Marginal congestion costs in the case of multi-class traffic: A macroscopic assessment for the Paris Region

- Macroscopic analysis of multi-class reciprocal road congestion in the Paris Region.
- Study using accessible data from household and freight surveys.
- Estimates of time losses for small and large vehicles through econometric analysis.
- Calculation of marginal congestion costs for each types of vehicles.
- Analysis can be transposed to other cases, results are useful for policy evaluation.

Although road congestion caused by freight activities is often pointed-out by researchers and public deciders as a major issue, few studies model time losses at a macroscopic-regional level within a “multi-class traffic” framework. This research proposes such empirical assessment for the Paris region, using a simple method based on individuals' trip durations. We combine information on passengers and commercial transport (to describe road demand) with a GIS describing the stock of infrastructures (road supply) on that territory.According to econometric results, the travel times react differently to the flow of similar and dissimilar vehicles: Cars and vans are more impacted than trucks by the volume of “small” vehicles, whereas “large” vehicles are more affected than cars and vans by the presence of other large vehicles. Our methodology thus highlights varying and reciprocal congestion impacts, which is not common in the literature. We then propose various marginal congestion costs, for various origin-destination pairs, various time periods and various types of vehicles. In particular, we decompose external losses incurred to each category of vehicles by each category of vehicles. These results constitute valuable materials for future appraisals of transport policies in the Paris region.