In order to quantify the effects of congestion on vehicle operating costs, it is necessary to model not only the speed-flow effects but to also model the variation in speeds. This paper presents a review of such a model developed to date that will enable the prediction of the costs of congestion. The paper also presents an overview of future research aimed at refining the current model form. Other analyses indicate that the true cost of congestion may be underestimated by as much as 30 per cent for passenger cars when accounting solely for the speed-flow effects. Given the limited annual expenditure on roads, it is important to have a model capable of simply, yet accurately, quantifying the cost of congestion to ensure a fair distribution of funds is observed. (A)
Samenvatting