Method
Skid mark speed
Estimate minimum speed from a supported slide-to-stop mark, drag factor, grade, and braking efficiency.
Required inputsMark classification · distance · drag factor · grade · braking efficiency
Primary
Methods that best fit
Supporting input
Roadway drag factor
Establish a case-specific surface value using repeated field measurements.
Required inputsRepeated field tests · test weight · surface condition · grade
Supporting input
Yaw mark radius
Calculate radius from chord and middle-ordinate measurements.
Required inputsChord endpoints · middle ordinate · mark diagram · repeated measurements
Method
Critical speed yaw
Apply radius and drag factor only after classifying the mark as a critical-speed yaw.
Required inputsConfirmed yaw mark · radius · drag factor · cross-slope
Method
Post-impact speed
Work backward from final rest across supported energy-loss segments.
Required inputsImpact area · final rest · path length · surface values · grade
Method
Collision momentum
Combine supported post-impact velocities, directions, and masses.
Required inputsVehicle masses · departure speeds · travel directions · impact geometry
Method
Crush energy
Estimate absorbed energy from measured residual crush and applicable stiffness data.
Required inputsResidual crush profile · stiffness coefficients · overlap · vehicle weight
Method
Delta-V
Relate supported energy and mass data to vehicle velocity change.
Required inputsSupported energy or recorded change · vehicle masses · impact configuration
Corroboration
Restitution
Evaluate rebound when the collision model and evidence support it.
Required inputsApproach and separation velocities · supported coefficient · vehicle masses
Method
Video speed
Use reproducible frames, verified timing, and an independently measured scene distance.
Required inputsSource file · verified frame rate · reproducible frames · measured distance
Method
Time-space diagram
Place observations and movement intervals on a common timeline.
Required inputsCommon time origin · measured paths · positions · supported motion intervals
Supporting input
EDR / CDR event summary
Document event fields, status flags, timing, polarity, and model-specific limitations.
Required inputsOriginal report · event type · time-zero definition · status flags · source limitations
Method
Pedestrian throw
Report the supported Searle range and preserve the method's limitations.
Required inputsImpact location · final rest · throw path · surface condition · secondary contacts
Corroboration
Vault and projection worksheets
Compare level-takeoff, general-vault, slide, bicycle, and object-specific models.
Required inputsLaunch point · landing point · drop height · takeoff angle · post-landing slide
Supporting input
Perception-reaction distance
Separate the available cue and response interval from later braking.
Required inputsAvailable cue · vehicle speed · supported response interval · driver path
Method
Total stopping distance
Combine a supported response interval with physical braking distance.
Required inputsInitial speed · response time · drag factor · grade · braking condition
Method
Hydroplaning screening
Estimate a theoretical threshold while documenting water, tire, load, and pavement evidence.
Required inputsTire pressure · water evidence · tread · load · pavement texture
Method
Scene weather and wet drag
Compare archived conditions with scene evidence and case-specific surface testing.
Required inputsEvent location and time · archived weather · photographs · drainage · surface tests