## Distance-Time-Velocity Diagrams in order to analyse and reconstruct the traffic accident

If the circumstances of a traffic accident stay controvertible between each party, an accident investigator is getting involved for the clarification, in order to calculate in the context of a crash analysis the velocity at the time of the impact with the help of the connecting facts that are available like skid marks, fluid marks, contact match points, pieces of the vehicle's bodywork and glass splinters that got thrown around, damages of the vehicle, characteristics of the road, range of sight etc.

However the actual event of the accident is still not solved at all. Especially for legal assessment and liability issues it is a lot more interesting, where the vehicles spatio-temporally have been before the impact occurred and which circumstances have led to the crash. Being aware, that the affected vehicle has exceeded the speed limit is not always the crucial parameter for the judgment.

A lot more relevant is the question about where the vehicle has started overtaking and where the oncoming vehicle was at this specific moment. Which range of sight did the driver have in this situation? Could the driver even overtake without putting someone else in danger? Could the crash be avoided by swerving or braking? Did the driver even react appropriately? Could the collision be avoided if the driver has not exceeded the speed limit?

These are all problems in which the involved parties are calculatively connected in a dynamic, which means a spatio-temporal structure.

For an understandable demonstration of the approaching conditions of the vehicles that took part, the time-distance-diagram has turned out to be the best and most established way to do so. All calculations are graphically marked in the diagram with an extra track of motion for each vehicle. Then you can see directly from the diagram no matter when or where you are, where each vehicle was at this time. If one of the vehicles was speeding you can depict the alternative course with driving the permitted speed limit in the time-distance-diagram. Now you can see at first sight if the accident could have been avoided if the speed limit was not exceeded.

These techniques are implemented in the online-tool DTVD. After checking the entries for plausibility the accident investigator or the ambitious lawyer creates a diagram in scale live and online, in order to verify directly and optically the described circumstances. The output is a 1:1 in scale PDF document in a A4, A3, letter, legal, ledger or any other supported format by your printer.

The complete diagram can be imported via DXF-export in all established CAD-programms. The CAD-software displays the road surface, the range of vision and also specific interesting positions of the vehicles to be assigned to the lines of motion of the involved cars.

## The application

Create your distance-time diagram now. For an understandable demonstration of the approaching conditions of the vehicles that took part, the time-distance-diagram has ...