Bloody Pavement

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  • BLOODY PAVEMENT Creating Quality Road Surface To Ensure Prolonged Safer Road


    Mona Khafagy, MSC.,EIT. Pavement Expert Highways & Transportation Engineer

  • Ref: Univ. of British Columbia, Vancouver,1998 (10)

    CAUSES OF ACCIDENTS Road crashes occur when a number of adverse factors COMBINE to cause a failure of the traffic system


    The Handbook of Highway Engineering, Australia,2006

  • According to Federal Highway Administration (Miller & Zaloshnja 2009) (2)

    Roadway conditions are a contributing factor in: 31% of total crashes

    52% of fatalities (resulting from crashes)

    38% of non-fatal injuries (resulting from crashes)


  • IN addition to the suffering and grief that they cause to those injured or killed and their loved ones. Motor vehicle crashes carry a cost to individuals that includes Medical Costs, Economic Costs,

    Household Productivity, Property Damage And Travel Delays (1)

    THE cost to operate and maintain a vehicle increases. These additional vehicle operating costs Include Accelerated Vehicle Depreciation, Increased Vehicle Repair Costs,

    Additional Fuel Consumption and More Rapid Tire Wear. (1)

    Costs of Improper and Hazardous Road Surface

    U.S. Department of Transportation's National Highway Traffic Safety Administration (NHTSA),2002

  • Every $100 million spent on needed highway safety improvements will result in 145 fewer traffic fatalities over a 10-year period. (1)

    Resurfacing pavements results in 25% reduction in fatal crashes, Realigning roadways results in 50% reduction.(1)

    Converting two-lane rural roads into four lanes routes reduces accident by between 40 to 60%. (1)

    Costs of Improper and Hazardous Road Surface

    $1.1 billion per year, or $368 per motorist is the safety cost of roads that lack desirable safety features in Colorado. (1)

  • According to Federal Highway Administration, Millor& Zaloshnja 2008. (2)

    Costs of Improper and Hazardous Road Surface

  • (1) According to new York department of motor vehicles, based on an analysis of federal highway safety data. 13) In the accident analysis conducted in MAIDS (motorcycle accident in depth analysis)by (ACEM (association des constructeurs europeens de motorcycles, 2003).

    Road surface defects were present in

    1/3 (ONE THIRD) of fatalities in New York. (1)

    30% of accidents in Austrian. (13)

    Maintenance defects were reported in

    15.8% in Japan and Asian megacities fatality accidents. (12)

    Contributing factor in 17.1% of crashes. (12)

    Road Condition Contribution Percentage

  • Road defects Causing Accidents

    Caused or Contributed to approximately 30,000

    collision throughout new York in 2011:

    Defective Pavement; contribute to 500 accidents, three death and 300 injuries.

    Side Obstruction ; a factor in 2,157 crashed six death-

    and 734 injuries

    Improper/ Inadequate Lane Marking; a factor in 159

    collusion causing 57 injuries

  • Surface Condition Risk Factors

    Roughness (IRI, PSI)

    Unevenness (Surface irregularities) and potholes;

    Raveling (Loose materials);

    Patching repairs;



    Skid resistance (SFC)

  • Pavement Characteristics Affecting Safety

    ROUGHNESS Pavement roughness affect riding quality , vehicle life , fuel consumption , delay cost. (7)

    AS the pavement roughness defects ( patches, potholes, and unevenness) increase, the contact area between vehicle tire and pavement will decrease thus leading to a lower brake friction. (7)

  • Pavement Characteristics Affecting Safety

    Its also the cause of loss load accidents, when vehicle is pounced up and down in extremely rough pavement , the bouncing result in vehicle losing their parts or loads. (7)


  • Roughness, Crack Sealing And Friction are highly correlating (6) Crack Sealing

    Roughness Defects Affecting Safety

    Deteriorated pavement Pavement texture and friction is affect by pavement deterioration, rutting, cracking , raveling (6)

  • Pavement friction is affected by related wear and raveling (6).

    Roughness Defects Affecting Safety

    Pavement Raveling


  • Unevenness:

    Roughness Defects Affecting Safety


    Is a measure of the irregularity of a road surface

    Occurred due to; the axial load of vehicles the traffic volumes the weather conditions the quality of materials the construction techniques

    Unevenness causes bouncing of vehicle up and down, the bouncing may result in vehicle losing their parts and loads (6)

  • Pothole filled with water


    Roughness Defects Affecting Safety Unevenness:

    Water concentration on these deteriorations increases the risk of vehicles skidding

    Generates dangerous avoidance maneuvers, losses of control or mechanical breakdowns of vehicles

  • Splash

    Roughness Defects Affecting Safety

    Splash generated by vehicles travelling on wet


    It is hazard when road speeds exceed

    approximately 40 mile/h.

    Splash results from the turbulence created by

    vehicles entraining and dispersing water

    droplets Splash from lorry tyres in wet weather was found to be a

    problem that had bothered 82 % car drivers and

    motorcyclists in 1983. (9)

  • HMA Types With Enhanced Frictional Properties (15)


    Splash Open structure (gradation ) can reduce noise and splash

    How open graded mixture design reduces splash: (18)

  • Rutting

    Roughness Defects Affecting Safety


    Rutting acts like a channeled wheel path

    High rut depth increase accident rates on all roadway segments (3) Water accumulates in the rut path causing Hydroplaning.

  • Hydroplaning Hydroplaning occurs when a layer of water builds up between your vehicles tires and the road surface causing a loss of traction and possible loss of control. (16)

    If your drive wheels are hydroplaning, you might notice an increase in engine RPMs as the wheels spin on top of the water. (15)

    Roughness Defects Affecting Safety Rutting

  • IRI; represents the overall pavement distress condition and is widely used

    Roughness Defects Measurements

    1.5< IRI3 poor

    IRI < 1.5 m/km Good

    Every unit increase in IRI, crash frequency increases by 1.96 times(7), And the probability of crash increases by 45% (8)

    Every decrease in IRI by 1m/km will save cost of accidents 321 million dollars per year. (8)

    IRI up to 4 increases the repair & maintenance cost of vehicle and trucks by 10% and up to 5 increase it by 50%.(8)

    Targeting and maintain IRI

  • Pavement deteriorated by one unit of PSI, accident frequency would increase by 1.4 times. (7)

    PSI; is an index calculated by several physical measurements including slope variance, rut depth, cracking, and patching. PSI is a significant prediction variable for all types of accident model. (7)

    Roughness Defects Measurements

    PSI = 1 totally deteriorated pavement

    PSI = 5 most comfortable

    riding quality

  • Rut Depth Increases in rut depth increase accident rates in

    94.27% of the roadway segment.(3)

    7.6mm rut depth is the point at which significant

    increase in accident to appear.

    30% of crash sites have rut values between 4.8

    mm and 7.2 mm. (11)

    Roughness Defects Measurements

  • Pavement Characteristics Affecting Safety

    SKID RESISTANCE (transversal friction)

    Skidding occurs when the coefficient of friction between the tire

    and the road is inadequate to maintain full contact. (9)

    The wet road condition presents a much more complicated situation Wet pavement crash rates decrease by 68% as skid resistance values increase.(5)

    The two main characteristics of pavement surface affect skid resistance:

    microtexture and macrotexture


    Is highly affected by Aggregate Properties (corresponding

    rate of polishing), throughout control tests (PSV, AAV). (9)

    Pavement Characteristics Affecting Safety

    25% of all wet road accidents are related to skidding

    conditions in UK . (14)

  • Skid Resistance Measurements

    Friction Coefficient

  • Effect of wet pavement condition

    Change in sever- injury probabilities by driver group and road way surface (6)

    Skid Resistance Measurements

  • Tips to control skid resistance

    Dynatest 1295 Pavement Friction Tester

    Using field results of frictional

    resistance to investigate accidents

    and to identify high-risk accident


    Managing the in situ frictional

    resistance of a road through

    systematic network surveys.

    Controlling the specification of

    microtexture and macrotexture

    (PSV and AAV tests


  • Fallacious Information (19)

    Egyptian Case

  • Accordin