Using data from the Pennsylvania shale gas boom, we find each additional truck on the road increases the number of accidents involving a truck—but, to an even larger extent, the number of car-on-car collisions.
- We examine county-wide changes in accidents as shale gas wells are drilled and estimate that one shale gas well requires 2,800 one-way truck trips for water withdrawal and waste disposal.
- The additional traffic means that each well drilled results in a 1 percent increase in the number of accidents involving a truck and a 0.18 percent increase in non-truck accidents.
- Because there are more cars than trucks on the road, in gross terms, each well drilled results in a larger number of non-truck accidents than truck accidents (.55 per well versus .17 in the county and quarter a well is drilled).
- If an average truck's annual miles driven are concentrated in one zip code, the annual premium of new car insurance enrollees increases by 48 cents.
The presence of a heavy truck on the road can impose an externality if accidents occur that would not have otherwise. We find each additional truck on the road increases the number of accidents involving a truck—but, to an even larger extent, the number of a car-on-car collisions. Our estimates imply two percent of all car-on-car collisions can be attributed to trucks on the road. This negative externality falls on all road users through higher car insurance premiums: one truck, driving for a year in the same zip code, increases the insurance premium of each new enrollee by $0.48/year.