Collaborative Merging Behaviors and Their Impacts on Freeway 1 Ramp Operations under Connected Vehicle Environment

46 Under connected vehicle environment, vehicles are able to communicate and exchange detailed 47 information such as speed, acceleration, and position in real time. Such information is important 48 for improving traffic safety. In the meantime, it allows vehicles to collaborate with each other, 49 which may significantly improve traffic operations particularly at intersections and freeway 50 ramps. To assess the potential benefits of collaborative driving behaviors enabled by connected 51 vehicle technologies, this research proposes an optimization-based ramp control strategy and 52 develops a simulation platform using VISSIM, MATLAB, and the Car2X module in VISSIM. In 53 addition to the optimal control strategy, an empirical gradual speed limit control strategy is also 54 proposed. These strategies are evaluated using the developed simulation platform in terms of 55 average speed, average delay time, and throughput and are compared with a benchmark case 56 with no control. The study results indicate that the proposed optimal control strategy can 57 effectively coordinate all merging vehicles at freeway on-ramps and substantially improve safety 58 and efficiency, especially when the freeway traffic is not oversaturated. 59 60