A game-theoretic approach to designing carbon regulations in a duopoly freight transportation market: Road and multimodal road-rail competitive systems.

Since the transportation industry produces remarkable carbon emissions worldwide, governments aim to curb these emissions by implementing different carbon regulations. However, little is known regarding how the heterogeneity of transportation systems should be exploited to design carbon regulations. To fill this research gap, the present article formulates carbon cap-and-trade and carbon offset regulations to reduce total carbon emissions produced by road and multimodal road-rail freight transportation systems (FTSs) in a duopoly market; the latter is regarded as a green, energy-efficient transportation mode. A novel procedure is suggested to allocate initial carbon caps that is a hybrid of both benchmark and grandfathering methods. The procedure allows the government to exploit the energy efficiency of the multimodal system, when targeting a reduction of total carbon. Then, a game-theoretic approach is adopted to implement the mentioned carbon regulations. A government, as a Stackelberg leader, maximizes a social welfare function containing economic, social, and environmental dimensions. Under the cap-and-trade regulation, a Nash bargaining process is proposed to trade carbon permits between the FTSs, as the followers, for updating their initial caps. The equilibrium outputs of the two mentioned carbon regulations and a carbon tax regulation are compared. The findings based on an experimental analysis suggest that the cap-and-trade (carbon offset) is the optimal and energy-efficient regulation from the social (economic or environmental) perspective. In terms of policy implications, our findings indicate that the development of a marketplace infrastructure for trading carbon permits is not justifiable under the economic and environmental perspectives of the government.