Press Release
The opening and closing of automatic door and entry systems in local and long-distance public transport vehicles occurs hundreds of thousands of times each day just in Germany. This operation is a part of our everyday life that we hardly think about for a moment -- but perhaps we should.
Neither in Germany nor in other countries around the world is there a local, private or state-run public transport company or operator that hasn’t had to deal with self-closing vehicle doors that catch passengers between the door leaves. The majority of these companies have had to confront this issue repeatedly.
Frequently these incidents have resulted in serious accidents, incidents that are by no means trifling occurrences and have involved severe personal injury and even death.
Why do such incidents occur? Broadly stated, the cause is door monitoring systems that either simply do not exist, provide limited functionality or do not work properly.
This is particularly the case for older vehicles which frequently do not possess a detection system or have rubber finger protection profiles on the door edges that have become so hard after 15 to 20 years of use that they no longer provide any protective function.
Rail vehicles mainly of more recent models are often equipped with a pneumatic pressure wave, an optical boarding detection system or so-called motor current monitoring systems with reversing doors.
The pneumatic pressure wave system has been in use some 20 years for the detection of objects stuck between the door leaves. The system functions using a hollow chamber that runs through the rubber door profile and sends a signal to an electronic evaluating unit when an object is detected between the doors. The evaluating unit transmits the message to the door control system. The disadvantage of the pressure wave system, however, is that it is subject to frequent breakdowns as a result of condensation formation, particularly in response to large temperature fluctuations. Furthermore, it only detects larger objects that are stuck between the doors.
Because of these difficulties, many public transport companies and door manufacturers have been searching for alternatives. Contributing also to this interest in an alternative system is the fact that a large portion of the accidents that occur result from objects of relatively small dimensions.
On the initiative of the Munich Municipal Transport Authority, the Hübner GmbH (a leading supplier of vehicle components for buses and rail vehicles) has dealt intensively with the subject of “passenger boarding monitoring”.
The resulting development is an exceedingly sensitive and easily installed “Gap Detection System” (GDS) that has now been in broad general use for approximately seven years.
The relevant provisions and directives for vehicle doors are specified in the European Standard EN 14752 and the German Standard VDV 111. These standards specify, for example, the prescribed dimensions of a test object (30 x 60 mm) and the closing forces for the door.
The Gap Detection System (GDS) reacts with great sensitivity and even recognizes smaller objects such as a baby carriage wheel, a child’s foot or a dog leash. The system functions on the basis of changes in resistance. Objects down to a thickness of 5 mm are reliably detected between closing exterior swinging doors. The resulting impulse signals the driver that door interference is occurring. The door opens and the vehicle brakes. Objects as small as this are not detected by pressure wave equipment.
Through the use of a particular “green light - driver notification” arrangement, it is possible to integrate a detection pause in the form of a time delta -- i.e., between the detection of a stuck object and the processing of the impulse (door opening). This is done through an electronic evaluation unit connected to the door control system.
This system has now become the standard solution in the business segment Door Monitoring Equipment for public transport vehicles. Most of the public transport operators and rail companies even include the Gap Detection System (GDS) in their technical specifications when acquiring new vehicles.
The GDS technology can usually also be integrated in retrofitting or vehicle life extension programs for existing vehicle fleets. Public transport operators can generally implement the system in the door control system on their own without expensive software updates.
Leading door system providers in public transport also use the Gap Detection System technology as the preferred standard in their new vehicles.
In addition to the Munich Municipal Transport Authority, the Berlin Transport Authority operating in Berlin has the longest experience using the system. The German Railway is currently modernizing the entrances of their passenger train fleet and equipping them with the Gap Detection System. It is also planned to equip the high-speed ICE train fleet with the system.
The responsible technical regulatory authority for the German rail system (EBA) located in Bonn explicitly calls for the use of the Gap Detection System (GDS) in two technical publications (March and September 2008) in the recommissioning of old vehicles or the acquisition of new vehicles.
Through practical experience and extensive testing over many years, it has been possible with the GDS to develop a system that provides optimal and affordable protection to passengers as they board and leave public transport vehicles.
Dipl.-Ing. Ralf Waibel
HÜBNER GmbH, Kassel
