IRTE

Related terms

Coefficient of Kinetic Friction (Mu)

The dimensionless ratio of the sliding friction force to the normal force between a tyre and the road; typically 0.55-0.70 for dry...

Coefficient of Restitution (E)

The ratio of the relative velocity of separation to the relative velocity of approach in a collision; e = 0 for perfectly...

Daubert Standard

The US federal evidentiary standard (Daubert v. Merrell Dow Pharmaceuticals, 1993) requiring that expert testimony be based on scientifically valid methods with...

Energy-Equivalent Speed (EES / Delta-V)

The SAE J2080 metric quantifying the kinetic energy absorbed by vehicle crush deformation, expressed as the speed change equivalent; used in the...

Event Data Recorder (EDR)

An onboard module that records pre-crash vehicle kinematics (speed, throttle, brake, steering) in the seconds before airbag deployment; governed by SAE J1698...

Head-Throw Distance (HTD)

The horizontal distance from the vehicle's front bumper contact zone to the final rest position of the pedestrian's head; used in the...

Momentum Conservation

In the absence of external horizontal impulses, the total linear momentum of a two-vehicle collision system (sum of mass times velocity for...

PC-Crash

Accident reconstruction simulation software (Steffan and Moser, Austria) that models vehicle dynamics, pedestrian multibody kinematics, and collision geometry; validated against crash-test data...

SAE J1739

Society of Automotive Engineers standard for traffic-accident reconstruction covering momentum, skid, and crush-energy methods; the primary scientific-community reference for admissibility arguments in...

Skid-Mark Formula

v = sqrt(2 mu g d), where v is the pre-skid speed (m/s), mu is the coefficient of kinetic friction between tyre...

Yaw Mark

A curved, striated tyre impression produced when a vehicle slides at an angle to its direction of travel during a steered or...

Explained in

• Accident Reconstruction Physics: Velocity, Momentum and Skid MarksInstitute of Road Traffic Engineers (UK); publishes the Forensic Collision Investigation manual that governs police and expert-witness reconstruction methodolo...