Although doors and door controls make up only 2 to 3 percent of the cost of passenger rail cars, it is estimated that they are responsible for as much as 25 percent of the maintenance costs. In Europe and Asia, localized passenger door controls are the norm; in North America, operator/conductor controlled doors are much more common, although passenger controls are commonly incorporated into door systems on light rail (tram) type vehicles and some commuter cars.
The majority of new light rail systems in North America have passenger-actuated doors, which increase comfort inside the car and may reduce wear and tear on the door system. However, at busy stations, where the use of all doors is generally required, operators tend to override passenger controls and open and close all doors at once, avoiding any last minute opening and closing by passengers.
The primary traditional justifications for localized passenger controls almost always involve HVAC/climate benefits. When passengers have control of the doors, the cars tend to retain more heating or cooling since passengers can operate doors faster, offering accessibility that is available as needed. A direct HVAC benefit is the ability to size HVAC units that are smaller, since efficiency is increased and BTU load is decreased. There can also be an impact on dwell time. On some European lines where doors don't automatically open if not activated by passengers, waiting times have been reduced.
Whether localized passenger door controls affect Mean-Time-Between-Failure (MTBF) or Mean-Time-To-Failure (MTTF) currently seems to be unknown. As railway lines investigate semi-automatic, driverless, and unattended train operations, the responsibility for door control even in North America may come to rest squarely on the passengers' shoulders or a remote operations center.
Regardless of who is controlling the doors, the critical elements include safety, ease-of-operation, integration with existing control systems, accessibility for all passengers, and reduction of the potential for human error. This article looks at the latest trends and requirements in passenger access as they relate to door systems, with a mention of other passenger access issues related to toilet compartments and passenger alert systems.
Door control systems on passenger rail cars have developed beyond simple open and close buttons. These control systems provide the most common area for passenger interaction with the rail car. The design of passenger access systems for rail involves all the aspects of a Human Machine Interface (HMI) System:
- Careful consideration of human factors;
- Ergonomic criteria, including Americans with Disabilities Act (ADA) and TSI-PRM requirements;
- Interoperability throughout a rail fleet;
- Clear and simple presentation of critical data;
- Clear and consistent feedback to the passenger, both audible and visual;
- Integration of industry and federal guidelines and best practices.
HMI Systems provide the controls by which a user operates a machine, system or instrument. For passenger access in a rail car, the system to be operated is usually a door control. Door controls in North America are usually automatically controlled and operate all at once, triggered from a master door controller found in the operator compartment. As stated previously, local passenger door control is primarily found in light rail or streetcar installations.
According to the latest APTA Standards Development Program Rail Standard (APTA SS-M-18-10, Approved February 11, 2011), passenger access for powered exterior side doors on passenger cars incorporates the minimum design requirements necessary for doors that provide:
- Entrance and exit for normal passenger boarding and detraining;
- Emergency egress/access path.