Benefit-cost analyses (BCA) of measures of transport telematics causing small speed changes of traffic flow.

Many ITS and traditional measures concerning the road network and the traffic management cause speed changes. Measures of this kind include among others the change of the speed limit by using variable road signs or their implementation, methods of collecting road tolls, the implementation of traffic signals at road junctions and their regulation, the implementation of navigation tools, etc. On the other hand, many other measures - without or with transport telematics, which reduce or eliminate the congestion - belong also to this category, because their goal is to increase the average traffic speed and decrease the speed variations. The problems connected to the benefit cost analysis of this kind in the ITS projects concern identifying and, especially, quantifying of small changes of the impacts caused by these measures. The impact categories caused by the speed changes include the following items: the level of service (the used time, comfort, driving stress), the reserved and used resources in the transportation (road space, energy and other vehicle operating costs etc.), the traffic safety, the environmental impacts of the transportation (the emissions by components), the equality (the impact distribution between the different road user groups). The normal and traditional way to quantify these impacts is to use coefficients (the average impact value per the traffic product unit [vehicle kilometer]) for each road alternative and multiply them by the traffic product and then to apply the unit prices and finally to obtain the results in monetary terms for the benefit-cost analysis. However, the average coefficients are neither correct nor accurate enough, because the traffic conditions vary from road to road and from one road section to another and from time to time. Especially, in case of small changes in the impacts the traditional method based on only averages does not work. A new, better and more accurate than the traditional approach is needed and presented here. It is Vehicle Motion Simulation based on dynamics and called VEMOSIM.