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British Rail Mark 4
The British Rail Mark 4 is a class of passenger carriages built for use in InterCity 225 sets on the East Coast Main Line between King's Cross, Leeds and Edinburgh. Withdrawals began in 2019, with some being sold for further use with Transport for Wales between Cardiff and Holyhead.
A small build compared with the Mark 2 and Mark 3 designs, 314 Mark 4 coaches were built between 1989 and 1992 by Metro-Cammell's Washwood Heath factory to operate services on the newly electrified East Coast Main Line. They were operated by London North Eastern Railway and its predecessors in 30 fixed formations of nine carriages, with a Class 91 locomotive and Driving Van Trailer.
The Mark 4 is an all-steel coach incorporating a number of improvements over the Mark 3 stock - notably the inclusion of automatic push-button operated plug-type doors, in place of manually operated slam-doors, fully sealed gangways and controlled emission toilets (CET). Body shells were built by British Rail Engineering Limited (BREL) and Società Italiana Ernesto Breda.
After a period of evaluation in 1988, Swiss SIG type BT41A bogies were selected rather than BREL Type T4 bogies when BREL could not provide commercial guarantees on the demanding lateral ride comfort required for 140 mph (230 km/h) running (BT41B/C refer to the bogie types used on the Mk4 DVT).[full citation needed]
However, during the first year of operation in 1989, complaints were made about the "lively" ride of the coaches. This required modifications to the damper and spring rates of the bogies and the fitting of inter-coach car coupler dampers to improve damping between the vehicles. Disabled access was another priority of the design, so the door vestibules were enlarged to allow a larger turning circle for a wheelchair. With continually increasing levels of overcrowding, the 'gangway passenger' had become an important consideration, so the vestibule environment was improved with carpeted walls, better lighting, sealed gangways, and carriage doors plus four flip-down seats per vestibule (since removed and replaced with bench style perch seats).[citation needed]
Many of these innovations came from the abandoned Advanced Passenger Train, upon which the Mark 4 was heavily based. This influence was most obvious with the profiled sides, intended to allow the retrofitting of tilt-equipped bogies derived from the APT. This would have allowed up to 6° of tilt; modified coaches would have been designated Mark 4 T, but this plan was abandoned in January 1986. The business case for the Mark 4 also anticipated their operation on the West Coast Main Line as a follow-on order after the East Coast Main Line electrification, but after the failure of the InterCity 250 project to gain Treasury support, British Rail ordered a small number of Class 90 locomotives to supplement existing locomotives on the West Coast Main Line.
The Mark 4 has gained widespread praise for its exceptional crashworthiness, something that was proven in the Hatfield and Selby crashes, where experts identified the integral construction of the vehicles as being a key factor in restricting the death toll.
The Class 158 and Class 159 diesel multiple units, although superficially similar, are not based on the Mark 4 bodyshell; the Mark 4 is derived from the Class 156.
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British Rail Mark 4 AI simulator
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British Rail Mark 4
The British Rail Mark 4 is a class of passenger carriages built for use in InterCity 225 sets on the East Coast Main Line between King's Cross, Leeds and Edinburgh. Withdrawals began in 2019, with some being sold for further use with Transport for Wales between Cardiff and Holyhead.
A small build compared with the Mark 2 and Mark 3 designs, 314 Mark 4 coaches were built between 1989 and 1992 by Metro-Cammell's Washwood Heath factory to operate services on the newly electrified East Coast Main Line. They were operated by London North Eastern Railway and its predecessors in 30 fixed formations of nine carriages, with a Class 91 locomotive and Driving Van Trailer.
The Mark 4 is an all-steel coach incorporating a number of improvements over the Mark 3 stock - notably the inclusion of automatic push-button operated plug-type doors, in place of manually operated slam-doors, fully sealed gangways and controlled emission toilets (CET). Body shells were built by British Rail Engineering Limited (BREL) and Società Italiana Ernesto Breda.
After a period of evaluation in 1988, Swiss SIG type BT41A bogies were selected rather than BREL Type T4 bogies when BREL could not provide commercial guarantees on the demanding lateral ride comfort required for 140 mph (230 km/h) running (BT41B/C refer to the bogie types used on the Mk4 DVT).[full citation needed]
However, during the first year of operation in 1989, complaints were made about the "lively" ride of the coaches. This required modifications to the damper and spring rates of the bogies and the fitting of inter-coach car coupler dampers to improve damping between the vehicles. Disabled access was another priority of the design, so the door vestibules were enlarged to allow a larger turning circle for a wheelchair. With continually increasing levels of overcrowding, the 'gangway passenger' had become an important consideration, so the vestibule environment was improved with carpeted walls, better lighting, sealed gangways, and carriage doors plus four flip-down seats per vestibule (since removed and replaced with bench style perch seats).[citation needed]
Many of these innovations came from the abandoned Advanced Passenger Train, upon which the Mark 4 was heavily based. This influence was most obvious with the profiled sides, intended to allow the retrofitting of tilt-equipped bogies derived from the APT. This would have allowed up to 6° of tilt; modified coaches would have been designated Mark 4 T, but this plan was abandoned in January 1986. The business case for the Mark 4 also anticipated their operation on the West Coast Main Line as a follow-on order after the East Coast Main Line electrification, but after the failure of the InterCity 250 project to gain Treasury support, British Rail ordered a small number of Class 90 locomotives to supplement existing locomotives on the West Coast Main Line.
The Mark 4 has gained widespread praise for its exceptional crashworthiness, something that was proven in the Hatfield and Selby crashes, where experts identified the integral construction of the vehicles as being a key factor in restricting the death toll.
The Class 158 and Class 159 diesel multiple units, although superficially similar, are not based on the Mark 4 bodyshell; the Mark 4 is derived from the Class 156.