Is There a Quick Way to Estimate Speed from Photo of Damage to a Car?

[MSI]

Q: I'm looking for a relatively quick way to estimate speed from a photo of damage to a car. Lower speed damage may be a common consideration. My input, a photo. Output, a rough estimate of speed and weight. I imagine the two go hand in hand. This is only to provide a fair idea of the forces involved that created the damage


A: Crash reconstruction from photos only should be a first approximation and/or only as a last resort.

• There were many papers written on the importance of vehicle examination.
  • Particularly in low speed impacts, due to the amount of possible ‘hidden damage’ as in how much were the components of the bumper energy absorbing system engaged?
    See
    • SAE 930211 "Automobile Bumper Behavior in Low-Speed Impacts",
    • SAE 940916 "Characteristics of Specific Automobile Bumpers in Low-Velocity Impacts"
    • SAE 980023 "Speed Change Determination in Low Speed Impacts - A Comparison of Techniques"
    • And other papers and research on the topic
• Secondly there are programs like Photomodeler which include techniques for crush measurement approximations see their website topic:
  • Crush Measurement with PhotoModeler
• And then 3rd there is restitution:
  • In low speed impacts higher restitution acts to reduce the residual damage while increasing the impact speed change
    • Damage Analysis programs do NOT include restitution
  For related topics see:
  • Validation of Damage Analysis in Low Speed Impacts
  • The "No Damage Intercept" of CRASH

You mention: My input, a photo. Output, a rough estimate of speed and weight

• The speed is the only output from a damage analysis
• The weight you need to approximate for each vehicle
  • First find the curb weight, the Canadian vehicle specs is a good source
    • Where can I find the Canadian Vehicle Specifications? CVS2023.3
    Then add in approximations for weight for any occupants and cargo in each vehicle
    And calculate approximate speed
  CRASH and other damage analysis programs are available from several vendors
  (we don’t currently sell any ‘damage analysis only’ programs)

Speed from "only damage analysis" is a rough approximation and particularly in lower speed impacts it is important to examine the vehicle too since photographs can hide damage (and i say plural photographs since a single photograph cannot represent the full extent of damage, you need more than one angle, and again, a photograph won't show what's under the bumper cover?

And as pointed out in the ‘no damage intercept’ above, a simplifying assumption of damage analysis is a ‘no damage intercept’ of approximately 4-5 mph which means most vehicles sitting in a new car showroom have 4-5 mph of impact speed change when in reality they have none.

One additional item in damage analysis is the collision partner: what produced the damage on the vehicle?

• Damage analysis is based on virtual crush coefficients.
  • The crush coefficients are created based on individual cars crashing into non-deformable barriers.
    Cars crashing into other cars are not 'a car into a non-deformable barrier'
    It is a virtual spring into another virtual spring and be sure to include and analyze the damage to BOTH vehicles.

So to summarize (and perhaps add a bit more information)

• Damage analysis is a first approximation technique
  • It is important to look at the two collision partners (pictures of both as a minimum) when trying to determine an approximate impact speed change.
• There are crash tests databases by NHTSA and others
  • Which can be searched by type of collision and include some lower speed crashes
• There is the NHTSA CISS database
  • Which includes a searchable database with documentation on thousands of crashes investigated by NHTSA
    Many have EDR data and many are lower speed crashes
    The database can be searched by vehicle type and impact type
    This is a great information resource particularly for lower speed crashes
• Photographs do not document all the possible damage, particularly in low speed crashes.
  • Damage to the underlying bumper structure (in frontal and rear impacts) may mask some additional information to allow braketing the range of impact speed change for a vehicle