Effect of Interactions between Vehicles and Mid-Block Crosswalks on Traffic Flow and CO2 Emission

Unsignalized mid-block raised crosswalks have been adopted as inclusive transport strategies, providing humps to reduce vehicles' speed to promote drivers to yield to pedestrians. The interaction between vehicles and pedestrians can induce local jams that can merge to become a gridlock. The purpose of this paper is to investigate the interaction between vehicles and the mid-block raised crosswalk, analyzing its effects on traffic flow, instantaneous CO2 emissions, and energy dissipation. A pedestrian-vehicle cellular automata model was developed, where a single-lane road with a mid-block raised crosswalk is considered. The lane boundaries were controlled with the injections rate (alpha) and extraction rate (beta), while the pedestrians' entrance was controlled with the rate (alpha p). The system's phase diagram was constructed, identifying four phases: maximum current, jamming, congestion, and gridlock. All observed phase transitions are of the second order. The transition from maximum current (or jamming) phase to gridlock phase is not noticed. Moreover, since the crosswalk is a bottleneck, the gridlock phase takes place when the pedestrians' influx exceeds a critical value (alpha p > 0.8). The study also revealed that the crosswalk is the main precursor of energy dissipation and CO2 emissions, whose major effects are observed during the jamming phase.