Waiting times for trucks, trains, airplanes and ships in service represent apparent transport system inefficiencies, and measures to reduce these may have the potential to abate transport GHG emissions. In international shipping, transportation researchers have pointed out that reduced waiting time in association with port calls holds such promise. We explore the potential for GHG abatement through port call optimization, focusing on crews and their employers - the shipping companies. Adding new empirical evidence to the transportation literature, we confirm the existence of idle time during port calls, and go beyond this in describing the causes for it. We show how several port stakeholders, including government officials, limit the crews’ and shipping companies’ room for maneuver in relation to port calls. We also show why the process of reducing waiting time in shipping is more complex than that for onshore transport modes, where real-time traffic information guides drivers’ route choices, and reduces congestion and waiting time. Our findings have implications for both policy makers and transportation research.

卡车，火车，飞机和轮船在役的等待时间代表了运输系统明显的低效率，而减少这些效率的措施可能会减轻运输温室气体的排放。在国际航运中，运输研究人员指出，与港口停靠相关的减少等待时间具有这样的希望。我们通过优化港口呼叫来探索减少温室气体的潜力，重点关注船员及其雇主（船运公司）。在运输文献中增加了新的经验证据，我们确认了港口停靠期间存在闲置时间，并在描述其原因时超越了此时间。我们展示了包括政府官员在内的几个港口利益相关者如何限制船员和船运公司在港口停靠方面的回旋余地。我们还说明了为什么减少运输中等待时间的过程比陆上运输模式中的过程要复杂得多，在陆上运输模式中，实时交通信息可指导驾驶员的路线选择，并减少拥堵和等待时间。我们的发现对政策制定者和运输研究均具有影响。