depth - 0.33 in. Wheel Load- 1085 lbs.

36 L Spin-Down - 10%

·~

~30 ~

QJ

'-::J V> V> QJ

'-0. 24 QJ

'-·~

!--

18

n

I !:i 0 -·- /v

/ Tire // No. 9 ~lo.

0 0 v- !:i v

X!

0

10 Surface

No. 1 Concrete

No. 4 Jennite

0

Texture

0.018

0.020

No. 5 Grooved Concrete D.047

40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Ground Speed (mph)

FIGURE 55. lmi SPIN-DOl1ii FOR T'IO TIRES Af!D THREE SURFACES AT SELECTED TIRE PRESSURES.

42

36

~

·~ Vl 30 D.. ~

QJ <D '-0 ::> Vl Vl QJ

'-o._

24 QJ

'-·~ 1-

18

Tire No. 4 F?0-14 Hide Tire (Full Tread) Water Depth - 0.40 in. Hheel Load - 1085 lbs.

/l//-0 ° 6

/I; 0 -EJ~

38 40 ° 42 44 46 48 50 52 54

Surface Texture

EJ No. 1 Concrete 0.018 I No. 2 Seal Coat 0 0146 I 0 flo. 3 Hot Mix 0.033

6 No. 4 Jennite 0.020

·- t-:o. 5 Grooved 0.047 - Concrete

56 58 60 62 64 66

Ground Speed {~ph)

70% SP I N-DOl·IN.

68

FIGURE 56. EFFECT OF SURFACE AND TIRE PRESSURE AND GROUND SPEED FOR 10%

Surface No, 4 Wheel Load - 1085 lbs. 10% Spin-Down

0. 411 I I I i

-& 0 -1!::.- -0- 0 -Q- -0- -0-

( vii I \ \ /I I

I i 0.3 +\ r 0$.- -0- 0 -8- -0-0-

\\' ( \ 1\1 I I

'"' Q !~ -L:B [J- 0 -8-0-

~

i 0.2 I

1

~\ I~ I \ \(I

0 -0-1!::.- 0 -ot:J-I I

Tire Ill

0.1 36 psi 0 30 psi 0 24 psi 1!::. 18 psi

43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59

Ground Speed (mph)

FIGURE 57. COHPARISON OF BIAS PLY TIRES (1, 5, & 7)

, I

-0-

115

-G--8--1!::.-

1\1 -0-I 117

I -o--6-

' -ti-l I

-j-

60 61 6"2 63

---··~-----··· ····--·-----·--···

36 38 40 42 44 46 48 50 52 54 56 58 60 62 64

Ground Speed (mph)

(9,10)

lO w

0.5

0.4

.;: 0. 3

.<:: +-' D.

"' 0 ,_ "' +-'

"' ::0: 0.2

0. 1

0.0

FIGURE 58. C0~1PARISON OF BELTED TIRES TESTED (9, 10)

",~·.·

Tire No. 4 Wide Tread (Full Tread Depth) Tire Pressure - 24 psi

Ungrooved Concrete

44 46

10% Spin-Down

Grooved Concrete

48 50 52

Ground Sreed (mph)

FIGURE 59. COMPARISON OF UNGROOVED AND GROOVED CONCRETE SURFACES WITH VARIOUS WATER DEPTHS.

54 56

0.5 10% Spin-Down Tire Pressure 24 psi

0.4

Tire No. 4

r,r ~ <.0 ~ Hi de Tire

..,. Tire tlo. 9 (Full Tread Depth)

Glass Belted (Smooth)

'-OJ 0.2 ~

"' 3:

0. l

0.0

42 44 46 48 50 52 54

Ground Speed (mph) EFFECT WATER DEPTH ON GROOVED CONCRETE SURFACE.

42

36

~

·~ Vl

30 Q_ r ~

<D r.n QJ

s.. ::s Vl Vl QJ s..

CL

QJ s.. 24 ·~ 1-

I 18

40

-------···-- -f:irtiuna S)Jeecr rmprr/

l'lGURE 50. EFFECT OF WATER DEPTH ON GROOVED CONCRETE SURFACL

Tire tlo. 9 Hide Tread (Full Tread Depth) Water Depth 0.40 in. 10% Spin-Down

Ungrooved / / / Concrete Seal Coat

Grooved Concrete

//

44 48 52 56

Ground Speed (Mph)

FIGURE 61. COMPARISON OF UNGROOVED CO~CRETE, GROOVED CONCRETE A~D SEAL COAT SURFACES.

60 64

70

60

50

40

20

10

0

0

•

Tire No. 8 7.75-14 Bias Ply-Smooth

Speed Limit for Major Rural Highways --- -- - lligh Texture (0.1"'5 in.)

---Low Texture (O.Olil in.)

Pressure 27 psi, 50 th Percentile 10% Spin Dmm

0.2 0.4 0.6 O.B 1.0

Water Depth (in.)

FIGURE 62. EFFECT OF TEXTURE ON HYDROPLANING.

96

60

ays

.<::

"'- 50 E

"0 QJ QJ Cl. Vl

"0 t:: ::l 0 ,_ '-"

40

0

0

------------------ ---------------- Speed Limit for Major Rural Highways

.2

Grooved Seal Coat Concrete

Jennite Concrete

Tire No. 4 F70-14 Wide Tire (Full Tread Depth) Pressure 27 psi, 50th percentile 10% Spin-Down

.4 .6 .8 1.0

Water Depth (in.)

FIGURE 63. EFFECT OF TEXTURE ON HYDROPLANING.

97

70

50

;;; 30 " 0 ,..

20

10

Jo -------------- Speed Limit for Major Rural Highways

- Psj --~Psi ---------- ........... _, ---- -

Tire No. 4 F70-14 Wide Tire (Full Tread Depth)

Low Texture, 0.018 in. 10% Spin Down

OL-------~-------L------~~------~------~ 0 0.2 0.4 0.6 0.8 1.0

Water Depth (in.)

FIGURE 64. EFFECT OF PRESSURE ON HYDROPLANING.

98

70

60

50

40

20

10

------------------------------ Speed Limit for l1ajor Rural Highways

-....... .......

---..... -

-.. --....... '

Tire 4, 7 And 8

Low Texture, 0.018 in, Pressure 27 psi, 50th Percentile 10% Spin Down

!lias Ply Full Tread Depth

Wide Tire; Full Tread Depth

Bias Ply, Smooth

0~------~-------L------~~------L-------~ 0 0.2 0.4 0.6 O.R 1.0

Hater Depth (in.)

FIGURE 65. EFFECT OF TIRE ON HYDROPLANING.

99

r--

I ___ right fro t tire

--·--· left fron tire --lC--X right rea tire

100 left rear tire

-

80 _d ~ v

I ;.... w b r:: 60 b (I) u

'"' (I)

"' (I)

:> ..... w

"' 40 ..-{

:l s :l

~ u

20

r/ v--·

h 0 A

0 10 14 18 22 26 30 34

Tire Pressure

FIGURE 66. C0!1PARISON OF TIRE PRESSURES - ACCIDENT STUDY. (ref. 25)

'""' . .,., "' ~ ',<I) ... ~

~ "' ~ 3/8

.;.::::

"' "' "" '-' 5/16 ·~ ~

•I '-'

' 'I ""' irJ -....

"' " 1/4 8 ....

~

"' irJ "' <ll [;'; 0.. 3/16

0

6 .-I

"' ~

H Ul !-< Ul 1/8

0 ... u

1/16

0 0

Design Rainfall Intensity = 1 in./hr. 99.95 Percentile Intensity Level

12 ft. 24 ft.

"L, '6 ~+WD ~-WD

6 6 Positive ~ ___:;,. Negative '-....... Water Depths - ~ Water Depths ~6

" '

0.03 0.04 0.05 0.06 0.07

Texture (in.)

FIGURE 67. COMBINATIONS OF CROSS SLOPE AND TEXTURE REQUIRED TO PREVENT SIGNIFICANT WATER DEPTHS.

101