Pedestrian and Bicycle Collision Analysis: Key Investigative Factors

Pedestrian and bicycle collisions are among the most serious and technically complex crash investigations. Unlike vehicle occupants, pedestrians and cyclists have little structural protection, often resulting in severe or fatal injuries even at moderate speeds.

Because of the injury severity and liability implications, these cases require a precise, scientifically grounded approach. At Garrett Forensics, pedestrian and bicycle collision analysis combines engineering principles, human factors evaluation, vehicle data, and scene evidence to determine how and why the crash occurred.

These investigations go far beyond determining impact speed — they examine visibility, perception, reaction time, roadway design, and vehicle dynamics.

 

Understanding the Unique Dynamics of Vulnerable Road Users

Pedestrians and cyclists are classified as vulnerable road users because they lack protective structures such as airbags, crumple zones, or seat belts. As a result:

Injury patterns often provide impact clues

Vehicle damage may be subtle but critical

Throw distance can become an important factor

Visibility conditions frequently play a central role

Each case requires careful reconstruction of pre-impact positioning, movement paths, and environmental conditions.

 

Scene Evidence: The Foundation of Analysis

Accurate reconstruction begins at the scene. Key evidence may include:

Point of impact markings

Tire marks or yaw marks

Debris distribution

Rest positions of the vehicle and pedestrian/bicycle

Roadway geometry

Traffic control devices

Lighting conditions

In pedestrian cases, determining the precise point of impact is critical. Small pieces of evidence — such as fabric transfer, scuff marks, or roadway abrasions — may significantly influence speed and position calculations.

For bicycle collisions, additional documentation includes:

Bicycle frame damage

Wheel deformation

Handlebar rotation

Chain and gear position

Proper documentation ensures measurable data is preserved before it is lost to weather, traffic, or cleanup.

 

Vehicle Damage and Injury Correlation

In pedestrian and cyclist collisions, the interaction between the human body and the vehicle follows predictable biomechanical patterns.

Common passenger vehicle impacts may involve:

Initial bumper contact with the lower extremities

Rotation of the torso onto the hood

Head contact with windshield or A-pillar

Secondary ground contact

Damage to:

Hood leading edge

Windshield glass

A-pillars

Side mirrors

can help determine impact location and vehicle speed range.

In higher-profile vehicles such as SUVs or trucks, impact dynamics may differ, sometimes resulting in forward projection rather than hood wrap.

Injury pattern analysis, when combined with vehicle damage, often provides valuable corroboration of impact mechanics.

 

Speed Analysis and Throw Distance

One of the most common questions in pedestrian and bicycle cases is: How fast was the vehicle traveling?

While throw distance can provide insight, it must be applied carefully. Throw distance is influenced by:

Impact speed

Pedestrian height and weight

Vehicle front-end geometry

Braking at impact

Road surface conditions

Engineers may also incorporate:

Event Data Recorder (EDR) downloads

Momentum analysis

Crush damage evaluation

Surveillance or dash camera footage

No single method should stand alone. Reliable conclusions are formed when multiple analytical approaches align.

Visibility and Line-of-Sight Analysis

 

Visibility is frequently central in pedestrian and cyclist cases.

Key questions include:

Was the pedestrian visible prior to impact?

Were there visual obstructions?

What were the lighting conditions?

Was the cyclist using lights or reflective gear?

Did roadway curvature limit visibility?

Line-of-sight studies may involve:

Nighttime scene inspections

Photometric analysis

Headlight illumination evaluation

3D modeling

Time-distance analysis

In some cases, a driver’s perception-reaction time becomes a major factor in determining avoidability.

 

Human Factors Considerations

Human factors analysis evaluates how drivers perceive and respond to hazards. This may include:

Perception-reaction time

Conspicuity

Attention and distraction

Alcohol or impairment considerations

Expectancy (Was the pedestrian in a crosswalk? Mid-block?)

Understanding whether a driver had sufficient time and distance to perceive and avoid the hazard is often central to liability determinations.

Similarly, cyclist positioning within the lane, hand signaling, or compliance with traffic controls may also be evaluated.

 

Roadway Design, Traffic Engineering, and Environmental Factors

Infrastructure plays a critical role in pedestrian and bicycle safety. Reconstruction may involve analysis of:

Crosswalk placement

Signal timing and phasing

Sight triangles

Roadway lighting

Speed limits

Bike lane markings

Shoulder width

Signage placement and visibility

Poor roadway design, inadequate lighting, improper signal timing, or obstructed signage may contribute directly to the circumstances of a collision.

 

The Role of Traffic Engineering

In many pedestrian and bicycle cases, traffic engineering principles become central to the investigation. This includes evaluating whether the roadway was designed, signed, and controlled in accordance with accepted engineering standards such as the MUTCD (Manual on Uniform Traffic Control Devices) and applicable state or municipal guidelines.

Traffic engineering analysis may examine:

Whether signal timing allowed adequate pedestrian crossing time

Whether sight distance met design standards

Whether warning signage was properly placed and visible

Whether speed limits were appropriate for the roadway environment

Whether traffic calming measures were warranted

Whether bicycle lanes met safety and separation standards

At Garrett Forensics, our team includes expertise in traffic engineering, allowing us to evaluate not only driver behavior but also the design and control of the roadway itself. This multidisciplinary approach ensures that all contributing factors — human, vehicular, and infrastructural — are examined comprehensively.

In certain cases, roadway design deficiencies, improper traffic control devices, or inadequate engineering review may significantly influence liability considerations.

By integrating accident reconstruction with traffic engineering analysis, Garrett Forensics provides a complete evaluation of pedestrian and bicycle collision events.

 

Electronic and Video Evidence

Modern cases increasingly involve digital evidence, including:

Vehicle EDR data

Traffic camera footage

Business surveillance

Residential doorbell cameras

Fleet telematics

Cell phone data

Synchronizing electronic evidence with scene measurements allows engineers to develop accurate timelines and movement paths.

When properly analyzed, this data can significantly strengthen case conclusions.

 

Courtroom Considerations

Pedestrian and bicycle cases often involve severe injuries or fatalities, making clear and scientifically sound analysis essential.

Effective expert reporting should be:

Methodologically transparent

Based on measurable evidence

Supported by accepted engineering principles

Clearly explained for judges and juries

Demonstrative exhibits such as scaled diagrams, time-distance animations, and visibility simulations can make complex engineering concepts understandable in litigation.

 

Why Specialized Analysis Matters

Pedestrian and bicycle collision reconstruction is not simply a scaled-down vehicle case. It requires:

Knowledge of impact biomechanics

Experience in line-of-sight evaluation

Careful interpretation of subtle vehicle damage

Understanding of roadway safety principles

Integration of multiple analytical methods

Early involvement ensures that perishable evidence — both physical and electronic — is preserved.

 

At Garrett Forensics, pedestrian and bicycle collisions are investigated with precision, objectivity, and scientific rigor. When serious injuries are involved, clear answers grounded in engineering matter.