Selective Door Operation
Encyclopedia
Selective Door Operation, also called Selective Door Opening (or SDO) is a mechanism employed primarily on train
s (although bus
es with multiple doors also generally have this feature) that allows the Driver or Conductor/Guard to open the doors of a train separately.
; 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
.
This is should not be confused with a Local Door Operation
(LDO) used on multiple units for the use of train crew and other staff. This could be argued as the same system, but in terms of the railway Rule Book is treated separately. This is used for passengers, at Conwy in North Wales, for example, but not as the norm.
To simplify, some trains that call at certain railway stations are too long for the platform. This caused an operational headache on old stock but was solved by Selective Door Operation. The Guard or Driver can choose which doors are to be opened so as not to allow passengers to disembark from carriages not standing at the platform.
In the UK various trains, either multiple units or coaches, have variations of the Selective Door Operating system. This usually depends on what the specific Train Operating Company and/or Train Leasing Company required, either at time of purchase or a later modification to an existing train to keep up to date with regulations.
Examples of these variations are as follows:
Many modern Selective Door Opening (SDO) systems are operated / controlled by Global positioning satellites (GPS), which locate the train at the specific station. As the train pulls into to the station the GPS identifies the trains positioning and tells the SDO control (which is located on the train) what station it is currently at. This then enables the correct side of the train and enables the correct amount of coaches doors to be opened, thus aligning the length of the platform.
Train
A train is a connected series of vehicles for rail transport that move along a track to transport cargo or passengers from one place to another place. The track usually consists of two rails, but might also be a monorail or maglev guideway.Propulsion for the train is provided by a separate...
s (although bus
Bus
A bus is a road vehicle designed to carry passengers. Buses can have a capacity as high as 300 passengers. The most common type of bus is the single-decker bus, with larger loads carried by double-decker buses and articulated buses, and smaller loads carried by midibuses and minibuses; coaches are...
es with multiple doors also generally have this feature) that allows the Driver or Conductor/Guard to open the doors of a train separately.
Purpose and operation of SDO
Selective Door Operation (SDO) is a system used by trains for the safe operation of the passenger doors at short station platforms. The term Selective Door Operation is used mainly in the United KingdomUnited Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
; 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
London Underground
The London Underground is a rapid transit system serving a large part of Greater London and some parts of Buckinghamshire, Hertfordshire and Essex in England...
.
This is should not be confused with a Local Door Operation
Local door operation
Local door operation refers to a procedure and system in place on railway rolling stock on the United Kingdom railway network. It is where a single door on a train is operated by its train crew from a crew operated switch, often on a train door control panel operated by the train's guard...
(LDO) used on multiple units for the use of train crew and other staff. This could be argued as the same system, but in terms of the railway Rule Book is treated separately. This is used for passengers, at Conwy in North Wales, for example, but not as the norm.
To simplify, some trains that call at certain railway stations are too long for the platform. This caused an operational headache on old stock but was solved by Selective Door Operation. The Guard or Driver can choose which doors are to be opened so as not to allow passengers to disembark from carriages not standing at the platform.
In the UK various trains, either multiple units or coaches, have variations of the Selective Door Operating system. This usually depends on what the specific Train Operating Company and/or Train Leasing Company required, either at time of purchase or a later modification to an existing train to keep up to date with regulations.
Examples of these variations are as follows:
- Most Class 170 Turbostar units, with certain exceptions like the 170 Mark 1, are fitted with SDO. This when operated de-selected all carriages behind the location in the carriage 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 MainlineMidland MainlineMidland Mainline was a British train operating company owned by the National Express Group and based in Derby. It was created after the privatisation of British Rail. Midland Mainline services operated from April 1996 to November 2007....
Class 170 mark 1 Turbostar Units were fitted with SDO. This was unusual in the fact it required the Driver to run the leading coach off the platform. The Driver then operated the SDO system before releasing the train doors. The result was the leading carriage only was de-selected. The Guard then closed the doors from an appropriate location. These units are currently in use with Cross Country Trains, without any need for this form of SDO.
- 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 as 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.
- First Great WesternFirst Great WesternFirst Great Western is the operating name of First Greater Western Ltd, a British train operating company owned by FirstGroup that serves Greater London, the South East, South West and West Midlands regions of England, and South Wales....
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 panel throughout the train. The Guard can then either de-select doors in front of that location or behind.
- Most Electrostars (Bombardier built) Class 375, 377, 378 and 379 all have SDO systems fitted and operate in the South eastern regions of the country. All these vehicles SDO’s are controlled / operated by GPS systems. The Class 377 being used on Southern and Thameslink Networks have an additional Hima-Sella Ltd Tracklink II system to augment the GPS system. The Tracklink II system consists of a balise fitted at short platform stations which sends specific data to the passing Class 377 exactly which station it is approaching and the length of the platform that it is entering. The Tracklink II system is required due to GPS not being accurate enough to determine exactly which platform the train is entering at multi-platform stations.
Many modern Selective Door Opening (SDO) systems are operated / controlled by Global positioning satellites (GPS), which locate the train at the specific station. As the train pulls into to the station the GPS identifies the trains positioning and tells the SDO control (which is located on the train) what station it is currently at. This then enables the correct side of the train and enables the correct amount of coaches doors to be opened, thus aligning the length of the platform.