New design concepts for transport infrastructures

Abstract

The commonly used techniques for measuring capacity are mainly based on evolutionary concepts. These have been established due to the lack of detailed traffic information and limited capacity to evaluate the data. This situation has changed but is still far from the optimal state of full information, which surely never will be achieved. Though having detailed information about traffic flow, mean values are widely used to design transport infrastructures. The Swiss Norm provides factors to calculate hourly values from the average annual daily traffic by neglecting the variance. This could easily lead to wrong assumptions. If non-linear travel-time functions are used e. g. in assignment models, this variance must be included, for a calculation with a mean traffic flow underestimates the travel times. Other engineering sciences offer modern techniques to build risk sensitive models. The resistance and load are handled as random values and no longer as mean values. A concept similar to the Euro Code is applied to estimate the breakdown probability of roads depending on the traffic volume. This could be used as a proxy for the quality of service and for a detailed cost benefit analysis.