A highway design concept based on probabilistic operational reliability

This paper will propose an easy to apply design load concept that treats capacity and traffic flow as random variables. It will show that the traffic flow within a volume class is normally distributed and that its standard deviation changes with the volume to capacity ratio. A new definition of capacity is given and estimated. Given the new capacities reliability is described by the costs of breakdowns which are assessed based on the value of travel time savings. The paper will show how the results can be integrated into a cost-benefit analysis.