Technical Memorandum Work Order #4-F Prepared for ... · 6 9 15 17 19 19 19 23 26 28 30 30 40 42 44 46 46 46 47 47 48 50 . LIST OF FIGURES Page ... reopening of school, the peak-hour

DEMAND MANAGEMENT FOR AM AND PM OPERATIONS 1-10 KA1Y FREEWAY TRANSI'IWAY

Technical Memorandum Work Order #4-F

Prepared for

Metropolitan Transit Authority of Harris County

Texas Transportation Institute The Texas A&M University System College Station, Texas 77843-3135

June 1990

TABLE OF CONTENTS

INTRODUCTION

REPORT ORGANIZATION

AM PERIOD OPERATING CONDITIONS

Vehicle Demands

Travel Time and Speed

Capacity Analysis

Summary of AM Peak Period Operations

OPTIONS FOR MANAGING DEMAND DURING THE AM

PEAK PERIOD

Voluntary Spreading of Peak Hour Demand

Imposing a 3 + Carpool Definition during the Peak Hour

Require Authorization during the Peak Hour

Close and/ or Meter Entrance Ramps during the AM Peak Hour

Recommendations

PM PERIOD OPERATING CONDITIONS

Vehicle Demands


Capacity Analysis

Summary of PM Peak Period Operations

OPTIONS FOR MANAGING DEMAND DURING THE PM

PEAK PERIOD

Voluntary Spreading of Peak-Hour Demands


Require Authorization during the Peak Hour

Close and/ or Meter Entrance Ramps during the PM Peak Hour

Recommendations

REFERENCES

111

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LIST OF FIGURES

Page

1. Katy Freeway Transitway, AM Peak Hour Transitway

Vehicle Utilization 2

2. Katy Freeway Transitway, PM Peak Hour Transitway

Vehicle Utilization 3

3. Katy Transitway Eastbound, AM Peak Hour Volumes, April 1990 10

4. I-10 Katy Transitway Flow Rates, Eastbound, AM Peak Period 12

5. I-10 Katy Freeway/Transitway Average Speeds, Eastbound,

AM Peak Period 14

6. Katy Transitway Westbound, PM Peak Hour Volumes, April 1990 34

7. I-10 Katy Transitway Flow Rates, Westbound, PM Peak Period 36

8. I-10 Katy Transitway Flow Rates, Westbound at Silber,

Weekday and Fridays 39

9. I-10 Katy Freeway/Transitway Average Speeds, Westbound,

PM Peak Period 41

IV

LIST OF TABLES

Page

1. AM Peak Period Vehicle Volumes, 1-10 Katy Transitway 7

2. AM Peak Hour Vehicle Volumes, 1-10 Katy Transitway 8

3. Katy Transitway Eastbound 5-Minute Flow Rates, May 1990 11

4. Results of Travel Time Studies, AM Peak Period, March 1990 13

5. AM Peak Period Sample Speed Study Results 15

6. Basic Section Level-of-Service, AM Peak Hour 16

7. Summary of AM Peak Period Operations, Katy Transitway

Post Oak Terminus 17

8. AM Travel Volumes Before and After Change in Occupancy

Requirements, Katy Freeway Corridor 20

9. Estimated Factors for Converting Unauthorized Carpool Demand

to Authorized Carpool Demand 24

10. PM Peak Period Vehicle Volumes, 1-10 Katy Transitway 31

11. PM Peak Hour Vehicle Volumes, 1-10 Katy Transitway 32

12. Katy Transitway Westbound 5-Minute Flow Rates, May 1990 35

13. Comparison of Weekday and Friday Afternoon 5-Minute Flow

Rates, Katy Transitway at Silber 38

14. PM Peak Hour and Peak Period Demands Observed at Silber 40

15. Results of Travel Time Studies, PM Peak Period, March 1990 40

16. PM Peak Period Sample Speed Study Results 42

17. Basic Section Level-of-Service, PM Peak Hour 43

18. Summary of PM Peak Period Operations, Katy Transitway

Post Oak Terminus 44

v

INTRODUCTION

Phase 1 of the Katy Transitway opened in October 1984. At that time, only

authorized buses and vans were allowed to use the transitway; fewer than 100 vehicles

used the transitway during the peak hour.

In order to address a public perception that the transitway was underutilized, the

following actions have been taken to manage vehicular volumes on the transitway:

o April 1985 -- 4 + authorized carpools were allowed to use the transitway;

o July 1985 -- authorized 4 + carpools were allowed to use the transitway with

only 3 + occupants in the vehicle;

o September 1985 -- authorized 3 + carpools were allowed to use the transitway;

o August 1986 -- 2+ carpools were allowed to use the transitway and

authorization requirements were eliminated; and

o October 1988 --between 6:45- 8:15am, carpools must meet a 3+ occupancy

requirement to use the lane.

Removing authorization and allowing 2+ carpools to use the transitway significantly

increased transitway usage beginning in 1986 (Figure 1). In addition, the completion of

Phase 2 of the transitway in July 1987 generated approximately a 15 percent increase in the

AM peak hour carpool volume; data collected in early September indicated that, with the

reopening of school, the peak-hour demand on the transitway increased by an additional

5 percent to 10 percent. Approximately 1,350 to 1,450 2 + carpools used the transitway

during the AM peak hour prior to implementation of the 3 + restriction. Demands during

the peak have effectively been controlled during the AM peak hour with approximately

1,090 vehicles observed in December 1989. The 1.5 mile Eastern Extension opened in

January 1990 and traffic demands during the peak hour have increased by only 150 vehicles

(14%) in the AM peak hour.

Vehicle demands during the PM operating period were not impacted by the 3 +

restriction imposed during the AM peak period (Figure 2). The opening of the Eastern

Extension has resulted in an approximate 15 percent increase in vehicle demands on the

1

(/) w .....J u I w > u.... 0

N 0:: w CD 2 :::::> z

Figure 1. Katy Freeway Transitway, AM Peak Hour Transitway Vehicle Utilization

KATY FREEWAY (IH 1 OW) TRANSITWAY A.M. PEAK HOUR TRANSITWAY VEHICLE UTILIZATION

----> ----> 1,750 1rR"A"NsfrwAY t:rRA"Ns~AY iO GESSNER iTo WESi BELi

iRANSITWAY 10 SH 6

EASiERN EXTENSION OPENS

I '""""WAY CAl''"" I lf<-:1 _,.;<.,T t~\~ ""'0"""' 11' '"""'~~"1 ;

1 .soo l 1 Ji \ ~f

~ ~' t, ;r -~ {f

\0\~4

lh y<, ,( ~~-.

f ,

1,250

1,000

750

500

250

0 T

OCT84 OCT85

l I

OCT86 OCT87

KATY TRANSITWAY PHASE 1, POST OAK TO GESSNER (4.7 MI.), OPENED OCTOBER 29, 1984 TRANSITWAY EXTENSION FROM GESSNER TO WEST BELT (1.7 MI.) OPENED MAY 2, 1985 OFF-PEAK, UNAUTHORIZED&: 2+ CARPOOL OPERATION BEGAN AUGUST 11, 1986 TRANSITWAY EXTENSION FROM WEST BELT TO SH 6 (5.0 MI.) OPENED JUNE 29,1987 3+ CARPOOL REQUIREMENT FROM 6:45 TO 8:15A.M. IMPLEMENTED OCTOBER 17, 1988 TRANSITWAY EASTERN EXTENSION (1.17 MI.) OPENED JANUARY 9, 1990 DATA COLLECTED BETWEEN GESSNER AND POST OAK SOURCE : TEXAS TRANSPORTATION INSTITUTE

OCT88 OCT89

LEGEND: T =TOTAL HOV VEHICLES B = TOTAL BUSES V =TOTAL VANPOOLS C =TOTAL CARPOOLS

OCT90

(/) w _j

u -:r: w > w...

w 0 0:::: w m 2 :::::> z

Figure 2. Katy Freeway Transitway, PM Peak Hour Transitway Vehicle Utilization

KATY FREEWAY (IH 1 OW) TRANSITWAY P.M. PEAK HOUR TRANSITWAY VEHICLE UTILIZATION

---> ----> 1 ,800 l 1TRiiiSiiwAY f,;;;-;,r;w., TO GESSNER TO WEST BELT

TRANSITWAY TO SH 6

EASTERN EXTEiNSION OPENS

I'

\ ~

1,600

I~

t 1,400

l-~

:r !j~~ 1-~~T--i ~. r J. ;;<. l·?~, A 1' ~~ ,_./; 'e-' \, y,fo., 1' 'f' ~ "! j'ri .~ I~ :. • 14. ~·~ '/ ref e' ·-.. i~YI~'/ v v " k

1,200

~ I NOTE : PEAK HOUR DEfiNED AS

HOUR DURING WHICH PERSON MOVEMENT IS GREATEST

1,000

800 il 600 r 400

I 200

0 T"

OCT84 OCT85 OCT86 OCT87

KATY TRANSITWAY PHASE 1, POST OAK TO GESSNER (4.7 MI.), OPENED OCTOBER 29, 1984 TRANSITWAY EXTENSION FROM GESSNER TO WEST BELT {1 .7 MI.) OPENED MAY 2, 1985 OFF-PEAK, UNAUTHORIZED & 2+ CARPOOL OPERATION BEGAN AUGUST 11, 1986 TRANSITWAY EXTENSION FROM WEST BELT TO SH 6 (5.0 MI.) OPENED JUNE 29,1987 TRANSITWAY EASTERN EXTENSION (1.17 MI.) OPENED JANUARY 9, 1990 DATA COLLECTED BETWEEN GESSNER AND POST OAK SOURCE : TEXAS TRANSPORTATION INSTITUTE

OCT88 OCT89

LEGEND: T =TOTAL HOV VEHICLES B =TOTAL BUSES V =TOTAL VANPOOLS C =TOTAL CARPOOLS

OCT90 .

transitway (1,290 vph in December 1989; 1,500 vph in April 1990) in the PM peak hour.

Queueing within the Post Oak/Eastern Extension merge has been observed to occur for

periods of time during the PM peak hour, particularly on Fridays.

The objective of the transitway is to provide a reliable, high-speed travel alternative;

the travel time savings and reliability offered by the transitway provide the incentive for

travelers to use high-occupancy vehicles. It is imperative that traffic volumes using the

transitway be managed at a level that avoid the creation of significant congestion on the

transitway.

In managing vehicle volumes on a transitway, the intent is to strike a balance

between two competing needs. First, a sufficiently high volume, probably at least 600 vph,

must be maintained during the peak hour so that the facility appears to be adequately used

to those individuals travelling in the congested freeway general-purpose lanes. Second, the

flow rate using the lane during the peak hour needs to be kept below about 1,400 vph so

that the lane operates at a high speed and offers a reliable travel time. It should be noted

that both METRO and SDHPT have agreed that high-speed and reliable trip times should

be provided on the Houston transitway system.

Managing the demand on the transitway is further complicated by at least one other

factor. Transitway facilities have exceedingly high peaking characteristics; this means that

the vehicle volume on either side of the peak hour is only about half of the peak-hour

volume. Thus, the need exists to manage the peak-hour volume without adversely affecting

the volumes on either side of that peak hour. Experience in Houston has demonstrated

that the design of the transitways (i.e., physical separation from the freeway lanes with

limited access/egress opportunities) combined with the routine enforcement that is provided

make a variety of innovative demand management strategies feasible.

There are two specific concerns to be addressed within this report: 1) continuance

of the 3+ carpool requirement from 6:45am to 8:15am; and 2) what action, if any, should

be implemented to manage demand during the PM peak period.

4

REPORT ORGANIZATION

This report is organized into two major sections. The first addresses operations

during the AM peak period, while the second section examines PM operations. This will

allow for an independent analysis of the two operating periods since each has unique

operating characteristics. Data collected by Til from January to May 1990 are used to

define the current operating conditions of the Katy Transitway. Til has prepared

numerous reports documenting operations of the transitway. The more recent reports are

listed in the reference section of this report.

5

AM PERIOD OPERATING CONDITIONS

The transitway presently operates in the eastbound direction from 4:00 am to 1:00

pm during normal work days. The HOV lane is used by buses, vanpools, and 2+ person

carpools; a 3 + occupancy restriction is presently (May 1990) implemented between 6:45 -

8:15am. The opening of the 1.5 mile Eastern Extension occurred on January 9, 1990. The

Northwest Transit Center became operational on April 1, 1990. Concerns have been

expressed by the public that the 3 + restriction is no longer necessary since a majority of

HOV users exit the facility using the Eastern Extension instead of the signalized

intersection at Post Oak.

Vehicle Demands

TTl collects vehicle and passenger data at three locations along the Katy Transitway:

East of Addicks, at the Post Oak Terminus, and the Eastern Extension. Although the data

is collected only one day each month, the values reported are representative of typical

operations for normal non-incident conditions on the HOV lane. Table 1 presents

transitway demands as observed during the AM peak period (6:00 - 9:30 am) since the

Eastern Extension opened. Total vehicle demands at Silber have been steadily increasing

since the beginning of the year. Peak period demands for those entering west of Gessner

have remained almost constant. Demand for the Gessner slip ramp entrance has increased

from 915 to 1,667 vehicles during the peak period; an increase of 82 percent. Since the

Post Oak exit demands have remained constant, the increase at the Gessner entrance is due

to an additional approximate 700 vehicles per peak period using the Eastern Extension in

April as compared to January 1990. The effect of the Northwest Transit Center on

transitway operations has been minimal. Buses accounted for only 4 percent of the total

vehicle demand during the April 1990 AM peak period; buses and vanpools comprise the

remaining 96 percent.

Table 2 presents similar data for the AM peak hour. The determination of the

peak hour was based upon the maximum vehicle demand at Silber. This was estimated

by summing 15-minute data from the Post Oak and Eastern Extension count locations; the

maximum hourly flow is reported. This should not be confused with other TTl reports

6

Table 1. AM Peak Period Vehicle Volumes, 1-10 Katy Transitway

Entering West Entering Demand Exiting at Exiting to Time Period of Gessner at Gessner at Silber Post Oak 1-10 EB

January 1990 Buses 48 34 82 7 75 Vanpools 26 16 42 18 24 Carpools 1364 865 2229 1021 1208

Total 1438 915 2353 1046 1307

February 1990 Buses 47 30 77 5 72 Vanpools 28 9 37 16 21 Carpools 1403 1097 2500 1016 1484

Total 1478 1136 2614 1037 1577

March 1990 Buses 45 47 92 5 87 Vanpools 26 17 43 18 25 Carpools 1397 1164 2561 967 1594

Total 1468 1228 2696 990 1706

April1990 Buses 52 67 119 16 103 Vanpools 24 27 51 24 27 Carpools 1309 1573 2882 990 1892

Total 1385 1667 3052 1030 2022

NOTES: AM Peak Period is 6:00 - 9:30 am. Demand at Silber represents maximum demand between Gessner and Post Oak.

7

Table 2. AM Peak Hour Vehicle Volumes, 1-10 Katy Transitway

Entering West Entering Demand Exiting at Exiting to Time Period of Gessner at Gessner at Silber Post Oak 1-10 EB

January 1990 (6:15-7:15) (6:30-7:30) Buses 24 11 35 1 34 Vanpools 16 6 22 7 15 Carpools 721 313 1034 428 606

Total 761 330 1091 436 655

February 1990 (6:15-7:15) (6:30-7:30) Buses 23 12 35 3 32 Vanpools 16 6 22 9 13 Carpools 761 392 1153 393 760

Total 800 410 1210 405 805

March 1990 (6:15-7:15) (6:30-7:30) Buses 22 16 38 1 37 Vanpools 15 8 23 10 13 Carpools 739 369 1108 401 707

Total 776 393 1169 412 757

April1990 (6:00-7:00) (6:30-7:30) Buses 17 25 42 5 37 Vanpools 17 8 25 8 17 Carpools 727 446 1173 352 821

Total 761 479 1240 365 875

NOTES: Demand at Silber represents maximum transitway demand. Demand entering at Gessner calculated from values on table; travel time differences not considered. (6:15- 7:15) denotes peak hour.

8

which present peak hour totals that are typically based upon maximum hourly passenger

volumes. A separate peak hour was determined for the west of Gessner location; the

peaking characteristics of the two locations (west of Gessner and at Silber) differ because

of travel time. The highest AM peak hour observed in April had an hourly flow of 1,240

vehicles, 479 (34%) of those entered at Gessner. Approximately 30 percent (352 vehicles)

of the carpools were observed to exit the transitway at Post Oak. These volumes are

depicted in Figure 3. Vehicle volumes during the AM peak hour (based on vehicle

demands) are approaching levels experienced prior to the implementation of the 3 + restriction during the peak hour.

Traffic counters were placed at three locations along the transitway to evaluate peak

flow rates. Data collected in 5-minute intervals was multiplied by 12 to obtain equivalent

hourly flow rates. The data presented in this section of this report was collected on

Wednesday, May 23, 1990. During the AM peak period, three critical locations have been

identified for a detailed examination of flow rates: West of Gessner, East of Gessner, and

at Silber (i.e., just west of Post Oak Exit/Eastern Extension merge). Table 3 presents these

hourly flow rates at each location for a typical AM peak period as observed in May 1990.

Figure 4 provides a graphical presentation of this data; time periods of demand exceeding

capacity are indicated at each count location for an assumed LOS C capacity of 1,500

vehicles/hour (~). The impact of the 3 + restriction in reducing the flow rates below

capacity is apparent after 6:45 am. Those observed east of Gessner and at Silber peak later

and for longer duration than that west of Gessner; this is a result of travel time and those

choosing to enter the lane while "cheating" on the restricted period. It should also be noted

that flow rates observed at Silber are lower and occur later during the AM peak period, a

result of travel time and increasing vehicle headways.


Travel time and speed studies were completed on the freeway mainlanes and

transitway in March 1990. The limits of the study were the Western and Eastern Terminus

of the transitway. The results of this study for the AM peak period (by 30-minute

headways) are presented in Table 4. Comparing a similar trip, speeds on the transitway

9

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~~ u u '"-l " ::c: 0 ~ c: CQ z Q. ~A

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OLOKATY~ CQ

5-Buses AD DICKS 8-Vaapools

~ WEST 352-Cat-pools _ PARK ROW P&R BELT

I~ P&R --; .~ fZJ

KATY FREEWAY WB +-- - _l_ :.J~ .~ - ,.-

cp / KATY FREEWAY EB '\ ~ 1-

17-Buses 25-Buses 17 -Vaopools . 8-Vanpools

37-Buses - :t- WAS 727 -Carpools 446-Carpools 42-Buses 17-\Taapools- !-761-Vehicles 479-Vehicles 25-Vaopools 821-Carpools . !-

0 117~s 875-Vebicles u

HINGTON

1240-Vebicles r./) '"-l ~

I'IK>T TO SCALE.

Figure 3. Katy Transitway Eastbound, AM Peak Hour Volumes, April 1990

Table 3. Katy Transitway Eastbound 5-Minute Flow Rates, May 1990

Observed Flow Rate in Vehicles per Hour* Time Interval West of Gessner East of Gessner At Silber

6:00 - 6:05 am 192 348 240 6:05- 6:10 300 576 360 6:10- 6:15 312 576 552 6:15- 6:20 540 780 468 6:20- 6:25 6% 1020 756 6:25- 6:30 684 1212 972 6:30- 6:35 888 1260 1104 6:35- 6:40 1152 1620 960 6:40- 6:45 1332 1848 15% 6:45- 6:50 15% 2076 1428 6:50- 6:55 768 1176 1608 6:55- 7:00 288 552 1656

7:00 - 7:05 am 324 660 600 7:05- 7:10 276 456 660 7:10- 7:15 3% 660 384 7:15- 7:20 360 552 612 7:20- 7:25 264 600 576 7:25- 7:30 336 648 540 7:30- 7:35 300 6% 648 7:35- 7:40 516 912 636 7:40-7:45 360 900 780 7:45- 7:50 252 552 900 7:50- 7:55 336 684 504 7:55- 8:00 312 780 600

8:00 - 8:05 am 252 648 684 8:05- 8:10 312 816 540 8:10- 8:15 336 840 828 8:15- 8:20 444 960 648 8:20- 8:25 708 1380 1008 8:25- 8:30 456 948 1356 8:30- 8:35 324 840 852 8:35- 8:40 372 744 756 8:40- 8:45 192 636 720 8:45- 8:50 204 780 624 8:50- 8:55 204 516 720 8:55- 9:00 204 492 444

*Flow rate = (5-minute data) x 12

11

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2100

1800 -l

!I :::> 0 1500 I

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I H 900 I

I w I 1-- ]:. <( !I I 3: I

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300 -r /w-W

0

600

Figure 4. 1-10 Katy Transitway Flow Rates, Eastbound, AM Peak Period

1-10 KATY TRANSITWAY FLOWRATES EASTBOUND -- AM PEAK PERIOD

I I

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It \ ASSUMED CAPACITY=1500 vph I

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700 BOO

TIME OF DAY -- AM PEAK PERIOD

NOTES: FLOWRATE= (5-Minute Data) * 12 W = West of Gessner; E = East of Gessner; S Data for Wednesday, May 23, 1990

At Silber

~ 'w-w--w-w

900

Table 4. Results of Travel Time Studies, AM Peak Period, March 1990

Enter Transitway at Gessner1 Enter Transitway at Western Terminus2

Start Time Transitwa~ Trin Freewa~ Trin Transitwa~ Trin Freewa~ Trin (minutes) (mph) (minutes) (mph) (minutes) (mph) (minutes) (mph)

6:00am 6.85 49.5 5.55 61.1 14.53 52.0 13.10 57.7 6:30am 5.22 64.9 7.08 47.9 12.55 60.2 18.73 40.4 7:00am 6.57 51.6 9.27 36.6 14.28 52.9 21.57 35.0 7:30am 6.08 55.8 11.53 29.4 13.40 56.4 22.60 33.5 8:00am 6.15 55.1 9.05 37.5 13.62 55.5 18.23 41.5 8:30am 5.67 59.8 6.00 56.5 12.42 60.9 13.10 57.7 9:00am 6.15 55.1 5.70 59.5 13.23 57.1 12.42 60.9 9:30am 5.65 60.0 5.87 57.8 12.42 60.9 12.87 58.7

Average 6.04 56.1 7.51 45.1 13.31 56.8 16.58 45.6

1 Trip Length = 5.65 miles 2 Trip Length = 12.60 miles

averaged 56 mph compared with 45 mph on the freeway mainlanes for the entire peak

period. Maximum savings of almost 10-minutes per trip was realized for a trip along the

transitway from the Western to Eastern Terminus. A plot of transitway and freeway

running speeds along this route is presented by Figure 5. With the exceptions of the fringes

of the peak period, transitway users receive travel time savings compared to a similar trip

on the freeway mainlanes. Time differentials at the fringes are minimal and may be

incurred at access points along the lane. Average running speeds on the transitway are

greater than 50 mph throughout the peak period.

Speed studies were also completed using automatic traffic counters at three locations.

This equipment will estimate the speed of a vehicle and record it within a specified 5-mph

range. Although speeds of individual vehicles are not recorded, the data (collected in IS

minute intervals) can be used to identify specific operational characteristics of the

transitway. The results of this analysis for the AM peak period are presented in Table 5.

This data was collected in early April during weekday operations. Consider that the

counting equipment may not have recorded the speed of every vehicle, however, the sample

results provide insight as to transitway performance during inbound operations. The sample

study of speeds east of the Gessner slip ramps indicate speeds averaging 40 mph during

the AM peak period. This is a result of the merging operation of vehicle entering at

Gessner and the reduced speed of the vehicles east of the slip ramps prior to accelerating

13

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D w w n.. UJ

(.!)

z H

'"""' z

~ z ::::> a: w (.!) <{ a: w > <{

T

65

60

55

50 ' ' ' ' ' 45 ' ' ' ' 40

35

30

25

20

15

10

5

0 'T

600

Figure 5. 1-10 Katy Freeway/Transitway Average Speeds, Eastbound, AM Peak Period

I-10 KATY FREEWAY/TRANSITWAY AVERAGE SPEEDS EASTBOUND -- AM PEAK PERIOD

)::._

.... .... r---------p

700

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

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

/ /

.... P"

BOO

/ /

/ /

/ /

/ /

/

/

/ /

/

F--

TIME OF DAY -- AM PEAK PERIOD

900

Transi tway Speed: F Freeway Speed

1000

Table 5. AM Peak Period Sample Speed Study Results

East of Gessner Silber Eastern Extension Time #Vehicles Avg Speed #Vehicles AvgSpeed #Vehicles Avg Speed

6:00 - 6:15 am 31 43.8 13 57.5 14 54.3 6:15- 6:30 88 42.6 51 58.1 24 57.5 6:30- 6:45 199 40.8 103 54.6 66 55.7 6:45- 7:00 340 40.2 187 50.9 95 53.9

7:00 - 7:15 am 335 33.4 242 49.6 141 53.6 7:15- 7:30 118 40.3 120 53.7 58 56.5 7:30- 7:45 147 38.5 87 54.9 55 55.1 7:45- 8:00 155 39.1 106 54.5 51 54.3

8:00- 8:15am 156 40.1 % 51.9 54 53.7 8:15- 8:30 144 40.2 84 54.4 51 54.2 8:30- 8:45 245 40.7 158 54.4 107 55.7 8:45- 9:00 192 40.8 140 53.6 89 55.6

NOTE: #Vehicles represents sample size for average speed determination; actual transitway flow rates may be higher.

to free-flow speed. Speeds at Silber and on the Eastern Extension are generally in excess

of 50 mph, indicating no major slowdowns as vehicles approach the merge.

Capacity Analysis

Level of service (LOS) on the transitway is estimated using the Highway Capacity

Manual (5.). The analyses used volume data collected during the first months of operations

upon completion of the Eastern Extension. The first analysis considers the transitway as

a one-lane freeway and estimates the LOS at the maximum loading point east of the

Gessner slip ramp. The LOS is based upon the observed transitway volume and criteria

included in Table 3-1 of the HCM. Please note that the volumes vary on a daily basis; the

maximum observed demands are presented. Previous studies (1) have assumed a transitway

LOS C capacity of 1,500 vph. Table 6 presents the transitway LOS as calculated by both

methods. Considering these values which represent the highest hour observed, the facility

presently operates at a LOS B-C range using HCM procedures compared with LOS C-D

using a capacity of 1,500 vph/lane.

15

Table 6. Basic Section Level-of-Service, AM Peak Hour

Maximum Peak Start Date No. of Days Hour Demand

1-08-90 5 996 1-15-90 1 800 2-16-90 1 1211 2-19-90 1 822 4-06-90 3 1092 4-10-90 3 1007 5-01-90 4 1190 5-14-90 4 1076 5-22-90 4 1205

1 Based upon maximum capacity assumed at 2,000 vph/lane. 2 Based upon maximum capacity assumed at 1,500 vph/lane.

HCM Method1

'l.}s, LOS

0.50 B 0.40 B 0.61 c 0.41 B 0.54 B 0.50 B 0.60 c 0.54 B 0.60 c

Assumed Capacity2

'l.}s, LOS

0.66 c 0.53 B 0.81 D 0.55 c 0.73 c 0.67 c 0.79 D 0.72 c 0.80 D

If the maximum 5-minute flow rates of Table 3 are used, the capacity analysis

provides results of much greater concern. The peak 15-minutes during the AM peak hour

resulted in an average flow rate of approximately 1,750 vph. Using HCM procedures, this

results in a volume-to-capacity ratio of 0.88 and LOS D operations. Flow rates within the

1,500 - 1,850 vph range are observed prior to implementation of the 3 + restriction.

Because of lower volumes during the restricted period, total traffic demands result in the

peak hour LOS as reported. If the restriction were not to be implemented during the AM

peak period, congestion could once again develop on the lane.

If the transitway was assumed to be a freeway section with a one-lane ramp entering

at Gessner, a capacity analysis of the AM peak hour ramp merge can also be completed.

Considering the transitway demands of April 1990 as presented by Figure 3, a merge

volume of 1,240 vph results in LOS C operations. Although this is 8 to 15 percent less than

that observed in 1987 (1), the LOS of the merge has remained unchanged.

Several studies have been completed by TTl on the operations at the Post Oak

terminus of the Katy Transitway. Turning movement studies were completed in October

1989, January 1990, and March 1990. Using the results of the turning movement studies,

the most efficient signal phasing (for each hour) at the intersection was determined using

the TRANSYT-7F signal optimization model. To simplify this effort, simple 4-phase signal

timing without overlaps was assumed for the analysis. The program was allowed to select

16

the appropriate cycle length resulting in the least amount of total intersection delay. These

results for the 6:00 - 9:00 am peak period are presented in Table 7. Comparing the

October 1989 and March 1990 results, intersection operations in terms of LOS are identical.

However, the removal of approximately 800 vehicles during the AM peak period has

reduced total intersection delay by 24 percent. Overall intersection operations have

improved since the Eastern Extension of the transitway opened in January. Addition of a

right-turn lane for North Post Oak northbound would provide additional delay reductions.

Table 7. Summary of AM Peak Period Operations, Katy Transitway Post Oak Terminus

AimroachLMonth Total Volume Total Delay Average Delay LOS (veh/hr) (veh-hrs) (secjveh)

Transitway (EB) Approach October 1989 1728 14.13 29.4 c January 1990 852 6.29 26.6 c March 1990 879 5.23 21.4 c

All Approaches October 1989 7040 56.75 29.0 c January 1990 7089 54.76 27.8 c March 1990 6214 43.37 25.1 c

NOTE: Values reported represent entire 6:00- 9:00am peak period.

Summacy of AM Peak Period Operations

Based upon the analyses presented in this report, the Katy Transitway is operating

at an "acceptable" level of service during the AM peak period. In most cases, this equates

to LOS C operations. There should, however, be some concern about operations in the

transitway section east of Gessner. Since the Eastern Extension became operational, total

transitway peak hour vehicle demand has increased by 14 percent to 1,240 vph. Demands

west of Gessner have remained constant while the Gessner entrance increased from 330 vph

to 479 vph (January- April); this represents a 45 percent increase. It can be concluded that

many motorists previously did not use the lane (east of Gessner) because of the portion of

the trip along Old Katy Road. These "new" users are attracted to the transitway because

of the additional travel time savings using the Eastern Extension compared with the

previous surface street route.

17

As indicated by Table 3 and Figure 4, flow rates exceeding 1,500 vph exist prior to

implementation of the 3 + restriction at 6:45 am. This condition occurs only for a 15-20

minute period as 2+ carpoolers "rush to get on the lane" before (and sometimes after) the

restricted period. Since vehicle demand is significantly reduced during the restricted period,

queueing does not occur on the transitway. Platoons of tightly spaced vehicles have been

observed near egress points along the lane; however, vehicle headways usually increase as

each begins to accelerate to 55 mph. The delays incurred in this manner are negligible

compared to the overall travel time savings; these delays are synonymous with those

incurred when entering a freeway.

In summary, the transitway operates at an acceptable level of service with the

existing occupancy requirements (3+ between 6:45- 8:15am; 2+ other times). However,

increases in transitway demand of 10 to 20 percent during the AM peak hour could

significantly impact operations resulting in conditions comparable to those prior to

implementation of the restriction. Modifications to the existing restrictive periods and/ or

other innovative measures to manage demand may be necessary in the future if vehicle

demands continue to increase.

18

OPTIONS FOR MANAGING DEMAND DURING THE AM PEAK PERIOD

In a previous report (.1), TTI examined alternatives to manage demand during the

AM peak period. After reviewing the possible impacts of these options, METRO/SDHPT

implemented a 3 + requirement between 6:45 - 8:15 am. The continuance of this

requirement and other options will be examined in detail. The alternative demand

management actions to be considered for the AM peak period include:

1. Voluntary spreading of peak-hour demand;

2. Imposing a 3 + carpool definition during the peak hour;

3. Requiring authorization during the peak hour; and

4. Closing and/or metering entrance ramps during the peak hour.

Voluntary Spreadina= of Peak Hour Demand

Since the transitway does experience sharp peaking, if a relatively small percentage

of the traffic using the transitway could be encouraged to alter its trip time in order to not

be on the transitway during the peak hour, the congestion problem could be "solved." In

an attempt to shift transitway demand, METRO, in September 1987, sent carpoolers a post

card requesting users to adjust their travel. This voluntary effort was unsuccessful in

reducing peak hour demand, and it appears that the motorists in Houston were unwilling

or unable to adjust their work trip travel to accommodate such a request. A mandatory

demand management technique was then implemented in October 1988.

Imposina= a 3 + Carpool Definition durin&: the Peak Hour

The occupancy requirement to use the transitway can be adjusted to reduce vehicular

volume during the peak hour. This alternative was implemented on the Katy Transitway

in October 1988. The 3+ requirement, imposed between 6:45 - 8:15 am, has been

successful in reducing congestion on the lane during the peak hour. The unique design

(barrier separated transitways with a limited number of access/ egress locations) and regular,

routine enforcement associated with the transitway greatly enhanced the feasibility of this

demand management approach. Data available through December 1989 examining the

19

impacts of this alternative are presented for informational purposes in Table 8. Detailed

evaluation of the impact of this demand management alternative is beyond the scope of this

report, however, possible impacts should the 3 + requirement be removed are examined.

Table 8. AM Travel Volumes Before and After Change in Occupancy Requirements, Katy Freeway Corridor

"Representative" Value After Occupancy Change Pre-Occupanc~ 11/~8 and 12/88 03/89 12/89

Travel Volumes Change Value Value % Change3 Value % Change3 Value % Change3

Daily Transitway Person Volume 18,880 16,595 -12% 17,831 - 6% 18,352 -3% AM Peak-Period Person Volume, Total 8,780 7,265 -17% 7,945 -10% 7,523 -14%

2 Person Carpools 5,090 2,490 -51% 2,800 -45% 2,998 -41% 3 + Person Carpools 935 1,835 + 96% 1,905 +104% 1,569 +68% Total, Carpool Riders 6,025 4,325 -28% 4,705 -22% 4,567 -24% Bus Patrons 2,450 2,670 + 9% 2,885 + 18% 2,645 + 8% Vanpool Riders 305 270 -11% 335 + 16% 311 + 2%

7:00-8:00 am, Total Person Volume 4,320 2,915 -33% 3,445 -19% 3,079 -28%

Carpools 2,885 1,315 -54% 1,705 -39% 1,557 -46% 2 Person Carpools 2,410 230 -90% 480 -80% 670 -72% Bus Patrons 1,310 1,500 + 15% 1,490 + 14% 1,415 + 8% Vanpoolers 125 100 -20% 205 + 64% 107 -14%

AM Peak Period Vehicle Volume, Total 2,900 1,950 -33% 2,120 -27% 2,155 -26%

Carpools 2,780 1,820 -34% 1,990 -28% 1,971 -29%

7:00-8:00 am, Total Vehicle Volume 1,400 510 -64% 730 -48% 688 -51%

2 + Carpool Vehicles 1,365 455 -67% 660 -52% 611 -55% 2 Person Carpools 1,205 115 -90% 240 -80% 335 -72% 3+ Carpools 160 340 +112% 420 +162% 276 +72%

Carpool Vehicle Volume (6:00-7:00 and 8:15-9:30) 1,230 1,170 - 5% 1,295 + 5% 1,360 +11%

Freeway Mainlane Volumes, 6:00-9:30am

Vehicles 15,300 15,900 + 4% 16,805 + 10% 19,367 +27% Total Persons 16,455 17,230 + 5% 18,675 + 13% 20,432 +24% Average Vehicle Occupancy 1.075 1.084 + 1% 1.111 + 3% 1.055 -2%

1 This is the value representative of the trend line that existed prior to changing the occupancy requirement. It does not reflect the values for any particular month.

2 These are representative of the average of the November and December 1988 data. 3 The percent change in comparison to the representative pre-occupancy change value.

Source: Reference (~.

20

The most basic reason for not reinstating a 2 + requirement is that -- disregarding

the fact that transitway demand is estimated to increase at 2 to 3 percent per year-- today's

transitway demand with a 2+ requirement exceeds the transitway capacity. The same

conditions that existed in the Fall of 1988 that led to the 3 + decision would reoccur. Prior

to opening the Eastern Extension of the transitway, constraints on the AM capacity of the

Katy Transitway included: 1) the merge at an AM slip ramp from the inside freeway lane

to the transitway in the vicinity at Bunker Hill; 2) the horizontal and vertical curvature on

the structure approaching the Post Oak terminus of the transitway; and 3) the Post Oak

terminus of the transitway ending at a signalized intersection. The opening of the Eastern

Extension addressed only two of these controlling factors by removing approximately 60

percent of the transitway vehicle demand out of the Post Oak terminus.

During the time period when a 2 + requirement existed during both the AM and PM

peak hours, AM volumes were consistently 10 to 15 percent greater than PM volumes.

Since the Eastern Extension opened, PM peak-hour volumes frequently exceed 1,600 vph

and are resulting in delay problems. It is reasonable to assume that AM demands would

be at least this great and possibly 10 to 15 percent greater. It is generally accepted that

1,400 vph to 1,500 vph represents the "capacity" of a transitway. Because of the high

volume merge that occurs at Gessner, 1,200 vph to 1,400 vph probably represents the

desirable capacity of the section from Gessner to Post Oak. Quite simply, a 2 + requirement will exceed the capacity of the transitway. A major intent of the transitway will

cease to exist.

The high peak-hour volumes that would result with a reinstatement of 2+ occupancy

requirement would increase the number of breakdowns experienced on the transitway. This

may have the effect of reducing the travel time reliability offered by the transitway; an

attribute that is very important to the success of the transitways. Similarly, as volumes on

the transitway increase, concern over the safety of operations increases. At 1,800 vph, the

lane would operate at an average 2 second headway between vehicles. When the

transitways first opened, an operational guideline of 3 second headways, or 1,200 vph, was

recommended.

21

It is expected that, in the design year, the Houston transitways will move 7,000 to

10,000 persons per hour per lane. This design volume has been used in justifying the lanes

and in planning how future freeway demands will be handled. This design volume simply

will not be attained with a 2 + carpool requirement. With the 2 + requirement, the Katy

Transitway, operating at vehicular capacity, moved about 4,500 persons in the peak hour.

Thus, there has always been an implicit assumption that, at some date, a 3 + requirement

would be applied on the transitways at least during the peak hour to attain the design year

volumes. With a 3 + carpool requirement, the transitways are expected to move 4,200

persons per hour in buses (85 buses at 50 persons per bus) and 3,800 persons per hour in

carpools (1,200 vehicles at 3.2 persons per vehicle). Experience on other HOV lanes also

suggests that a 7,000 to 10,000 hourly person volume will not be attained unless at least a

3 + occupancy requirement is in effect.

Public comments have been received by METRO requesting removal of the 3 + requirement during the peak hour. It is perceived that since the Eastern Extension opened

in January 1990, all capacity problems on the lane have been solved. Although the traffic

signal at the Post Oak terminus was a problem, the capacity of the transitway would have

been exceeded even without the signal.

To address the complaints currently being received as a result of the 3 + requirement, one option is to reduce the length of the restricted period. The initial intent

of the restriction was to assure free-flow on the transitway between 7:00 and 8:00 am.

During the 15-minute transition periods before and after this hour, higher than usual

violation rates were expected and observed. At present, volumes prior to 6:45 am are

relatively high, and moving the restricted time from 6:45 to 7:00 does not appear

appropriate. This time period is also critical so that vehicles legally entering the transitway

prior to 6:45 am are able to clear the transitway by 7:00 am. However, a review of recent

volume data suggests that transitway demand begins to drop after 7:45 am. Thus, there

would be no strong technical argument against ending the restricted period at 8:00 am

instead of 8:15 am. This is particularly true if adequate enforcement is provided and/or

if innovative enforcement techniques are found to be feasible and effective. Careful

monitoring of demands and violation rates should be continued as the 3 + violators begin

to "cheat" on the 8:00 am time period.

22

Require Authorization durin~: the Peak Hour

The authorization concept would be reintroduced. Carpools using the transitway

during the peak hour would have to display a permit (possibly a permit that hangs from the

rear view mirror). With appropriate use of enforcement and the surveillance,

communications, and control system, implementation of this alternative appears feasible.

Previous Til research (Table 9) has estimated the imposing authorization on

transitway demand would reduce the demand by 40 percent. This estimate may be

somewhat high in that the authorization procedure used was more stringent than would be

employed were this concept reintroduced. However, since the operating agencies have

control over the number of authorization permits issued, they can, in effect, be assured that

an acceptable demand reduction is achieved through this approach.

Since the 40 percent estimate may be high with a less stringent authorization

procedure, a range of 20 percent to 40 percent is assumed to be representative of the

demand reduction implications of authorization. This approach appears viable and should

be considered for possible implementation, since it could also be used during the PM peak

period. However, there are problems with this technique:

1. Adequately informing the public of the strategy will be difficult. In addition

to other means of notifying the public, adequate signing will need to be

provided to inform motorists of the requirements for using the transitway;

2. METRO will need to develop procedures and to commit resources for

authorizing large volumes of vehicles;

3. Strict enforcement will be required; and

4. Since all demand management strategies are intended to adversely impact

some current users of the transitway and since some confusion will exist over

peak-hour only authorization, adverse public reaction may be generated.

23

Table 9. Estimated Factors for Converting Unauthorized Carpool Demand to Authorized Carpool Demand

Data Source

Katy Transitway, Houston (Change from Authorized to Unauthorized in August 1986) 1

3+ Volume during Authorization (12/85 - 5/86) = 187 /day 3+ Volume without Authorization (9/86- 2/87) = 428/day

Katy Transitway Carpool Survey (10/86)

Response to question, "If it were still necessary to be issued a permit by METRO to be authorized to use the transitway, would you be using the transitway?" Yes = 55%; No = 23%; Not Sure = 22%

Response to question, "If METRO finds it necessary to issue permits to maintain free flow, would you be willing to get a permit?"

Katy Transitway Carpool Survey (4/87)

Response to question, "If you carpooled prior to August 1986 but did not use the transitway, why did you choose to not use the transitway (responses from 3+ carpools)?" 58% Authorized process was too cumbersome; 48% Other

Range of Values

Average Value

Suggested Value for Houston Planning

Authorized as a Percent of Unauthorized

44%

66%

76%

62%

44% to 76%

62%

60%

1 At the time authorization was eliminated, the eligible carpool definition was also reduced from 3 + to 2 +.

Source: Reference (Q).

If this option is to be implemented, it is recommended that the authorization process

be required for using the Katy Transitway during the entire AM peak period (6:00- 9:00

am), thus capturing the majority of work trips. However, the authorization (or registration)

process should be refined from that previously used. The previous method required

carpoolers to take a driving test and have the vehicle routinely inspected. That portion of

the authorization process should be discontinued. A possible authorization process could

be based on some of the items listed below.

1. Potential users would be required to register as a "carpool group." Each

carpool would be required to complete a form, with each person filling out

24

a portion of the same form. Standard questions could include name, home

address, point of carpool formation, work destination, and time and point of

transitway access. To assure validity of the application, it may be necessary

to contact a random sample of applicants.

2. After receipt of all applications, METRO could issue permits to users of the

transitway based upon their time and place of lane entrance and usual carpool

occupancy. This provides for a demand management technique allowing for

the highest vehicle occupancy. A priority pyramid could be established to

assist in deciding which carpools would receive a permit.

a. The total transitway demand should be kept at an acceptable level

below capacity to assure free-flow conditions. To maintain 3 second

headways, this demand should be less than 1,200 vehicles/hour east of

the Gessner access.

b. First priority must be given to buses and participants in the vanpooling

program. All types of buses should be allowed on the lane including

intercity and school buses. Since all buses and most vanpools adhere

to some type of schedule, their time and point of transitway entrance

is usually constant.

c. After all buses and vanpools within a specified time period are allowed,

carpools are authorized to use the lane with a priority to those with

the highest occupancy. This would provide for some 2+ carpools on

the lane; even during the peak hour. Since not all 2+ carpools who

apply for registration would be allowed on the transitway because of

capacity restraints, another selection process must be used. The first

group logically to be rejected are 2+ carpools with an adult and a

small child. A second group could include married couples that do not

work at the same or close-by locations. These groups are not "real car

pools" and most likely would never increase occupancy above 2-persons.

This indicates that a long-term goal of modifying the definition of a

carpool may be necessary to manage demand.

3. Since this process is based upon a time/occupancy/capacity restraint,

enforcement could be a major problem. A routine sampling of users could

be implemented. The sampling process could involve stopping random

25

vehicles, recording their authorization number and number of occupants. The

time on the lane and occupancy level could later be checked against their

application on file. This information could be used to warn users (with a

letter or post card) if the occupancy requirement is not met. It is probably

more difficult to comment on their time of use of the lane. Although the

majority of users would enter the transitway within the time period stated on

the application, this should not be included in any type of METRO response.

This information, however, should be kept available as users reapply for the

permit upon its expiration.

It is probably not possible to impose a monetary fine on users that do not meet the

occupancy and time of lane use information as indicated on their application. However,

proper signing could be designed to allow ticketing of those violating a minimum 2 + requirement and/ or those without authorization during the restricted period. How this

would be received in the court system must be investigated before this strategy would be

implemented and should be a factor considered in the decision process.

In many ways this possible authorization process is simpler than the previous method,

although other difficulties have been introduced. A personal computer could be used to

determine which users should be authorized to use the lane. "Border-line" cases could be

evaluated by reviewing the application and personal contact by telephone. Although this

authorization process is complicated, it does allow for a mix of buses, vanpools, and

carpools (at the highest occupancy level) on the transitway while maintaining a near

capacity vehicular volume.

Close and/or Meter Entrance Ramps during the AM Peak Hour

A final option involves reducing access to the transitway for all or part of the peak

hour by either closing ramps or metering ramp volumes. Since the transitway essentially

operates as a one-lane freeway, ramp control, which has successfully controlled freeway

operations for several years, should be seriously considered. Geometries at each of the AM

access points do cause specific problems. Generic problems that will be experienced at all

locations are listed below.

26

1. Adequately informing the public of the strategy will be difficult. Again,

adequate signing will need to be provided;

2. All access points must remain accessible to buses and vanpools. Enforcement

of carpools using a ramp that does not allow carpool access will be difficult;

3. Extreme opposition can be expected from current users of any ramp to which

control strategies are applied; and

4. If any strategy is implemented at either the western or intermediate access

is affected, discrimination against longer or shorter trips does occur.

Additional problems will occur at each ramp because of geometries, and each ramp should

be evaluated on an individual basis. Operational plans for each strategy should be

developed prior to implementation of any ramp metering or closure. Possible problems at

each access point for the eastbound direction are discussed below.

Metering of the Western Terminus slip ramp is not recommended because of high

speed freeway operation and the lack of storage space for queued vehicles. Restricting

access to buses and vanpools is possible, however, enforcement problems anse. An

enforcement strategy could be developed in which the officer is stationed in the PM exit

(facing eastbound) to discourage possible carpool users from entering the transitway. Any

violators could then be followed by the enforcement vehicle and directed to exit at the

Addicks Park-and-Ride lot. Restricting access only at the Western Terminus would not

prevent carpools from entering at the park-and-ride or at Gessner.

Access restrictions at the Addicks Park-and-Ride lot have a similar problem in that

restricted vehicles could enter the lane at Gessner. Completion of the Addicks South Ramp

would complicate matters by requiring demand management at two access points. If ramp

meter signals were to be used at either the North or South Ramp, provisions are necessary

to store queued vehicles. Considering the existing North Ramp, Park Row Street could be

used to store the vehicles. However, should the street be extended eastward to intersect

with Eldridge Parkway, storage on the street could not be safely implemented. Buses

accessing the park-and-ride to pickup passengers could also be hindered while accessing the

loading area. Total closure of the access to carpools is easily done because of geometries.

27

However, provisions are necessary for vanpools to be allowed access through the bus

loading area to enter the transitway.

A total closure of the Gessner slip ramp is not recommended because of the high

volume of bus patrons entering the facility at that location. Restricting access to buses and

vanpools is possible, but enforcement is a problem. A similar strategy as explored for

Western Terminus access could be implemented using the westbound slip ramp exit.

Because of lack of safe storage for any queued vehicles, the use of ramp meter signals is

not practical. High speed operations along the freeway mainlanes could also cause

problems for those unsure of access at the slip ramp. Although traffic congestion does exist

in the freeway section adjacent to the slip ramp, vehicle speeds in the area are sporadic,

ranging from stop-and-go to free-flow speeds.

If any type of metering or ramp closure is implemented, the use of the changeable

message signs must be expanded to aid in informing motorists. A detailed analysis of

potential impacts on bus operations and vanpool programs should be completed prior to

implementation. Public reaction from such action should also be considered.

Recommendations

Based on the current operations of the Katy Transitway during the AM peak period,

the following options for controlling demand are recommended:

1. Retain the current 3+ carpool requirement from 6:45am to 8:15am. Based

on current volumes being observed on the transitway, if, for other purposes

such as public acceptance, it is felt that ending the restricted period at 8:00

am instead of 8:15 am is desirable, there would be no strong technical

argument against such an action. However, it is recommended that the

restricted period should begin no later than 6:45 am and end no earlier than

8:00am;

2. Consider implementing the authorization process based upon a time/

occupancy/ capacity restraint. This option for managing demand should be

seriously considered if vehicle demand on the transitway continues to increase.

28

Although this option requires additional cost and effort by METRO to

implement and monitor, it does allow for maximum use of the transitway by

buses, vanpools, and carpools at all occupancy levels while maintaining a high

level-of-service; and

3. Assure that sufficient resources are made available to the METRO Transit

Police so that adequate personnel and equipment can be assigned to the

transitway to enforce the operating guidelines. Innovative enforcement

techniques and greater support by the traffic courts should be pursued.

Negative reaction from the public should be expected, especially if any type of access

IS restricted. Therefore, the selection of any demand management strategy must be

carefully considered. The intent of the transitway of providing high speed travel and

reliable travel time and its appearance of being adequately utilized must be maintained.

29

PM PERIOD OPERATING CONDITIONS

The transitway presently operates in the westbound direction from 2:00pm to 10:00

pm during normal workdays. The HOV lane is used by buses, vanpools, and 2+ person

carpools. Since the 1.5 mile Eastern Extension became operational in January, concerns

have been expressed about the merge operation near Silber. Traffic congestion has been

observed in this area, particularly on Friday afternoons.

Vehicle Demands

TTl collects vehicle and passenger data at three locations along the Katy Transitway:

Eastern Extension, at the Post Oak Terminus, and East of Addicks. Although the data is

collected only one day each month, the values reported are representative of typical

operations for normal non-incident conditions on the HOV lane. Table 10 presents

transitway demands as observed during the PM peak period (3:30 - 7:00pm) since the

Eastern Extension opened. Total transitway demand has increased by approximately 22

percent since January. About 60 percent of the users are entering the lane via the Eastern

Extension. Vehicle demands entering via the Post Oak entrance have not significantly

changed since the initial operation of the Eastern Extension. Peak period demands for

those using the transitway west of Gessner have not yet stabilized; these may not have

significantly changed. However, the demands for the Gessner slip ramp have increased

from 1,199 to 1,990 vehicles during the peak period, an increase of 66 percent. This

additional approximate 800 vehicles are most likely the same vehicles that were attracted

to the HOV lane during the AM peak period.

Table 11 presents similar data for the PM peak hour. The determination of the

peak hour was based upon the maximum vehicle demand at Silber. This was estimated by

summing 15-minute data from the Post Oak and Eastern Extension count locations; the

maximum hourly flow is reported. This should not be confused with other TTl reports

which are typically based upon maximum hourly passenger volumes. A separate peak hour

was determined for the west of Gessner location; the peaking characteristics of the two

locations (west of Gessner and at Silber) differ because of travel time. The highest PM

peak hour observed in March 1990 had an hourly flow of 1,713 vehicles, 879 (51%) of those

30

Table 10. PM Peak Period Vehicle Volumes, 1-10 Katy Transitway

Entering at Entering Demand Exiting Exiting West Time Period Eastern Extension at Post Oak at Silber at Gessner of Gessner

January 1990 Buses 71 4 75 32 43 Vanpools 28 18 46 29 17 Carpools 1413 1533 2946 1138 1808

Total 1512 1555 3067 1199 1868 February 1990

Buses 66 7 73 27 46 Vanpools 25 17 42 17 25 Carpools 2200 1342 3542 1896 1646

Total 2291 1366 3657 1940 1717 March 1990


Total 2388 1360 3748 1822 1926 April1990


Total 2262 1467 3729 1990 1739

NOTES: PM Peak Period is 3:30 - 7:00 pm. Demand at Silber represents maximum demand between Post Oak and Gessner.

31

Table 11. PM Peak Hour Vehicle Volumes, 1-10 Katy Transitway

Entering at Entering Demand Exiting Exiting West Time Period Eastern Extension at Post Oak at Silber at Gessner of Gessner

January 1990 (5:00-6:00) (5:30-6:30) Buses 30 2 32 11 21 Vanpools 6 2 8 6 2 Carpools 565 595 1160 327 833

Total 601 599 1200 344 856 February 1990 (5:15-6:15) (5:15-6:15)


Total 1113 517 1630 898 732 March 1990 (5:00-6:00) (5:15-6:15)


Total 1178 535 1713 879 834 April1990 (5:00-6:00) (5:15-6:15)


Total 950 548 1498 744 754

NOTES: Demand at Silber represents maximum transitway demand. Demand entering at Gessner calculated from values on table; travel time differences not considered. (5:00 - 6:00) denotes peak hour.

32

exited at Gessner. Considering the data collected in April, the PM peak hour was 1,498

vehicles/hour with approximately 50 percent (744 vehicles) of the vehicles exiting at

Gessner. Comparing the AM and PM peak hours, the PM hour has a higher total demand

as well as a higher percentage of vehicle exiting at Gessner. The PM peak hour volumes

observed in April 1990 are depicted in Figure 6.

Traffic counters were placed at three locations along the transitway to evaluate peak

flow rates during the PM peak period. Data collected in 5-minute intervals was multiplied

by 12 to obtain equivalent hourly flow rates. Table 12 presents these values as observed

on Wednesday, May 23, 1990. Figure 7 provides a graphical presentation of this data; time

periods of demand exceeding capacity at Silber and east of Gessner are indicated for an

assumed LOS C capacity of 1,500 vehicles/hour (1.). This indicates a possible problem on

the transitway of demand exceeding capacity for an extended period during the PM peak

period.

It has been observed that this potential problem becomes much more severe on

Friday afternoons. To examine this in detail, the results of traffic studies completed on two

Fridays are presented. Field observations have indicated that the merge between the

Eastern Extension and the Post Oak terminus is the most critical location; therefore the

traffic volumes observed at the Silber location are used for comparison. The two Fridays

selected are: May 18 (a "normal" Friday) and May 25 (a "worst case" Friday; Monday, May

28 was the Memorial Day holiday). Field observations of the transitway were not

completed on May 18, therefore, actual lane conditions are not known. However, sporadic

flow rates most likely indicate that the transitway did experience stop-and-go conditions

during a large portion of the PM peak period. Observations made by Til staff on Friday,

May 25 include:

o Queued traffic on the Eastern Extension between approximately 4:30 - 6:30

pm;

o Freeway section appeared to move faster than the transitway between Post

Oak and the transitway merge point; (Freeway queue cleared before that

observed on the transitway.)

o Pickup pulling boat observed on lane (slide taken by Til personnel);

33

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539-Carpools AD DICKS WEST 25-Buses 548-Vehicla'

~ PARK ROW P&R BELT 4-Vanpools OLD KATY RD

I~ P&R 715-Carpools - t KATY FREEWAY WB - ~ FZJ 744-Vebicles -

.... +-- - I

=~ ~ -KATY FREEWAY EB 1-

"" -+

~ .j::o. 28-Buses 53-Buses 50-Buses 1-

~r :j:: WAS 6-Vanpools 10-Vanpools 4-Vanpools - -720-Carpools 1435-Carpools 896-Carpools

754-Vehicles 1498-Vehicles 950-Vehicles

HINGTON

IIJ ~

NOT 10 SCALE.

Figure 6. Katy Transitway Westbound, PM Peak Hour Volumes, April 1990

Table 12. Katy Transitway Westbound 5-Minute Flow Rates, May 1990

Observed Flow Rate in Vehicles/Hour* Time Interval At Silb~:;r East of Gessner West of Gessner

4:00 - 4:05 pm 948 672 288 4:05- 4:10 1044 1164 576 4:10- 4:15 984 936 480 4:15- 4:20 960 1140 624 4:20- 4:25 996 900 504 4:25- 4:30 984 1044 516 4:30- 4:35 924 972 468 4:35- 4:40 1224 1056 528 4:40- 4:45 1152 1248 648 4:45- 4:50 1296 1164 564 4:50- 4:55 1416 1248 732 4:55- 5:00 1320 1548 708

5:00 - 5:05 pm 1440 1356 768 5:05- 5:10 1572 1404 540 5:10- 5:15 1716 1560 744 5:15- 5:20 1656 1524 900 5:20- 5:25 1500 1656 996 5:25- 5:30 1500 1608 900 5:30- 5:35 1572 1500 768 5:35- 5:40 1596 1584 924 5:40- 5:45 1428 1584 828 5:45- 5:50 1284 1728 888 5:50- 5:55 1476 1212 648 5:55- 6:00 1464 1320 672

6:00 - 6:05 pm 1332 1536 588 6:05- 6:10 1320 1596 732 6:10- 6:15 948 1284 720 6:15- 6:20 936 912 420 6:20- 6:25 804 1008 516 6:25- 6:30 816 804 456 6:30- 6:35 468 732 372 6:35- 6:40 648 576 324 6:40- 6:45 552 624 264 6:45- 6:50 576 564 204 6:50- 6:55 252 588 252 6:55- 7:00 372 252 120

*Flow rate = (5-minute data) x 12

35

w 0'\

2100

1800

Figure 7. 1-10 Katy Transitway Flow Rates, Westbound, PM Peak Period I-10 KATY TRANSITWAY FLOWRATES

WESTBOUND -- PM PEAK PERIOD

II :::) 0 1500

~~, ASSUMED CAPACITY=1500 vph I ......... (f) w _j

u H I w > z H

w I-<( II 3: 0 _j

LL

1200

)N..

\ \ \ \

[

900

600

/v{ w "" . 'f'../''-_~w._lw--/\ l \/ Y\ 'II w -W. ;w-w..,

'w \

300

0

1600 1700 1800

TIME OF DAY -- PM PEAK PERIOD

NOTES: FLOWRATE= (5-Minute Data) * 12 W = West of Gessner; E = East of Gessner; S Data for Wednesday, May 23, 1990

At Silber

v~w.... w... w...

w...W" \

[

'w

1900

o Motor home observed on lane (slide taken by TI1 personnel); and

o A vehicle on the Eastern Extension of the transitway was observed to take

approximately 2 minutes to travel the short distance between the Post Oak

overpass and the merge within the transitway.

In order to determine if there are any differences between a weekday, a "normal",

and a "worst case" Friday PM peak period, a comparison of the flow rates observed at

Silber was prepared. Table 13 presents usual weekday flow rates as compared to that

observed on the two Fridays. These values are depicted graphically in Figure 8. Flow rates

are observed to be higher in an earlier portion of the peak period on Fridays than

compared to a normal weekday. In a similar manner, the high Friday flow rates exist on

the lane for a much longer period of time than on weekday afternoons. Flow rates after

6:00 pm on Fridays become very high as a result of queue dissipation. Although a much

higher volume of vehicles is served on the transitway during a Friday PM peak period than

a normal weekday, traffic operations during the PM peak hour are severely impacted.

Comparing the two Fridays during which data was collected provides some

interesting observations. Flow rates on the "normal" Friday are lower than that observed

on the "worst case" Friday. The high variations in flow rates would indicate stop and go

conditions at the count site; which was located just west of the merge area. This is

indicated as occurring on the "normal" Friday. Flow rates during the "worst case" Friday

were observed to be consistent throughout the peak period; the transitway was observed to

queue within the merge area.

In terms of vehicle counts recorded at Silber, peak period and peak hour demands

are much different on Fridays than during normal weekday afternoons. Three-hour peak

period totals are approximately 25 percent higher than during weekdays. Peak hour vehicle

demands are not significantly higher than observed during mid-week operations. However,

the peak hour occurs approximately 45 minutes earlier than normally. This information is

presented in more detail in Table 14.

37

Table 13. Comparison of Weekday and Friday Afternoon 5-Minute Flow Rates, Katy Transitway at Silber

Observed Flow Rates in Vehicles/Hour Time Interval Wednesday (5[23[90) Friday (5[18[90) Friday (5 [25 [90)

"Normal" "Worst Case" 1104

4:00 - 4:05 pm 948 1116 1440 4:05- 4:10 1044 1116 1308 4:10- 4:15 984 1320 1128 4:15- 4:20 960 1140 1512 4:20-4:25 996 1164 1740 4:25- 4:30 984 1572 1536 4:30- 4:35 924 1584 1728 4:35- 4:40 1224 1368 1668 4:40- 4:45 1152 1656 1452 4:45- 4:50 1296 1776 1284 4:50- 4:55 1416 1584 1860 4:55- 5:00 1320 1524

1608 5:00 - 5:05 pm 1440 1536 1644 5:05- 5:10 1572 1800 1608 5:10- 5:15 1716 1596 1644 5:15- 5:20 1656 372 1512 5:20- 5:25 1500 1284 1524 5:25- 5:30 1500 1068 1572 5:30- 5:35 1572 1428 1500 5:35- 5:40 1596 972 1584 5:40- 5:45 1428 1044 1284 5:45- 5:50 1284 648 1668 5:50- 5:55 1476 1188 1704 5:55- 6:00 1464 1224

1116 6:00 - 6:05 pm 1332 552 1032 6:05- 6:10 1320 840 1488 6:10- 6:15 948 1692 1956 6:15- 6:20 936 1608 1932 6:20- 6:25 804 1368 1080 6:25- 6:30 816 1176 1044 6:30- 6:35 468 792 780 6:35- 6:40 648 744 792 6:40- 6:45 552 936 1056 6:45- 6:50 576 576 888 6:50- 6:55 252 792 804 6:55- 7:00 372 624

38

w \0

2100

1800

II :::l 0 1500 I

.......... (f) w ..J u H 1200 I w > z H

900 w I-<( II 3: 0 600 ..J LL

300

0

Figure 8. 1-10 Katy Transitway Flow Rates, Westbound at Silber, Weekday and Fridays

I-10 KATY TRANSITWAY FLOWRATES WESTBOUND AT SILBER -- WEEKDAY AND FRIDAYS

I I

I I

/ ~11 -+ I I N.-.N--~'N

: t I I I I I I

I + I I + I

I I -r-1\ I I I I \ I I I I I \ I I I I I I \ I I I I

I I ~ I ,;\- I I I I I ..- I I I I I f I I I I I I I I I I I I I I 1 I I 1 I I 1 I I ,' I I I I I I I 1 1 I I I I I -1 I I I I T I

I +I I I I I

:\ I

I~ \

"N-~ ~- ' ' \ .N- II

I I II II

+ \I 'N-f\ M \ N

v

1600 1700 1800

NOTES:


FLOWRATE=(5-Minute Oata)*12 N =Normal Weekday; + = 5/18/90 (Friday); * = 5/25/90 (Friday) Horizontal line denotes assumed capacity of 1500 vph.

1900

Table 14. PM Peak Hour and Peak Period Demands Observed at Silber

Time Period Wednesday (5L23L90) Friday (5L18L90) Friday (5 L25 L90) (% Diff)1 (% Diff)1 (vehicles) (vehicles)

4:00 - 5:00 pm 1104 1410 5:00 - 6:00 1517 1180 6:00 - 7:00 752 975

Total Peak Period 3373 3565

PM Peak Hour 151i 15253

NOTES: 1 Difference based upon Wednesday Data. 2 Peak hour = 5:00 - 6:00 pm 3 Peak hour = 4:15 - 5:15 pm 4 Peak hour = 4:20 - 5:20 pm


(vehicles)

+28% 1480 +34% -22% 1571 + 4% +30% 1164 +55%

+6% 4215 +25%

+ 1% 16074 + 6%

Travel time and speed studies were completed on the freeway mainlanes and

transitway in March 1990. The results of this study for the PM peak period (by 30-minute

headways) are presented in Table 15. Considering a similar trip along the transitway and

freeway, speeds on the transitway averaged 52 mph compared with 44 mph on the adjacent

freeway mainlanes. Maximum savings of 10 minutes are realized for trips beginning at 5:30

pm. A plot of transitway and freeway running speeds along this route is presented by

Figure 9. With exceptions of the fringes of the peak period, transitway users receive travel

time savings compared to a similar trip on the freeway mainlanes.

Table 15. Results of Travel Time Studies, PM Peak Period, March 1990

Start Exit Transitway at Gessner1 Exit Transitway at Western Terminus2

Time Transitway Triu Freeway Triu Transitway Triu Freeway Triu (minutes) (mph) (minutes) (mph) (minutes) (mph) (minutes) (mph)

3:30pm 7.32 46.3 6.72 50.4 14.52 52.1 13.75 55.0 4:00pm 7.68 44.1 8.90 38.1 14.62 51.7 15.85 47.7 4:30pm 6.62 51.2 9.88 34.3 13.82 54.7 17.53 43.1 5:00pm 6.73 50.4 10.73 31.6 13.73 55.1 20.63 36.6 5:30pm 6.80 50.0 12.87 26.3 13.95 54.2 23.85 31.7 6:00pm 7.00 48.4 9.78 34.7 15.33 49.3 17.17 44.0 6:30pm 6.40 53.0 7.35 46.1 13.43 56.3 14.58 51.9 7:00pm 7.95 42.6 7.53 45.0 16.05 47.1 14.30 52.9 Average 7.06 48.0 9.22 36.8 14.43 52.4 17.21 43.9

1 Trip length = 5.65 miles 2 Trip length = 12.60 miles

40

65

60

55 j 50

.c. c. E

45 0 w 40 w 0.. UJ

(!) 35 z H

+>- z 30 ....... z :::l a: w 25 (!) <( a: 20 w > <(

15

10

5

0

1500

T = Transitway

Figure 9. 1-10 Katy FreewayfTransitway Average Speeds, Westbound, PM Peak Period

I-10 KATY FREEWAY/TRANSITWAY AVERAGE SPEEDS WESTBOUND -- PM PEAK PERIOD

F, ... ..... "' y-- ~_,F-. ... ... ..... " ... ... " ..... ..... " ... r-_ " ... , ... - " ... -- " ... - .... --- f" ..... F"'

"' ... "' -..... "' - "' ... "' ..... ..... "' ..... "' 'F-- "' - "' -- "' - "' -- "' -r-

1600 1700 1800


Speed: F = Freeway Speed

... 'F

1900

Speed studies were also completed using automatic traffic counters at two locations.

This equipment will estimate the speed of a vehicle and record it within a specified 5-mph

range. Although speeds of individual vehicles are not reduced, the data (collected in 15-

minute intervals) can be used to identify specific operational characteristics of the

transitway. The results of this analysis for the PM peak period are presented in Table 16.

This data was collected in early April during weekday operations. Consider that the

counting equipment may not have recorded the speed of every vehicle, however, the sample

results provide insight as to transitway performance during outbound operations. For the

analysis of the PM period, only data collected along the Eastern Extension and at Silber

is presented. Speeds of vehicle approaching the merge area along the Eastern Extension

average about 40 mph. That observed over Silber is similar. This is most likely due to the

merging operation and geometries at this location.

Table 16. PM Peak Period Sample Speed Study Results

Eastern Extension Silber Time #Vehicles Avg Speed #Vehicles Avg Speed

4:00 - 4:15 pm 95 43.8 143 37.8 4:15- 4:30 114 38.9 198 36.0 4:30- 4:45 125 41.9 212 35.5 4:45 - 5:00 156 38.8 252 35.6

5:00 - 5:15 pm 196 37.4 307 33.8 5:15- 5:30 230 38.6 367 34.8 5:30- 5:45 246 39.8 358 33.2 5:45 - 6:00 237 38.3 371 32.7

6:00- 6:15pm 153 40.6 261 35.1 6:15- 6:30 136 39.8 280 34.7 6:30- 6:45 89 37.7 184 35.8 6:45- 7:00 110 40.5 172 36.2

NOTE: #Vehicles represents sample size for average speed determination; actual transitway flow rates may be higher.

Capacity Analysis

Level of Service (LOS) on the transitway is estimated using the Highway Capacity

Manual (~). The analyses use volume data collected during the first months of operation

of the Eastern Extension. The first analysis considers the transitway as a one-lane freeway

42

and estimates the LOS at the maximum loading point west of the Eastern Extension/Post

Oak merge. The LOS is based upon the observed transitway volume and criteria included

in Table 3-1 of the HCM. Because transitway volumes vary on a daily basis, only the

maximum observed demands are presented. Table 17 presents the transitway LOS

calculated using two assumptions of lane capacity. Considering these values which represent

the highest hour observed (usually occurring on Fridays), the transitway operates at LOS

D during the peak hour. Estimating the LOS using an assumed capacity of 1,500 vph

resulted in LOS F operations since the v / c ratio exceeds 1.0.

Table 17. Basic Section Level-of-Service, PM Peak Hour

Maximum Peak Start Date No. of Days Hour Demand

1-09-90 2 1186 1-12-90 1 1538 2-16-90 2 1581 4-10-90 3 1632 4-25-90 2 1884 5-17-90 2 1525 5-21-90 5 1607

1 Based upon maximum capacity assumed at 2,000 vph/lane. 2 Based upon maximum capacity assumed at 1,500 vph/lane.

HCM Method1

ill LOS

0.59 B 0.77 c 0.79 D 0.82 D 0.94 D 0.76 c 0.80 D

Assumed Capacity2

ill LOS

0.79 D 1.03 F 1.05 F 1.09 F 1.26 F 1.02 F 1.07 F

If the Post Oak entry volume was assumed to be a freeway section with a one-lane

ramp entering from the Eastern Extension, a capacity analysis of the PM peak hour ramp

merge can also be completed. Considering the transitway demands of April 1990 as

presented by Figure 6, a merge volume of 1,498 vph results in LOS D operations. If the

Eastern Extension was assumed as the through lane and the Post Oak Terminus volume was

assumed as a left-hand entrance, similar results would be realized. The LOS D operation

indicates a potential problem within the merge area. This type of operation has been

defined as:

"At level-of-service D, smooth merging becomes difficult to achieve. Both entering

and lane 1 vehicles must frequently adjust their speed to avoid conflicts in the merge

area. Slowing in the vicinity of diverge areas is also significant. Turbulence from

merge and diverge movements will affect several freeway lanes. At heavily used

on-ramps, ramp queues may become a disruptive factor" (5.).

43

A final capacity analysis was completed examining operations at the Post Oak

Terminus of the transitway. Using the results of the turning movement studies, the most

efficient signal phasing (for each hour) at the intersection was determined using the

TRANSYT-7F signal optimization model. To simplify this effort, simple 4-phase signal

timing without overlaps was assumed for the analysis. The program was allowed to select

the appropriate cycle length resulting in the least amount of total intersection delay. Table

18 presents the results of the 4:00- 7:00pm peak period for studies completed in October

1989, January 1990, and March 1990. The implementation of the Eastern Extension has

significantly improved the LOS at the intersection. A 17 percent reduction in total traffic

volume has provided for an approximate 50 percent reduction in overall intersection delay.

In terms of vehicles that access the transitway, 18 percent enter from southbound Post Oak,

36 percent enter from westbound Old Katy Road, and 46 percent from northbound Post

Oak. The westbound approach for those destined to the transitway has decreased from

1,695 vehicles in October 1989 to 436 vehicles in March 1990. This approximate 75 percent

decline in vehicle demand is a direct result of the opening of the Eastern Extension.

Table 18. Summary of PM Peak Period Operations, Katy Transitway Post Oak Terminus

Month Total Volume Total Delay Average Delay LOS (veh/hr) (veh-hrs) (secjveh)

October 1989 8383 101.12 43.4 E January 1990 8387 80.27 34.5 D March 1990 6919 48.59 25.3 c

Summacy of PM Peak Period Operations

Based upon the data presented in this report, the Katy Transitway is operating at

a "less than desirable" level of service during the PM peak period. Although this type of

operation is usually experienced on Fridays, it could easily spread to other weekday periods.

The transitway operates near LOS D conditions. The most critical location is the merge

between the Eastern Extension and the Post Oak entrance. Since the Eastern Extension

became operational, total transitway peak hour demand has increased by 15 percent to

1,498 vph. Demands west of Gessner have remained constant while those exiting at

Gessner have increased from 344 vph to 744 vph (January - April), an increase of

44

approximately 116 percent. As with the AM peak period, the 1.5 mile Eastern Extension

has attracted additional carpools to the transitway.

As indicated by Table 12 and Figure 7, flow rates at or exceeding 1,500 vph exist on

the transitway between 5:00pm and 6:00pm. On Friday afternoons, this period of time has

been observed to begin as early as 4:00 pm with much higher flow rates (Figure 8). Peak

period vehicle demands are usually 25 percent higher on the transitway on Fridays when

compared to weekdays; peak hour demands are similar because of congestion on the lane.

Queueing on the merge area and along the Eastern Extension have been observed on

Fridays.

In summary, the transitway is operating at or near capacity during normal weekday

non-incident conditions. Demand increases of as little as 5 percent in the peak hour could

cause congestion on the lane during weekday operations. Excessive transitway demands on

Friday afternoons causes queued traffic and delays on the transitway. Some measures to

manage transitway demand during the PM peak period either on Fridays or the entire

weekday may be necessary.

45

OPTIONS FOR MANAGING DEMAND DURING THE PM PEAK PERIOD

As examined for the AM peak period, four options exist for demand management

during the PM peak period. Each of these options will be examined in this section of this

report. Since more problems with transitway congestion is observed on Fridays, each

option is examined as to its effectiveness for daily or Friday only control.

Voluntacy Spreading of Peak-Hour Demands

Since the attempt to achieve voluntary participation in the adjustment of demand was

unsuccessful for the AM peak period, it is unlikely that a similar effort in the PM would

produce positive public response. The effectiveness on Fridays would be questionable since

high demands extend for a 2-hour period.


Implementing this option of mandatory demand management during the AM period

had a positive effect in reducing transitway congestion during the peak hour. A similar

impact could be expected should this strategy be used during the PM peak period.

However, high flow rates could be expected during time periods just prior to the restricted

period. Based on data collected in April 1990, only about 10 percent (343 out of 3,566

vehicles) of the carpools on the transitway during the PM peak period have occupancy

levels above 2 persons. Impacts to transitway operations could be expected to be similar

to that experienced during the AM peak period. Selecting the proper time to impose the

3 + restriction could be somewhat difficult. In order for the transitway operating hours to

be consistent, any 3 + restricted time periods would need to be the same for all weekdays.

It would be almost impossible to adequately sign for day and time specific occupancy

restriction (i.e., restrictive periods must be the same for Mondays through Fridays).

Considering the transitway demands, an occupancy restriction during a normal weekday

would be needed between approximately 4:45 pm - 6:00 pm. However, on Fridays the

period would be necessary beginning at 3:45 pm. Although a 3 + period on all days

between 4:45 pm and 6:00 pm would be beneficial to HOV operations, congestion on the

transitways could be experienced between 3:45pm and 4:45pm. If this option is selected

46

for implementation, it is recommended that the 3 + restriction be imposed between 4:45pm

and 6:00 pm. Any congestion on the transitway that occurs before that time would be

cleared before the peak hour began.

Require Authorization durin~: the Peak Hour

If the concept of authorization were to be re-introduced during one peak period, it

should be used for both peak periods. This strategy would be similar to the concept as

proposed for the AM peak period. Time period for the authorized restriction should be

between 3:30 pm to 6:30 pm. A more detailed explanation of the authorization process is

explained in a previous section of this report.

Close and/or Meter Entrance Ramps durin~: the PM Peak Hour

The final option considered involves reducing access to the transitway for all or part

of the peak hour by either closing ramps or metering ramp volumes. When considering

this option for the AM period, concern was expressed for favoring either long or short trips.

However, the close proximity of the two PM access locations eliminates this concern.

Based upon available field data, about 35 to 40 percent of transitway traffic enters the lane

via the Post Oak entrance. Possible problems with metering both approaches to the merge

area are examined below.

If the Eastern Extension were selected for metering, two specific problems are

noted. The first being that the higher merge volume would be metered, resulting in

queueing on the transitway. If this metering were imposed just prior to the merge, the

queue would develop in a narrow section of the transitway. It is not possible to pass

disabled vehicles in a portion of this section of the transitway; a stall would completely

block the lane. The likelihood of stalled vehicles could increase as each vehicle waits in

the ramp signal queue.

Ramp metering manages demand by controlling flow rates and causing diversion

along a parallel route. To accomplish diversion from the transitway Eastern Extension,

the presence of a metering queue must exist at or prior to the access point or the

47

approaching traffic must be informed of the operation of the controls in order to make a

safe diversion. Because of the slip ramp access from the freeway mainlanes, this cannot be

safely implemented near the access point. Therefore, metering the Eastern Extension of

the Katy Transitway is not recommended.

The option of metering the Post Oak entrance to the transitway is much more easily

accomplished. This could be done by installing a ramp meter on the flyover ramp prior to

the merge. A freeway ramp meter signal could be installed on the bridge that would be

visible to the transitway and would not impact vehicles on the freeway. The signal should

be placed near the crest of the hill and not on the downslope. The major problem will

be the meter queue that could back out of the transitway entrance and into the Post Oak

at Old Katy Road entrance. The distance from the top of the flyover to the surface street

is approximately 800 feet; about 30 automobiles could be adequately stored before the

queue would impact the signalized intersection. However, it would not be physically

possible to enforce violations of the ramp signal because of geometries.

An alternative to a signalized meter would be a manual closing of the Post Oak

entrance. This would allow for demand management if it is desired for implementation

only on Fridays. The transitway crew and/ or Transit Police could be stationed at the

entrance and not allow vehicles on the lane. Buses and vanpools could then be selectively

allowed on the lane. The changeable message sign could be used to inform motorists that

the HOV lane is full and that the freeway or other alternate route must be used. This

strategy could be implemented as traffic congestion increases on the transitway and before

queueing occurs. A set of detailed guidelines to be used for implementation of this plan

must be developed if this approach is to be used. This option would be low cost for

implementation and could solve the existing Friday congestion concerns while not impacting

normal weekday operations.

Recommendations

Based upon the operations of the Katy Transitway during the PM peak period, the

following options for controlling demand are recommended:

48

1. Consider implementing the authorization process based upon a time/

occupancy/ capacity restraint. This option for managing demand should be

seriously considered if vehicle demand on the transitway continues to increase.

Although this does require additional cost and effort by METRO to

implement and monitor, it does allow for maximum use of the transitway by

buses, vanpools, and carpools at all occupancy levels while maintaining a

high level-of-service; and

2. Implement a plan that would allow for either signal or manual (short term)

control at the Post Oak entrance to the transitway. A detailed set of

operating guidelines should be developed prior to implementing this option.

Implementing the second recommendation is easily done without a large capital

investment. However, with increasing 2 + carpool demands, this solution may be a viable

alternative for demand management for a 1-2 year period. It is anticipated that a 3 + restriction during the peak hour or the authorization procedure suggested may also be

necessary when ramp control of the Post Oak adequately control demand.

Possible negative reaction from the public should also be expected, especially if any

type of access is restricted. Therefore, the selection of any demand management strategy

must be carefully considered. The intent of the transitway of providing high speed travel

and reliable travel time and its appearance of being adequately utilized must be maintained.

49

REFERENCES

1. Christiansen, D.L. and W.R. McCasland, "Options for Managing Traffic Volumes

and Speeds on the Katy Transitway," Research Report 484-6, Texas Transportation

Institute, April 1988.

2. Christiansen, D.L. and D.E. Morris, "The Status and Effectiveness of the Houston

Transitway System, 1988," Research Report 1146-1, Texas Transportation Institute,

July 1989.

3. Christiansen, D.L. and D.E. Morris, "The Status and Effectiveness of the Houston

Transitway System, 1989," Research Report 1146-2, Texas Transportation Institute,

March 1990.

4. Mounce, J.M. and R.W. Stokes, "Manual and Planning, Designing, and Operating

Transitway Facilities in Texas," Research Report 425-2, Texas Transportation

Institute, September 1985.

5. "Highway Capacity Manual," Transportation Research Board, Special Report 209,

1985.

6. "The Effects on Transitway Utilization of the Vehicle Authorization Process,"

prepared for the State Department of Highways and Public Transportation by Texas

Transportation Institute, August 1987.

50

Documents

Technical Memorandum Work Order #4-F Prepared for ... · 6 9 15 17 19 19 19 23 26 28 30 30 40 42 44 46 46 46 47 47 48 50 . LIST OF FIGURES Page ... reopening of school, the peak-hour