Train and bus passengers typically don’t spend much time thinking about the doors they pass through when entering such vehicles. But these are highly sophisticated technical systems that automatically open and close the doors on such vehicles, and they are subject to extremely demanding levels of use. They also are a point at which accidents occur for passengers entering or exiting trains and buses – accidents which sometimes result in substantial personal injuries. How is it that such accidents occur? The principal cause is undoubtedly to be found in the in adequacy or indeed the absence of door safety equipment.
Particularly in older vehicles it is frequently the case that there is no equipment for monitoring passenger entry. The rubber profiles on the edges of the doors, which originally were intended to protect passengers’ fingers, have hardened over the years and can no longer fulfil this function. Train cars that are 10 to 15 years old often have a pneumatic pressure wave, a so-called door edge detection process, or an optical boarding safety aid as well as a motor current monitoring system with reversing doors.
The door edge detection system uses a tube running through the hollow chamber of the rubber door profile to detect objects inserted between the two door wings. The signals from this system are transmitted to a evaluating processor unit connected to the door control system. Systems of this type have proven to be very sensitive to changes in temperature and subject to frequent breakdowns. As a result, many transport operators are seeking new alternatives.
At the initiative of the Munich Municipal Transport Authority, the Hübner GmbH and the Mayser Company, both specialists for the development of innovative vehicle components, have conducted an intensive effort to develop and perfect systems for monitoring passenger boarding.
Approximately five years ago, these companies began to develop a highly sensitive, easily installed system to protect against becoming stuck between closing vehicle doors. This effort gave rise to the Gap Detection System (GDS), which has now been fully developed for commercial use.
The relevant testing and safety standards for vehicle doors are the European Standard EN 14752 and the German Standard VDV 111. These standards specify the required door closing process, the closing forces for the door and the prescribed dimensions of a test object (30 x 60 mm).
The GDS is so sensitive that it also can readily detect much smaller objects (such as a child’s foot or the wheel of a baby carriage). This exceeds the current regulatory requirements as well as the capabilities of existing systems. With the GDS, it has been possible to develop “responsive door edges”. Depending on the model and the particular installation, the system reliably detects objects of 5 mm thickness and registers this as door interference. The door opens again automatically; if necessary the vehicle will be braked shortly after start-up if the system is still registering a door interference event.
In the meantime, a large number of transport operators have begun on their own initiative to install this system in vehicles undergoing refurbishment, HU or GU measures. Well-known door manufacturers in the public transport sector have come to see the system as the standard solution for boarding safety equipment.
For outwardly swinging doors, the installation of new door edge profiles is very simple as the electrical safety edge is equipped with a rubber sealing edge. The existing electrical input and output leads that are part of a pneumatic pressure wave system for example can be used in the new GDS system. An evaluating processor unit is installed upstream in the door control system. The door control system and the evaluating processor unit can simply be connected with each other. A software adaptation in the door control system is not necessary.
The Munich Municipal Transport Authority and the Berlin Municipal Transport Authority have had the most extensive experience using the GDS system.
In the near future, the Deutsche Bahn AG will replace the pneumatic pressure wave system used in pressure-sealing doors with the GDS system on high-speed ICE 3 and ICT trains. In addition, modernization and refurbishment plans involving the GDS for door safety are pending for regional trains in Germany and have already been implemented for the double-decker vehicles.
In summary it may be stated that the Gap Detection System offers a
fully developed, easily implemented and economical system for
maximizing passenger safety in connection with vehicle boarding and
deboarding for both rail and bus vehicles. The system has been well
accepted by the market and represents the new standard solution
(requirement profile) in outfitting new vehicles so as to ensure safe
entry and exiting of vehicles.
Dipl.-Ing. Ralf Waibel
HÜBNER GmbH, Kassel