Transmission Range Evaluations for Connected Vehicles at Highway-Rail Grade Crossings

Abstract

This study evaluates the transmission range requirements of Connected Vehicles (CVs) at Highway-Rail Grade Crossings (HRGCs) in terms of safety improvement. The safety improvement of HRGCs is evaluated by using a reliability-based risk analysis that calculates risk of collision for CVs and non-CVs. Trains are assumed to have onboard units that transmit train location and speed information to CVs via vehicle to vehicle communications. The stopping distance and time to collision of a vehicle are the demand functions in reliability-based risk analysis. The demand functions consist of probability density functions of a vehicle's initial speed, perception-reaction time, initial deceleration rate, final speed, and final deceleration rate. Train arrival time depending on the train speed and transmission range is the supply threshold for calculating the CV's risk of collision at passive HRGCs. The transmission range's projected highway distance is the supply threshold for CVs at active HRGCs. After deriving probability density functions of demand functions from the published data, Monte Carlo simulations generate the probabilities or risks that a CV would fail to stop within the transmission range or train arrival time. With the provision of a 600 m transmission range, the risk of collision for the CV is lower than that for the non-CV with a 300 m sight distance to the train at the passive HRGC. The CV's risk of collision is lower than the non-CV's with a 300 m transmission range at active HRGCs. The CV application at HRGCs can improve safety by reducing CVs' risk of collision. A 600 m transmission range is desirable at passive HRGCs. A 300 m transmission is sufficient for CVs at active HRGCs. Overall, a 600 m transmission range is feasible to improve the safety at passive and active HRGCs.

Deployment of Autonomous Trains in Rail Transportation: Current Trends and Existing Challenges

“…A number of studies have been conducted to enhance safety at HRGCs, which would be critical for the development and deployment of the future ATs. Hsu and Jones [132] analyzed the CV transmission range requirements at HRGCs, aiming to improve the overall safety of approaching vehicles and passing trains. The study assumed that the approaching trains had the onboard communication units that transmitted the information regarding the train speed and location to the CVs.…”