The effects of highway tolls on private business activity—results from a natural experiment
利用葡萄牙高速公路因主权债务危机意外收费的自然实验，研究发现收费显著减少了沿线城市的私营企业数量和就业，且影响随距离和行业而异。
Abstract The article studies the impact of a switch from free to charged highway provision on firm numbers and private sector employment in a panel of Portuguese municipalities covering the period 2007–2013. It exploits the fact that tolls on certain highways in Portugal were unexpectedly introduced in reaction to the sovereign debt crisis to establish causality. Findings suggest that the price of highway tolls in terms of forgone employment and firm formation may be substantial. Comprehensive analyses of effect heterogeneity reveal that the effects differ across municipalities, sectors and firm size classes. The negative effects of highway tolls are strongest in the municipalities traversed by the newly tolled highways and seem to decrease with distance from these highways, whereas distance to Lisbon aggravates the negative effects of the tolls. We also find that larger firms and manufacturing firms are more strongly affected by the tolls than smaller firms and firms in the service sector and that the negative effect on firm numbers is strongest immediately after the introduction of the tolls, whereas the negative effect on employment increases with the duration of the treatment.