Road accidents are caused by a combination of factors related to road conditions, driver behavior, and vehicle characteristics. Poor road conditions such as roughness, rutting, cracking, and low skid resistance are contributing factors in a significant percentage of accidents. Maintaining adequate road quality through measures such as resurfacing and realignment can reduce accidents by 25-60%. Proper maintenance and repair of road defects can lower accident rates and safety costs. Monitoring road measurements like IRI and PSI that indicate roughness and conducting friction testing helps identify high-risk locations and control skid resistance.

1. BLOODY PAVEMENT
Creating Quality Road Surface To Ensure Prolonged Safer Road
Use
Mona Khafagy, MSC.,EIT.
Pavement Expert
Highways & Transportation Engineer
monakhafagy@aucegypt.edu

2. 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

3. CAUSES OF ACCIDENTS
The Handbook of Highway Engineering, Australia,2006

4. 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)
CAUSES OF ACCIDENTS

5. 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

6. 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)

7. According to Federal Highway Administration, Millor& Zaloshnja 2008. (2)
Costs of Improper and Hazardous Road Surface

8. (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

9. 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

10. Surface Condition Risk Factors
• Roughness (IRI, PSI)
 Unevenness (Surface irregularities) and potholes;
 Raveling (Loose materials);
 Patching repairs;
Splashing
Rutting
• Skid resistance (SFC)

11. 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)

12. Pavement Characteristics Affecting Safety
It’s 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

13. 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)

14. Pavement friction is affected by
related wear and raveling (6).
Roughness Defects Affecting Safety
Pavement Raveling
Patching

15. Unevenness:
Roughness Defects Affecting Safety
Unevenness
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)

16. Pothole filled with water
Pothole
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

17. Splash
Roughness Defects Affecting Safety
•Splash generated by vehicles travelling on wet
roads.
•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)

18. HMA Types With Enhanced Frictional Properties (15)
SUPERPAVE SURFACE COURSE STONE MASTIC ASPHALT OPEN GRADED FRICTION COURSE
Splash
Open structure (gradation ) can reduce noise and splash
How open graded mixture design reduces splash: (18)
https://www.youtube.com/watch?v=t3YJOZRQ224&hd=1

19. Rutting
Roughness Defects Affecting Safety
Rutting
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.

20. Hydroplaning
Hydroplaning occurs when a layer of water
builds up between your vehicle’s 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
RPM’s as the wheels spin on
top of the water. (15)
Roughness Defects Affecting Safety
Rutting

21. IRI; represents the overall pavement
distress condition and is widely used
Roughness Defects Measurements
1.5< IRI<3 fair
IRI >3 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 <1.5
will lower risk under adverse
weather condition. (8)

22. 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

23. 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

24. 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

25. SKID RESISTANCE
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)

26. Skid Resistance Measurements
Friction Coefficient <0.45
Friction Coefficient < 0.30
Friction coefficient < 0.25
Accident risk 20 times
Accident risk 300 times
Accident risk 1000%
Like adding dust of
wet snow
Road Safety Research and the County Surveyors’ Society in UK, 2004

27. Effect of wet pavement condition
Change in sever- injury probabilities by driver group and road way surface (6)
Skid Resistance Measurements

28. 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
locations;
Managing the in situ frictional
resistance of a road through
systematic network surveys.
Controlling the specification of
microtexture and macrotexture
(PSV and AAV tests
specifications)

29. Fallacious Information (19)
Egyptian Case

30. According to Khaled Abbas, 2002 (17)
Cairo Alexandria agriculture road proved to be the highest
rate of accident per kilometer with a record of 1.99
accident/km/year which is above the corresponding
network value by 37%. This road is the most deteriorated
road in Egypt. There is a reasonable cause of this high
severity of this road. We can correlate high accident rate
to the pavement condition.
Egyptian Case

31. Open letter
Nesma Nafea wrote;
Dear Egypt’s General Road Authorities,
On the 25th of February, 2010 my best friend was driving home from
university – less than a 10 minute drive. Unfortunately, it was hailing and
raining like Egypt has never witnessed before and the roads were slippery
BECAUSE THERE ISN’T A PROPER DRAINAGE SYSTEM
INSTALLED!
Egyptian Case
Dear Egypt’s Road Authorities, You Killed My Best
Friend… 2014

32.  the required funding for road maintenance in Egypt is
estimated around $ 700 million per year, yet only $ 70
million is available.
 In other words, every km of Egyptian road network
will only be maintained every 33 years.
 Every $ 1 dollar spent now on road maintenance will
save Egypt $5 dollar in 5 years.
Egyptian Case
World bank, 2014
Increase funding for road maintenance-
Investing in road maintenance should be a priority

33. Egyptian Case
Recommendation
In-depth studies or specific accident simulations
including the road infrastructure (virtual road) are
essential
According to the world bank report, Egypt should have
a plan to scale up the funding for road maintenance

34. References
1. "Heartburn Highways, The Cost To Motorists Of Traffic Congestion, Traffic Crashes And Deteriorated
Pavements And The 50 Roads And Highways In Colorado That Cause Drivers The Most Stress”, TRIP,
Washington, D.C., October 2005.
2. “Pavement Surface Characteristics Relationship to Crashes Overview” , Applied Pavement Technology.
Kelly Smith , 2010 .
3. “A study of factors affecting highway accident rates using the random-parameters”, Tobit model Panagiotis
Ch. Anastasopoulosa, Fred L. Manneringb, Venky N. Shankarc, John E Haddockd, Accident Analysis and
Prevention 45 (2012) 628– 633.
4. European Road Safety Observatory Report (2006) Roads, Project co-financed by the European
Commission, Directorate-General Transport and Energy ,2007.
5. An assessment of the skid resistance effect on traffic safety under wet-pavement conditions José M.
Pardillo Mayora∗, Rafael Jurado Pi ˜na, Department of Civil Engineering: Transport, Technical University
of Madrid (UPM), 28040 Madrid, Spain, May 2009
6. The effects of road-surface conditions, age, and gender on driver-injury severities, Abigail Morgana, Fred
L. Manneringb, a School of Civil Engineering, Purdue University, West Lafayette, IN 47907, USA, April
2011
7. Effects of Asphalt Pavement Conditions on Traffic Accidents in Tennessee Utilizing Pavement Management
System (PMS), Stephen Richards, Ph. D., P.E., Southeastern Transportation Center University of Tennessee,
Knoxville August, 2008
8. Preliminary Results towards Developing Thresholds for Pavement Condition Maintenance: Safety
Perspective, Srinivas S. Pulugurtha1, Vincent Ogunro, Miguel A. Pando, The University of North Carolina
at Charlotte, USA, 2013
9. Tyres, road surfaces and reducing accidents: a review, A report on research carried out for the AA
Foundation for Road Safety Research and the County Surveyors’ Society, John c Bullas,2004.

35. 10. COMPARISON OF FUZZYAND NEURAL CLASSIFIERS FOR ROAD ACCIDENTS
ANALYSIS, By Tarek Sayedl and Walid Abdelwahab , Univ. of British Columbia,
Vancouver,1998
11. Mining and Analysis of Traffic Safety and Roadway Condition Data, By Dr. Sara J. Graves,
Information Technology and Systems Center
12. Road Safety, Nobuhiro Uno, Yasunobu Oshima, and Russell G. Thompson.
13. Interaction between Powered Two-Wheeler Accidents and Infrastructure, Author: Peter Saleh,
AIT Austrian Institute of Technology,2010.
14. The Handbook of Highway Engineering, chapter 4 “Highway Safety “ , Ian Johnston, Monash
University, Victoria, Australia, 2006.
15. FRICTIONAL CHARACTERISTICS OF PAVEMENTS, JOHN EMERY , 2007.
16. Hydroplaning, Telcom Insurance Group, Monthly Loss Prevention Program.
17. Traffic safety assessment and development of prediction models for accident on rural roads in
Egypt, khaled Abbas, king Faisal university, 2002.
18. Asphalt pavement alliance, partnership of the Asphalt Institute, National Asphalt Pavement
Association and the State Asphalt Pavement Associations. http://driveasphalt.org.
19. Statewide Local Streets & Roads Needs Assessment , Moraga Town Council, February 24, 2010.
20. faculty of economic and political science, statistical analysis department, 2011
21. Pavement Surface Characteristics Relationship to Crashes, Pavement Evaluation Conference,
Roanoke, VA, October 2010.
References