Accident Investigations &Risk Management

Collection Of Accident Data, Assessment Of Road Safety, Methods To Identify And Prioritize Hazardous Locations And Elements, Determine Possible Causes Of Crashes, Crash Reduction Capabilities And Countermeasures, Effectiveness Of Safety Design Features, Accident Reconstruction, Condition And Collision Diagram.

1. Module - 1
ROAD SAFETY ENGINEERING
Collection Of Accidental Data
• Accident data collection is the systematic gathering of facts and evidence related to
road accidents.
• The purpose is to understand the causes and contributing factors, identify black spots,
and design preventive measures to improve road safety.
Objectives of Collecting Accident Data
• Identify accident-prone locations (black spots).
• Analyze patterns (time of day, weather, type of collision).
• Assist in risk management and highway design improvements.
• Support enforcement agencies (National and State bodies) for law-making and
implementation.
• Provide inputs for insurance, legal claims, and safety audits.
Types of Accident Data
• Administrative Data – From police reports, FIRs, hospital records.
• Engineering Data – Road geometry, traffic volume, signage, surface condition.
• Behavioral Data – Driver’s age, alcohol/drug use, fatigue, speeding.
• Environmental Data – Weather, visibility, lighting conditions, time of accident.
Sources of Accident Data
• Police Records – First Information Reports (FIRs) and accident investigation forms.
• Hospital & Emergency Services – Injury severity, number of casualties.
• Insurance Companies – Claims data for financial assessment.
• Traffic Surveillance Systems - These tools can capture real-time information about
vehicle speeds, traffic flow, and violations, which can help in post-accident analysis
• Surveys & On-site Measurements – Skid marks, debris, vehicle position.
• Technology Sources – CCTV footage, drones, automatic traffic recorders.

2. Methods of Data Collection
• On-site Observation – Investigators visit the accident location immediately after the
crash to observe and record visible evidence such as skid marks, damaged guardrails,
debris, or weather conditions. This helps capture perishable details that may vanish later
due to traffic or cleaning operations..
• Interviews – Statements are collected from drivers, passengers, eyewitnesses, and
nearby residents to understand the sequence of events, driver behaviour, and
contributing factors like overspeeding or signal jumping. Interviews add human-
behavioural context to the physical evidence.
• Photographic & Video Evidence – High-resolution photos and videos are taken to
document vehicle damage, road surface condition, signage visibility, lighting, and
surrounding features. This visual record supports later analysis and reconstruction of
the crash.
• Sketching & Mapping – Collision diagrams and spot maps are drawn to show the
relative position of vehicles, direction of movement, and point of impact. These
sketches help identify accident-prone spots and recurring patterns on the roadway.
• Statistical Compilation – After collecting raw data from the field, it is tabulated and
summarised to identify trends—such as accident frequency, time of occurrence, and
severity. This statistical summary becomes the basis for future road-safety analysis
and policy decisions.
Importance of Accident Data Collection
• Helps in black spot identification and prioritizing road safety projects.
• Provides factual evidence for improving highway design and traffic control.
• Aids in risk management by assessing accident frequency and severity.
• Supports policy making (e.g., speed limit laws, helmet rules).
Assessment Of Road Safety
• Road Safety Assessment is the process of systematically evaluating the safety
performance of a road or road network to identify risks, hazardous locations, and
improvement opportunities.
• It focuses on proactive prevention by identifying unsafe conditions before accidents
happen and also analyzes past crash data.

3. Types of Road Safety Assessments
a) Reactive Assessment
• Based on past accident data (police reports, hospital records, etc.).
• Focuses on sites with high crash frequency/severity.
• Examples: Black spot studies, crash mapping.
b) Proactive Assessment
• Focuses on predicting future risk even before accidents occur.
• Done through field inspections, audits, and safety checks.
• Useful for newly built roads or roads with no crash history.
Key Techniques Used
i. Road Safety Audits (RSA)
• Formal inspection of existing or planned roads by a qualified team.
• Detects potential hazards for all road users.
• Done during design, construction, and post-opening stages.
ii. Crash Data Analysis
• Uses accident statistics, diagrams, spot maps.
• Identifies patterns like:
o Time-of-day trends
o Vehicle type involvement
o Impact point, road condition
iii. Road User Behavior Study
• Observes pedestrian behavior, jaywalking, speeding, red-light violations.
• Helps in planning educational or enforcement campaigns.
iv. Traffic Flow Assessment
• Studies volume, speed, delays, queue lengths.
• Helps optimize signal timing, lane marking, or junction design.
Methods to Identify and Prioritize Hazardous Locations and Elements
• Hazardous locations (also known as accident-prone spots or black spots) are specific
road areas with a high frequency or severity of crashes.
• Identifying and prioritizing such locations helps road authorities plan corrective
measures, improve infrastructure, and reduce accidents and fatalities.

4. What Are Hazardous Locations?
• Locations where:
o Multiple crashes occur frequently (3 or more/year)
o Crash severity is unusually high (fatal/injury crashes)
o Specific road features contribute to accidents (blind curves, poor signage,
junctions)
Methods to Identify Hazardous Locations
1. Accident Frequency Method
Count the number of crashes at a location over a time period.
Example:
At Junction A:
• 7 accidents occurred in the last 12 months.
At Junction B:
• 2 accidents occurred.
Conclusion: Junction A is more hazardous based on frequency.
2. Accident Rate Method
Crash rate per vehicle flow. Used when traffic volume differs between roads.
Example:
• Junction A: 7 crashes, 70,000 vehicles/day
• Junction B: 2 crashes, 1,000 vehicles/day
Crash Rate (simplified) = (No. of Crashes / Traffic Volume) × 10⁶
• A: (7 / 70,000) × 1,000,000 = 100
• B: (2 / 1,000) × 1,000,000 = 2,000
Conclusion: Junction B is more hazardous in terms of crash rate.
Even if accidents are fewer, a road with less traffic and more crashes is riskier.
3. Severity Index Method
• Weights crashes based on injury levels (e.g., fatal = 5, serious = 3, minor = 1).
• Identifies areas with high-impact crashes, not just frequent ones.
Example 1:
At Location X (in 1 year):
• 0 fatal = 0 points
• 2 serious = 2 x 3 = 6 points

5. • 4 minor = 4 × 1 = 4 points
Total = 10 severity score
At Location Y:
• 0 fatal
• 2 serious = 2 x 3 = 6 points
• 3 minor = 3 points
Total = 9 severity score
Conclusion: Location X is more critical because it has a higher severity score.
Example 2:
At Location X (in 1 year):
• 1 fatal = 5 points
• 0 serious = 0 points
• 4 minor = 4 × 1 = 4 points
Total = 09 severity score
At Location Y:
• 0 fatal
• 2 serious = 2 x 3 = 6 points
• 3 minor = 3 points
Total = 9 severity score
Conclusion:
• Severity score is the same → both locations are equally critical based on severity.
• However, Location X includes a fatal crash, while Y has only injuries.
Depending on policy, you may prioritize fatality over multiple injuries, even if the score
is equal.
Example 3:
At Location X (in 1 year):
• 1 fatal = 5 points
• 0 serious = 0 points
• 0minor = 0 points
Total = 05 severity score
At Location Y:
• 0 fatal
• 1 serious = 1 x 3 = 3 points

6. • 3 minor = 3 points
Total = 9 severity score
Conclusion: Despite Location Y having a higher score, Location X had a fatal crash, which
typically indicates a more serious safety issue
4. Crash Cost Method
Attach a monetary value to each crash type (used in planning budgets).
Example:
At Spot A:
• 2 deaths × ₹10 lakhs = ₹20 lakhs
• 3 serious injuries × ₹5 lakhs = ₹15 lakhs
Total crash cost = ₹35 lakhs
At Spot B:
• 6 minor injuries × ₹50k = ₹3 lakhs
Conclusion: Spot A is a priority for safety funding.
5. Spot Speed Study
Measure the speed of vehicles at a location to detect overspeeding.
Example:
You conduct a radar speed check near a school and find that 60% of vehicles go above 50 kmph.
Conclusion: Speeding is a safety concern here → consider speed humps or signage.
6. Conflict Technique
The Conflict Technique is used to identify potential accident spots, even if no crash has
occurred yet.
Instead of waiting for a collision to happen, we observe dangerous situations like:
• Sudden braking
• Sharp turns
• Near-misses
• Honking, hesitation, or evasive maneuvers
These are called conflict events.

7. Why Use It?
Not all dangerous spots have a crash history – especially in low-traffic or newly built areas.
This method helps us act proactively, rather than reacting after accidents occur.
Example Explained
Let’s say you observe a busy roundabout in your city for 1 hour. You record:
• 20 instances where cars suddenly braked and honked at merging traffic
• 5 cases where cyclists almost hit pedestrians while crossing
• 3 risky lane changes due to unclear markings
These are conflict points — not crashes, but high-risk interactions that could easily turn into
accidents.
How it’s Done (Field Study Tips):
1. Choose an intersection or segment with suspected safety issues.
2. Observe and manually record near-miss events OR use CCTV/drones.
3. Classify types of conflict (e.g., pedestrian vs vehicle, vehicle vs cycle).
4. Count how frequently each type occurs in a given time.
5. Prioritize spots with frequent or severe near-miss incidents.
7. Road Safety Audits (RSA)
A Road Safety Audit is a formal, structured process where a team of independent safety experts
evaluates the safety aspects of a road (or road project) to identify potential hazards.
Possible Causes of Crashes
Road traffic crashes do not happen randomly — they are caused by a combination of human,
vehicular, environmental, and infrastructural factors. Understanding these causes is essential
for planning effective road safety measures, conducting audits, and reducing accident risks.
1. Human Factors (Most Common)
Human errors account for over 90% of crashes globally.
Examples:
• Overspeeding
• Drunk driving
• Fatigue or drowsiness
• Mobile phone usage
• Ignoring traffic signals

8. • Aggressive driving
• Jaywalking by pedestrians
• Lack of helmet/seatbelt use
2. Vehicle-Related Factors
These include faults in the vehicle that affect safety.
Examples:
• Brake failure
• Worn-out tires
• Poor headlight alignment
• Steering system malfunction
• Faulty indicators or lights
3. Roadway and Infrastructure Factors
Poor design or maintenance can increase crash risk.
Examples:
• Sharp curves without warning signs
• Faded lane markings
• Absence of crash barriers
• Inadequate lighting
• Potholes and uneven surfaces
• Lack of pedestrian crossings or footpaths
4. Environmental Factors
Uncontrollable conditions that affect road safety.
Examples:
• Rain causing slippery roads
• Fog or low visibility
• Glare from oncoming traffic at night
• Strong crosswinds (in hilly areas)
• Flooded roads

9. Crash Reduction Capabilities
• Crash reduction capabilities refer to the potential effectiveness of a specific safety
intervention or design improvement in lowering the number and severity of crashes.
• These capabilities are usually quantified through studies or empirical data, which show
how much a particular measure reduces accidents.
• For example, adding roundabouts instead of signalized intersections can reduce severe
crashes due to the elimination of head-on and right-angle collisions.
• Similarly, improving sight distance, lane width, or lighting can significantly cut down
on both frequency and severity of crashes.
• Understanding these capabilities helps engineers prioritize which interventions provide
the best return in terms of safety improvement and cost-effectiveness.
• These values are often expressed in terms of Crash Reduction Factors (CRFs) or
Crash Modification Factors (CMFs) that estimate the percentage decrease in crashes
when a countermeasure is applied.
Crash Countermeasures
• Intersection Design Improvements
One of the most effective countermeasures for reducing crashes is improving
intersection design. Replacing traditional signalized intersections with roundabouts, for
instance, can significantly reduce the likelihood of head-on and right-angle collisions.
Roundabouts slow down traffic and eliminate crossing conflicts, resulting in an
estimated crash reduction of 35% to 70%, depending on the site conditions and traffic
volume.
• Road Geometry Enhancements
Modifying road geometry—such as increasing superelevation on curves or widening
travel lanes—helps reduce run-off-road and lane departure crashes. These
enhancements allow vehicles to better handle curves and maintain lane discipline, thus
preventing vehicles from veering off the road. Such improvements can reduce crashes
by 20% to 40%.
• Speed Management Techniques
To manage vehicle speed, especially in high-risk zones, measures like speed humps,
rumble strips, and narrowed lanes are employed. These features force drivers to reduce
their speed, especially in residential areas or near schools. As a result, both rear-end
collisions and pedestrian-related crashes can be reduced by 25% to 60%.

10. • Pedestrian Safety Measures
Creating safe pedestrian environments is another crucial countermeasure. Installing
zebra crossings, pedestrian signals, and refuge islands allows pedestrians to cross roads
safely. These facilities improve pedestrian visibility and reduce the chance of collisions,
with a crash reduction effectiveness of 30% to 50%.
• Access Management
Limiting the number of access points like driveways, and providing dedicated turning
lanes, can reduce conflicts between through traffic and turning vehicles. This strategy
helps in decreasing side-swipe and angle collisions at access points and intersections,
leading to a crash reduction of around 20% to 40%.
• Shoulder Improvements
Widened or paved shoulders provide recovery space for errant vehicles, reducing the
chance of run-off-road crashes. These shoulders can also accommodate stopped
vehicles and bicycles, enhancing overall road safety. Shoulder improvements are
known to reduce crash frequency by approximately 15% to 35%.
• Lighting Enhancements
Installing proper street lighting, especially at intersections and pedestrian crossings,
improves nighttime visibility and reduces crash risk in low-light conditions. Effective
lighting not only helps drivers detect hazards earlier but also deters risky behavior,
contributing to a 10% to 35% reduction in nighttime crashes.
• Barrier Installations
The use of median barriers and guardrails prevents vehicles from crossing into
oncoming traffic or off-road areas. These safety installations are particularly useful on
highways and hilly terrains and help prevent head-on collisions and run-off-road
incidents. Crash reduction from such barriers ranges from 20% to 45%.
• Traffic Signal Upgrades
Enhancing traffic signals by improving their visibility, adjusting signal timing, or
adding countdown timers can reduce red-light running and rear-end crashes. These
upgrades improve driver compliance and awareness, achieving a 10% to 30% crash
reduction in signal-controlled areas.
• Enforcement and Awareness Campaigns
Behavioral interventions such as speed enforcement cameras, Driving Under the
Influence (DUI) checkpoints, and public awareness campaigns target the human factor

11. in crash occurrences. These efforts lead to safer driving practices and have shown to
reduce various types of crashes by 10% to 40%, depending on enforcement intensity
and public compliance.
Effectiveness of Safety Design Features
Safety Design Features are physical and geometric elements of a roadway planned and
implemented to enhance safety, reduce crash probability, and minimize severity if crashes
occur.
Effectiveness refers to how well these features actually perform in real-world conditions in
achieving their intended safety benefits.
Common Safety Design Features & Their Effectiveness
1. Clear Sight Distance
Clear sight distance is a critical design feature that ensures drivers have an unobstructed view
of the road ahead, including any potential hazards, signals, or curves. This visual clarity enables
drivers to detect and respond to road conditions more effectively, thereby reducing the chances
of sudden braking or abrupt maneuvers. As a result, it significantly minimizes surprise elements
on the road and improves the reaction time of drivers, leading to fewer collisions.
2. Superelevation on Curves
Superelevation refers to the banking of road curves, where the outer edge of the road is elevated
compared to the inner edge. This design helps balance the lateral forces acting on a moving
vehicle during turns, reducing the risk of vehicles skidding outward or overturning. This is
especially effective on highways and hilly terrain where sharp curves are common. By
maintaining vehicle stability, superelevation greatly enhances safety on curved sections of
roads.
3. Median Barriers
Median barriers are structures placed between opposing lanes of traffic on divided roads to
prevent vehicles from crossing over into oncoming traffic. They serve as a physical barrier that
absorbs and redirects vehicle impact, preventing head-on collisions — which are often the most
fatal types of accidents. Median barriers are particularly effective on high-speed highways
where vehicle separation is crucial for safety.

12. 4. Road Shoulders
Road shoulders provide an emergency stopping or recovery zone for vehicles that veer off the
travel lane. They act as a buffer area, giving drivers space to regain control or park during
mechanical failure or emergencies. Well-designed shoulders prevent run-off-road crashes and
offer a safe zone for breakdowns or accident response vehicles, thereby improving roadside
safety.
5. Guardrails / Crash Barriers
Guardrails and crash barriers are installed along roadsides with steep slopes, sharp curves,
bridges, or embankments. They are designed to absorb impact and redirect errant vehicles back
onto the road, preventing them from plunging into hazardous areas. These barriers are highly
effective in reducing the severity of off-road collisions and preventing fatalities in situations
where a vehicle might otherwise overturn or fall off elevated terrain.
6. Speed Calming Devices
Speed calming devices such as speed humps, rumble strips, and chicanes are introduced in
accident-prone or high-pedestrian areas to reduce vehicle speeds. By forcing drivers to slow
down, these features help prevent high-speed crashes and reduce the risk to pedestrians. Such
measures are especially useful in school zones, residential neighbourhoods, and intersections
where sudden stops may be needed.
7. Pedestrian Crossings / Refuge Islands
These design features ensure that pedestrians have designated, visible, and safe places to cross
roads. Refuge islands in the median allow pedestrians to pause safely while crossing multi-lane
roads. These features reduce pedestrian crashes by separating pedestrian movement from
vehicle flow and improving visibility and predictability for both users.
8. Road Markings and Signs
Road markings and signs are vital for communicating essential information to road users.
Markings indicate lane divisions, pedestrian crossings, speed limits, and directions, while signs
alert drivers to hazards, curves, intersections, or changes in road conditions. These visual cues
enhance driver awareness, promote lane discipline, and contribute to safer navigation,
especially for unfamiliar drivers.
9. Street Lighting
Street lighting improves visibility during night-time or low-light conditions. It helps drivers
identify road users, hazards, curves, and signs more clearly at night. Proper illumination also

13. enhances pedestrian safety and discourages crimes. Effective street lighting reduces night-time
crashes significantly by increasing visibility and reducing driver stress and errors.
Accident Reconstruction
Accident reconstruction is the scientific process of recreating a road crash to understand
exactly what happened, how it happened, and why. Experts collect data and apply physics and
engineering knowledge to reconstruct the events before, during, and after a collision.
Importance
It helps answer important questions:
• What were the vehicle speeds before the crash?
• Which vehicle or person was at fault?
• Were the road conditions, weather, or vehicle defects responsible?
This is especially important in legal cases, insurance investigations, and for government
agencies to improve road safety.
Steps Involved in Accident Reconstruction
1. Site Inspection
This is the first and most important step. Investigators visit the crash scene as early as possible
to observe the actual road and environmental conditions. They look for signs like broken glass,
skid marks, damaged road barriers, or anything unusual. A timely visit ensures the evidence is
not disturbed by traffic or weather.
2. Collecting Evidence
At the site, various physical clues are gathered. This includes:
• Skid marks on the road (which indicate sudden braking),
• Vehicle debris (like broken parts),
• Damage to vehicles,
• The final position of the vehicles involved.
• These clues help recreate how the vehicles moved and collided.
3. Photographs and Measurements
Investigators take high-resolution photographs from multiple angles. Accurate measurements
are taken of distances between objects, road width, vehicle positions, and marks on the road.
These measurements are later used to prepare scaled drawings or diagrams of the accident
scene.

14. 4. Vehicle Data Analysis
Many modern vehicles have built-in sensors and Event Data Recorders (EDRs), like black
boxes in airplanes. These devices record details like speed, braking force, steering angle, and
even seatbelt usage just before the crash. This digital information gives insight into the driver's
actions and vehicle behavior before the collision.
5. Computer Simulations
Using the collected data, advanced software tools simulate the crash virtually in 2D or 3D.
These simulations help investigators visualize how the accident happened, including speed,
angle of impact, and the sequence of events. It is often used in court cases or safety reports.
Example:
If two vehicles collide at a junction, and both claim the green signal — a reconstruction expert
can measure skid marks, damage direction, and use CCTV footage to recreate the sequence and
determine who is actually at fault.
Tools & Technologies
• Total Station & 3D Laser Scanner: For precise mapping of crash scenes, skid marks,
and roadway geometry.
• Crash Simulation Software (e.g., PC-Crash, HVE): Used to recreate and analyse vehicle
trajectories, speeds, and collision severity.
o PC-Crash: A physics-based 3-D program that models vehicle motion, impact
speed, and deformation.
o HVE (Human-Vehicle-Environment): A high-fidelity simulation platform
modelling driver input, vehicle dynamics, and environmental conditions
(modules like EDSMAC4 & SIMON).
• Event Data Recorder (EDR): Vehicle “black-box” that records pre-impact speed,
braking, throttle, and steering data.
• Drones / Photogrammetry: Capture aerial images or videos and convert them into
accurate 3-D models of the crash site for visualization and analysis.

15. Condition Diagram
A condition diagram is a top-down (map view) sketch of the accident location. It shows all
fixed physical features of the road and surrounding environment as they were at the time of the
crash.
It is not about the accident itself, but about the road's condition, layout, and surroundings that
may have contributed to the crash.
Condition Diagram include
• Number of lanes and road width
• Direction of traffic flow
• Traffic signals and signboards
• Trees, poles, medians, and footpaths
• Location of speed breakers, curves, potholes, or intersections
• Lighting conditions and road surface
Condition Diagram helps engineers or investigators understand the safety condition of the road
and its surroundings, even if the accident has already been cleared from the scene. It forms the
base to decide if a design change or maintenance is required.
Example:
If a crash happens near a curve with a hidden stop sign behind a tree, the condition diagram
helps visualize the problem: the sign wasn't visible. Based on this, the tree can be cut, or the
sign moved.

16. Collision Diagram
A collision diagram is a visual chart that shows where and how different accidents happened at
a specific location — like an intersection or stretch of road — over a period (e.g., last 1 year).
It shows the direction of vehicles, collision points, and type of crashes.
Symbols and patterns:
• Arrows for vehicle direction
• X marks for crash points
• Different symbols for types of crashes (rear-end, head-on, pedestrian, side-impact)
Each accident is plotted with a short note: date, time, weather, vehicle type, etc.
Importance
By looking at several plotted crashes, engineers can see patterns:
• Do most crashes involve right turns?
• Are pedestrians often hit while crossing from one side?
• Are crashes more frequent at night?
This helps authorities decide where and what kind of improvements or enforcement are needed.
Example:
At a busy T-junction, if 6 crashes are rear-end type, a collision diagram helps conclude that
signal timing or signage might be poor. Engineers can then improve signage or add speed
control.

18. Additional topics
Common Road Safety KPIs
KPIs are generally grouped into three levels: outcome, output, and process indicators.
A. Outcome Indicators (Safety Results)
These measure the final results of safety efforts—injuries and fatalities.
• Fatality Rate (per 100,000 population) – reflects overall road safety in a country or
region.
• Fatalities per 10,000 vehicles / per 100 million vehicle-km – standardizes exposure to
travel.
• Serious and Minor Injury Rates – indicate crash severity trends.
• Crash Frequency & Severity Index – combines accident count and injury intensity.
B. Output Indicators (System Performance)
These relate to safety conditions or behaviors influencing crash risk.
• Seat-belt / Helmet Wearing Rate – measures user compliance with protective laws.
• Speed Compliance Rate – proportion of vehicles adhering to posted speed limits.
• Percentage of Alcohol-related Crashes – gauges driver behavior and enforcement
effectiveness.
• Share of Safer Roads (as per IRC/IRC-SP safety ratings) – tracks engineering
improvements.
C. Process Indicators (Implementation & Management)
These reflect institutional effort and resource commitment.
• Budget allocation for road safety (%)
• Number of safety audits conducted per year
• Training programs / awareness campaigns implemented
• Emergency response time and trauma-care coverage

RSAs are performed during different phases:
Stage Description Purpose
Planning Stage Before the road is designed
Ensure the selected
alignment is safe
Design Stage
During or after the drawings
are ready
Detect unsafe design features
early

19. Construction Stage
When the road is under
construction
Identify issues like poor
signage, slope, curves
Pre-opening (Pre-opening
RSA)
Before opening the road to
traffic
Ensure safety before vehicles
start using it
Post-opening (Operational
Stage)
After the road is opened
Identify actual usage issues
or unexpected conflicts
After Crashes (Reactive
Audit)
If frequent crashes are
reported
Analyze crash causes,
recommend retrofitting

Safety Design Features & Their Effectiveness For PPT (Additional information)
Design Feature Purpose Safety Benefit
Clear Sight Distance
Ensure visibility of hazards,
signals
Reduces surprise elements;
improves reaction time
Superelevation on curves
Balances lateral force on
vehicles
Prevents skidding or
overturning on curves
Median Barriers Separate opposing lanes Reduces head-on collisions
Road Shoulders Emergency recovery space
Prevents run -off-road
crashes
Guardrails / Crash
barriers
Protect vehicles from steep
slopes
Prevents fatalities in off-road
collisions
Speed Calming Devices
(e.g., speed humps, rumble
strips)
Reduce vehicle speed in
risky zones
Reduces crash severity and
pedestrian risk
Pedestrian Crossings /
Refuge Islands
Safe walking paths and
crossing support
Reduces pedestrian crashes
Road Markings and Signs
Provide visual guidance and
alerts
Enhances driver awareness
and lane discipline
Street Lighting Illuminates road at night Reduces night-time crashes

20. Crash Countermeasures For PPT (Additional information)
Intervention Type Example
Crash Type
Reduced
Estimated Crash
Reduction
Intersection Design
Improvement
Roundabouts
replacing signalized
junctions
Head-on, right-angle 35–70%
Road Geometry
Enhancements
Superelevation,
widened lanes
Run-off-road, lane
departure
20–40%
Speed Management
Speed humps,
rumble strips
Rear-end, pedestrian 25–60%
Pedestrian Safety
Measures
Zebra crossings,
pedestrian refuge
islands
Pedestrian crashes 30–50%
Access
Management
Limiting driveways,
dedicated turning
lanes
Side-swipe, angle
crashes
20–40%
Shoulder
Improvement
Paved or widened
shoulders
Run-off-road crashes 15–35%
Lighting
Enhancement
Streetlights in dark
zones
Night-time crashes 10–35%
Barrier Installation
Median barriers,
guardrails
Head-on, off-road 20–45%
Traffic Signal
Upgrades
Improved visibility,
timing, countdown
timers
Rear-end, red-light
violations
10–30%
Enforcement &
Awareness
Speed cameras,
drink-driving
campaigns
Various crash types
(behavioral)
10–40%