Abstract
This paper presents a new comprehensive method for managing hi-rail vehicle set-on and set-off in a Communications-Based Train Control (CBTC) system using axle counters as a secondary train detection system.
Due to its high performance in terms of headway combined with low required maintenance [1], CBTC is now the preferred technology for metropolitan rapid transit systems around the world. Metropolitan transit lines such as New York City Transit and Toronto Transit Commission are often underground or elevated on a structure and/or are relatively short so maintenance vehicles access work areas only via rail from the yard or a spur track used as storage.
In the past few years, CBTC has started to be deployed on what the industry refers to as commuter rail lines. Commuter rail lines have short distances between stations within the city centers and long distances between stations in suburban areas using at grade tracks running along highways. Therefore, to facilitate maintenance activities, operators of commuter rail lines use hi-rail vehicles that drive on the roads and enter the rail network at specific set-on areas. Examples of CBTC projects on commuter rail lines include Bay Area Rapid Transit, Paris Réseau Express Régional, and Montreal Réseau Express Métropolitain.
The majority of new CBTC systems for commuter rail lines are using axle counters as a secondary means of train detection. The CBTC and axle counter systems have a complex functional interface. Using hi-railers in a CBTC system that relies on axle counters generates challenges for both the CBTC system and axle counters. The method to handle those challenges is the result of collaborative design effort over several years by a transit agency, a CBTC contractor, an axle counter vendor, and numerous consultants.
This work starts by introducing relevant CBTC technology functions. Principles of axle counters, including the need for a reset of axle counter blocks and the different reset methods are described. The challenges resulting from hi-rail set-on and set-off are explained, showing the impact on both the axle counter system and the CBTC train movements. Then, the preferred method for managing the challenges introduced by hi-rail vehicles set-on and set-off are presented. There are two variations depending on whether events arise during revenue service or at night when revenue service is stopped. Other disregarded methods are briefly explained with the reasons why they are not suitable. Finally, the authors provide thoughts on this method and describe the possible improvements.
