A Review on New Design Load Concept for Highway Infrastructures

Abstract

This paper proposes a design load concept that treats capacity and traffic flow as random variables. This contrasts with the n^th hourly volume concept which neglects the highest traffic volumes, which produce a disproportionate share of the social or generalized costs of any facility. It will be shown that the traffic flow is normally distributed within time windows, but varies in the standard deviation depending on the volume to capacity ratio. A new definition of capacity is given and estimated for an example. The method estimates the probabilities of traffic flow being larger than the capacity for any given scenario. This reserve capacity is linked to breakdown probabilities, queue lengths and therefore generalized costs of facility use. These results could easily be integrated into a cost benefit analysis, which systematically focuses on the most expensive situations.