Do you have to or want to draw a sketch of the traffic accident?
If yes, AccidentSketch will be a nice tool to help you do the job.
AccidentSketch is a free online service from which you can draw traffic accident sketches easily. You do not need to register, and since nearly all the traffic accident objects ( such as roads, cars, lights, etc) are ready in the library, you just need to move and click the mouse, drag and drop the related objects, draw and add notes to indicate important factors.
There are 2 videos on the homepage, which will help you learn how to draw a traffic accident sketch. And the finished sketch can be downloaded as a PDF file in two pages with all the elements you draw and add.
I came across AccidentSketch from Makeuseof, which you can check out for more details.