Environmental regulations (ER) can support or dissuade the reduction of carbon emissions. However, there are limited studies on the impact of ER on carbon emissions for the transportation infrastructure. Using provincial panel data from China for the period 2001–2017, this study measures how ER can affect the carbon emissions efficiency (CEE) of transportation infrastructure. The study uses Hansen's panel threshold model to analyze current thresholds of ER on CEE. The results show that (1) China's transportation infrastructure during 2001–2017 experienced a 10.15% decrease of CEE; (2) there are significant heterogeneities across the regions of China regarding CEE; (3) ER produces some CEE threshold effects in China's current transportation infrastructure. This study proposes alternative evaluation methods and theoretical frameworks for dynamically measuring the CEE of transportation infrastructure, and provides governments with improved criteria to design effective environmental policies.