Selective door operation
The examples and perspective in this article may not represent a worldwide view of the subject. (December 2009) |
Selective door operation (SDO), also known as selective door opening, is a mechanism employed primarily on trains (although buses with multiple doors also generally have this feature) that allows the driver or conductor/guard to open the doors of a train separately.
Selective Door Operation enables trains to call at a station where the platform is shorter than the train. Some doors can be prevented from opening to ensure that passengers do not disembark from any carriages not standing at the platform. The term Selective Door Operation is used mainly in the United Kingdom; some train operating companies used the term ‘Door De-Select’. A version of this is used in other countries and on other rail systems such as the London Underground.
UK variations
In the UK various trains, either
- Most Class 170 Turbostar units, with certain exceptions like the 170 Mark 1, are fitted with SDO. This when operated de-selects all carriages behind the carriage in which the train doors are being operated, so the guard can operate the SDO, allowing any length of train to occupy the platform as long as it can take one carriage.
- Former Midland Mainline Class 170 'Mark 1' Turbostar units are fitted with SDO. This form of SDO was operated by the driver, who would run the leading carriage off the platform and deactivate the doors in the leading cab before releasing. These units are currently in use with CrossCountry, without any need for this form of SDO.
- Driver Onlyis now in operation on the entire London Overground network.
- Class 350, 444 and 450 Desiro electric multiple units use a system call Unit De-Select. This allows the guard of the train to de-select an entire unit on a train while they are in working in multiple from one of the driving cabs, meaning that an 8 coach 350 or 450 set for example, made up of two units (each unit has 4 coaches), can have one set de-selected. The Class 444 is made up of 5 coaches per unit but the principle is the same.
- Great Western Railway High Speed Train sets have SDO at almost all door locations. These trains are of the slam-door variety and fitted with the central door locking system. The guard operates the SDO system from most door control panels throughout the train. The guard can then either de-select doors in front of that location or behind.
- Class 180 units are fitted with SDO, this is operated by the driver (who also releases the doors) from a switch in the leading cab.
- Most Electrostars (Bombardier built) Class 375, 377, 378, 379 and 387 have SDO systems fitted and operate in the southeastern region of the country. A Global Positioning System (GPS) receiver located on the train passes location data to the MITRAC Train Control Management System,[2] which uses its database of platform lengths to determine how many doors will be released when the driver presses the 'door open' buttons at a station. The Class 387s in use on the Govia Thameslink routes have an additional Tracklink II[3] system to augment the GPS. The Tracklink II system consists of a balise fitted at short platform stations which sends data to the approaching train showing which station it is approaching, and the length of the platform that it is entering. The Tracklink II system is necessary because GPS is not accurate enough to differentiate between platforms at a multi-platform station.
- All Class 195 and Class 331 CAF Civity trains have ASDO systems fitted, the vast majority of services will operate as 3 and 4-car formations (doubled 2-car for the Class 195), some 3-car units will be doubled for 6-car services. ASDO is fitted on routes where platform lengths cannot fully accommodate the train. The ASDO system is linked to an automated system which informs passengers through announcements and the passenger information screens located in each saloon.
- On .
International variations
Selective door operation is implemented at certain railway stations in the United States. In the
On the Staten Island Railway, the Richmond Valley station only allows for the first three cars to open, due to the short platforms which cannot fit four 75-foot-long (23 m) cars. In addition, the last car for St. George-bound trains do not open at Clifton, due to the wide space from trains caused by the platform's curvature. Before they were demolished in 2017, the Atlantic and Nassau stations only allowed the last car of a train to open its doors at the platforms.
In
In
In many NSW TrainLink stations in New South Wales, Australia, due to shorter platform length than trains, only selected doors will open. One example would be Wondabyne railway station or Zig Zag railway station, where the extremely short length of platform only allows rear door (next to crew cab) on the last carriage to be opened.
In New Zealand, “selective door opening” is used on the Wairarapa Connection commuter train, as the Maymorn railway station platform is not long enough to accommodate all the carriages, and Maymorn passengers are restricted to the first three carriages.
Limitations
Most modern Selective Door Opening (SDO) systems receive their positioning data from the
- The train stops beyond the appropriate stop mark and the driver releases the doors
- The train stops before the appropriate stop mark and the driver releases the doors
- The driver releases the doors on the wrong side of the train
Local door operation
Selective Door Operation is different from Local Door Operation (LDO), which is used on many trains by train crew and other staff.
References
- ^ "Archived copy" (PDF). Archived from the original (PDF) on 11 July 2015. Retrieved 10 July 2015.
{{cite web}}
: CS1 maint: archived copy as title (link) - ^ The Class 377 Electrostar: Selective Door Operation / SDO Risks. First Capital Connect. 2009. p. 134.
- ^ "Sella Controls: Tracklink solutions". www.sellacontrols.com. Retrieved 3 July 2017.
- ^ "Functioning and Control of Exterior Doors on Passenger Vehicles" (PDF). Rail Safety and Standards Board. Retrieved 18 June 2018.