On the screen, a vehicle about to collide with a bicycle appears in slow motion. After the crash, the cyclist projects a series of meters until he falls inanimate on the road. It seems that we are talking about a movie, but the worst is that it is about reality. We are in front of a graphic reconstruction of a traffic accident where the authenticity is shocking. It has fulfilled its purpose. Well precisely that is what it is, any simulation and reconstruction of an accident are intended to clarify it in the most viable way, using the most comprehensive and accurate techniques possible.

Of course, each case has its specific way of acting, but in all of them, the most important thing is to obtain all the possible data because the signs that are not initially found will be lost forever. This is because the scenarios are easily contaminated and the tests devalued. For this reason, experts are accustomed to filming the entire scene of the case from different perspectives and angles, photographing the smallest details with various illuminations, collecting and recording the samples to try not to lose any detail.

This way of working serves to facilitate the work of the experts, together with the appearance of the virtual analysis of scenarios, where among other things you can do reconstructions and simulations of 3D scenes, particularly useful in traffic accidents. With programs of reconstruction, simulation, and animation (the latter lacks scientific rigor), experts can see how a certain accident occurred before a judge. These computer programs take into account the variables that affect the person, the vehicles and the environment, making them extremely real.

There are several reconstruction and simulation programs but we will only talk about three. The HVE, the PC Crash, and the Reconstructor, since they are used by the police and detectives since they believe more in their reliability.

• HVE (Human Vehicle Environment) - can be used for simulation and reconstruction of traffic accidents, since it allows the creation of three-dimensional models of vehicles, people and surroundings, studying their interactions. 

• PC Crash - is a collision and trajectory simulation tool that allows accurate analysis of a wide variety of motor vehicle collisions and other incidents. 

• Reconstructor - is a program for the reconstruction and animation of accidents that, together with the 3D Studio Max, makes it possible to see the sequence of the accident in three dimensions.

All these computer programs allow us to observe the environment of an accident so that both the time and the distance of the facts are not a gap to investigate the causes and possible culprits of an accident.