Cost sharing in passenger transport models: specification, implementation, and impacts
本文质疑客运模型中默认所有成本由司机承担的做法，认为成本分摊会以多种形式发生，并影响需求弹性和汽车占用率。基于丹麦数据，发现若忽略成本分摊，高占用率的长途休闲出行成本弹性和占用率估计会有偏差。
• We provide arguments why cost sharing should be considered in transport models. • If cost sharing is ruled out cost elasticities and car occupancy rates will be biased. • Different econometric specifications are presented and their impact is analyzed. • Significant impacts for longer leisure trips with a high number of occupants. • Observation that most research papers on mode-choice do not consider cost sharing. A common practice in many transport models is to allocate all costs to the car driver meaning that car passengers are essentially free riders. This specification provides an easy way of integrating drivers and passengers and fits well with the general understanding that car drivers rarely trade passenger seats for money. However, in this paper, we question this premise and argue that cost sharing can, and most likely will, take place in a variety of forms different from simple out-off-pocket money exchange. We also stress that from a modelling perspective, this issue is far from irrelevant as it influences not only demand elasticities but also the modelling of car occupancy rates which is one of the key variables when considering congestion, climate impacts, and network utilisation. In the paper we discuss the mechanisms by which costs are shared, consider how this can be operationalised in transport models, and finally, consider the consequences of cost sharing from a transport policy perspective. Based on empirical evidence from Denmark, we find that for trip purposes with high occupancy rates, cost elasticities and occupancy rates tend to be biased if cost sharing is not properly accounted for.