Speed identification problem of traffic accident that

Recently, through different channels (different consulting, traffic police, appeal, the case, communication) reading about traffic accident speed identification of judicial report (opinion). Many people are vehicle speed (or velocity) on the basis of calculation from "GA/T643 - 2006 Typical accident vehicle speed identification". The ministerial standard in many computational methods (formula) is taken from the two book "my car accident Engineering" and "the road traffic accident analysis and reappearance", so a direct reading of "the road traffic accident analysis and reappear" (police officer education publishing house, now the Public Security University Press), "the car accident" and "the road traffic accident analysis and processing" (people traffic Press), direct quotes formula or method in the book in the specific case analysis, and as the appraisal conclusion and present it to the court or police. Some people in the court may directly take out the book as a basis for read, sometimes I don't know who claimed to be my students or cooperate with me. To illustrate this:

Formula and method in the book some universal only exception. The latter is only suitable for certain conditions, a specific vehicle and specific condition, the specific road conditions. The book most formula is the typical real world traffic accident, that is to say, the actual traffic accidents are abstract, removing selection from the main factors, mathematical modeling. But the real world situation is the process of traffic accident theory is applied to the practice of traffic accident.

This requires the forensic examination of traffic accidents are combined with the specific circumstances of the accident, the formula and method. Even if the formula and the method is suitable for the present processing traffic accident, also need to choose the correct parameters, formula conditions, to accord with the actual. Theory, practice and experience (the actual case, books, test data, combined with the experiences of others), the three are indispensable. Of no practical theory correctly, more reasonable, is not used in the actual time and error.

Sometimes with the traffic accident, accident data collected by a group of people sharing, with the use of a formula or algorithm, often have come to a different conclusion phenomenon, its reason is who do not practice, whose result is wrong! Only select the formula and algorithm appropriate, and consistent with the actual, the conclusion is reasonable.

At present, there are traffic accident speed identification are two main problems:

1) select the formula is not reasonable, do not understand the theory origin, namely the original formula. Typical is the use of braking India distance derived velocity formula (including individual wheel braking state of different situations), India and India trailer brake sideslip difference, fallout formula.

2) formula parameter selection and measurement from the actual conditions, such as vehicle and accident and accident (collision and friction coefficient), the adhesion coefficient, the total quality of the bus, car (effective) deformation and position, maximum speed.

In addition, hereby declare: not my autograph or phone confirmation, are not my students and collaborators, which also includes the website I is the expert.