A heavy truck imposes an externality if its presence causes traffic accidents for which it is not held liable. We estimate the increase in accidents that occur when a truck is added to a road using quasi-experimental variation in truck routes of connecting shale gas wells in Pennsylvania. We find evidence that adding a truck to a road is relatively safe for the truck itself, but less so for other cars on the road: an additional truck leads to an increase in the number of car-only accidents. However, these additional accidents are not more severe. Finally, we find suggestive evidence that the accident externality of trucking reverberates to even more road users through higher car insurance premiums.

如果重型卡车的存在引起交通事故，而该卡车不承担责任，则该卡车将承担外部性。我们使用宾夕法尼亚州连接页岩气井的卡车路线中的准实验变化估算了将卡车添加到道路上时发生的事故增加。我们发现有证据表明，在道路上增加卡车对卡车本身而言相对安全，但对道路上的其他车辆而言则相对较不安全：增加卡车会导致纯汽车事故次数增加。但是，这些额外的事故并不严重。最后，我们发现了有启发性的证据，表明卡车运输的事故外部性通过更高的汽车保险费回荡给更多的道路使用者。