Congestion costs.

Author(s)
Buus Kristensen, N. Riff Brems, C. & Sloth, B.
Year
Abstract

When considering infrastructure tolling, the White Paper on European Transport Policy states that tolls should reflect the costs that the road user imposes on society. An important part of these costs originate from congestion. This paper presents a newly developed method to evaluate the congestion costs based on both delays and increased uncertainty in travel time. The congestion costs are quantified for urban roads, arterial roads and motorways. The effects of congestion on travel time are described by distributions of travel time based on observations of traffic intensities and travel times. Distributions are gathered for each of the three different road types. As expected it was found that at low volume/capacity ratios the traveller has a low journey time with little expected variation, whereas at higher volume/capacity ratios the journey time and the expected variation in journey time both increase. With these observed distributions of journey time an optimal planned journey time is derived based on the differences in the traveller's valuation of journey time, early arrival and late arrival. If a traveller has a fixed arrival time they value late arrival three times as highly as journey time or early arrival. The optimal planned journey time is the 75%-fractile of the journey time distribution. In this way the journey time can be split into free flow journey time, expected delay, and unexpected delay and the time components can be evaluated accordingly. Furthermore, the distributions are used to derive marginal costs of congestion including effects of both delays and increased uncertainty in journey time. The marginal costs vary with traffic intensity and thereby by time of day. The preliminary results show no significant marginal costs for traffic intensities below capacity and fast increasing marginal costs when traffic capacity is reached. This corresponds to the theoretical findings regarding marginal costs. For motorways the preliminary results indicate that the marginal costs of congestion in the peak hour amounts to 0.25 Euro/vehicle-km, while the corresponding figures for urban and arterial roads varies from 0.5-1.1 Euro/vehicle-km. For the covering abstract see ITRD E124693.

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Publication

Library number
C 31832 (In: C 31766 CD-ROM) /72 / ITRD E124759
Source

In: Proceedings of the European Transport Conference, Homerton College, Cambridge, 9-11 September 2002, 15 p.

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This publication is one of our other publications, and part of our extensive collection of road safety literature, that also includes the SWOV publications.