Improvement of traffic safety by cooperative vehicularapplications is one of the most promising benefits of vehicularad hoc networks (VANETs). However, to properly develop suchapplications, the influence of different driving parameters on theevent of vehicle collision must be assessed at an early design stage.In this paper, we derive a stochastic model for the number ofaccidents in a platoon of vehicles equipped with a warning collisionnotification system, which is able to inform all the vehicles aboutan emergency event. In fact, the assumption of communicationsbeing used is key to simplify the derivation of a stochastic model.The model enables the computation of the average number ofcollisions that occur in the platoon, the probabilities of the differentways in which the collisions may take place, as well as otherstatistics of interest. Although an exponential distribution has beenused for the traffic density, it is also valid for different probabilitydistributions for traffic densities, as well as for other significantparameters of the model. Moreover, the actual communicationsystem employed is independent of the model since it is abstractedby a message delay variable, which allows it to be used to evaluatedifferent communication technologies. We validate the proposedmodel with Monte Carlo simulations. With this model, one canquickly evaluate numerically the influence of different model parameters(vehicle density, velocities, decelerations, and delays) on thecollision process and draw conclusions that shed relevant guidelinesfor the design of vehicular communication systems, as wellas chain collision avoidance applications. Illustrative examples ofapplication are provided, although a systematic characterizationand evaluation of different scenarios is left as future work.
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