Accident Speed Calculator

Calculate the velocity of vehicle in traffic accidents from brake traces on road

The app was developed by a scientist many years of criminal expertise from vehicle speed brake marks left at the scene of traffic accidents.

During the investigation of road traffic accidents we see the scene examination officers often measured length brake marks left at the scene. The goal is to calculate the velocity of the vehicle at the time of the accident in order to find the error. The determination of the velocity of the vehicle at the time of the accident to help find the causes of traffic accidents there. However for calculation requires you to have knowledge of mechanics. To be able to calculate quickly at the scene is very difficult. As an appraiser mechanics working at the Technical Chamber of Criminal - Police Vinh Phuc province has done a lot of mechanical services related traffic accidents. The formulas and algorithms to calculate the velocity of vehicles based on the laws of mechanics and very complex experiment of criminal science. I gave the algorithms, formulas into their applications in order to help investigators, people are not assessors are able to calculate the velocity of the vehicle.

This application allows you to determine the velocity of the vehicle through the length of the measured brake marks at the scene. - The problem here is self-braking and stop (in equation 1 is only the braking force and the drag uphill or downhill balance with inertial force when braking), so this formula applies only when the vehicle is not being crashing into obstacles.

- Vehicles must stop v = 0, this formula applies only when the car stopped completely at the end of trace brake (not working on the sidewalk, down the field, flip ...). Where the car did not stop at the end of the brake marks or stains from the brake a little certain about the automobile velocity is calculated using the formula above is less than the real speed the allowable limit may still be charged for any service requirements of the investigation.

- Coefficient of automobile wheels grip the road surface in addition to depending on the type of road and surface conditions depends largely on the degree of wheel slip relative to the road surface during braking. In the above problem, the wheel grip factor is determined by experiment when the wheel is in motion braked quite hard (pears 100% slip).

- Avoid confusion between braking distance and brake drag trace lengths on the road.

Indeed when car moving on the road the driver apply the brakes when the car strictly from start braking until the vehicle stopped can be divided into 03 stages as follows.

Stage 1 from the brake pedal to the brake force, or this is the time delay of the brake (by itinerary free of brake pedal, the trailers of the driving parts, latency of gas compressed or fluid in the brakes) brake larger latency gas hydraulic brakes.

Stage 2 of the brake force to the left brake marks on the pavement.

Stage 3 since the wound dragged until the car stops. When measured by the above method we just calculate the velocity of cars at this stage so the velocity is smaller at the time of driver starts braking.