British Rail Mark 5

The British Rail Mark 5 was the designation given to the planned passenger rolling stock for the InterCity 250 project.

Background

The Mark 5 project was intended to produce a new generation of InterCity passenger rolling stock, anticipated for initial use on the West Coast Main Line, these would have been developed from the Mark 4 stock in service on the East Coast Main Line. The profile of the Mark 5 coaches was designed for non-tilting operation unlike the briefly contemplated use of tilting "Mark 4 T" stock on the West Coast Main Line which is evident in the sloping sides of the Mark 4 coaches. Following introduction on the WCML, it was suggested that the coaches could have been used as part of later IC250 builds for the East Coast and Great Western Main Lines, replacing the Mark 3 and Mark 4 coaches used in the InterCity 125 and 225.^[1]

Project Description

The initial intention of InterCity 250 was to build 30 full trains, each consisting of a Class 93 locomotive, nine 26 m long Mark 5 passenger coaches and a Mark 5 Driving Van Trailer. The coaches would be capable of 155 mph (250 km/h) and were specified to be equivalent in weight to the shorter Mark 4 coaches, which were felt to be overweight. The decision to increase the length of the coaches to 26 m from the 23 m of the Mark 4 was dictated by reduced maintenance costs following British Rail studies which indicated that such a length was feasible within the UK loading gauge. Indeed during 1987 British Rail had considered increasing the length of the Mark 4 to 25.5 m (with 18.13m bogie centres^[2]) but the in-service date of 1989 and complexity of changing the design to suit caused the variation order to be shelved.^[3]

The Mark 5 coaches would have been streamlined with powered plug fit doors and potentially fitted with an active suspension system which would help to contribute towards a desired 30% improvement in ride quality compared to the Mark 3 coach - then the benchmark used by InterCity.^[4] Development of the Mark 5 rolling stock was accompanied by research into improvements in track quality needed to achieve the desired ride quality at 155 mph. Some of this work was undertaken via computer simulations using the vehicle dynamics software "VAMPIRE" for operation on both the WCML and ECML; this utilised track geometry and ride quality data gathered from Mark 4 rolling stock test runs on the ECML.^[5]

The interior of mockups (designed by FM Design,^[6] and constructed within marine plywood enclosures at British Rail's Engineering Development Unit, in the Railway Technical Centre, Derby, England during 1991) indicated a 2+2 seating arrangement in standard class (88 seats per coach) with 2+1 in first class (52 seats per coach^[7]). The Driving Van Trailer (DVT) would also have come under the Mark 5 project remit. These would have resembled the Class 93 locomotives, with luggage space, a kitchen and a driving cab, similar to those commissioned for the InterCity 225 project.

Creating the Class 93's alone would have cost £380 million. With limited funding after the East Coast Main Line project was completed, the costs were deemed too high, and the project was terminated.

Legacy

After the InterCity 250 project was scrapped, Virgin Trains, who have operated the West Coast Main Line franchise since the privatisation of British Rail, commissioned new rolling stock in the form of Class 390 electric multiple units—rather than the Class 93 locomotive and separate Mark 5 carriages proposed by British Rail. Current Network Rail track design standards use the Mark 5 coach to represent coaching stock with 19m bogie centres.^[8]

References

1. ↑ "Modern Railway Transportation", J Ellis and C Green, Institution of Civil Engineers, 1993.
2. ↑ "Dynamic Predictions For 25.5m MKIV Coach With SIG Bogies", Report No. LR-VDY-011, BR Research Division, 01 April 1987.
3. ↑ "The Mk 4 and Mk 5 coaches for British Rail Intercity Part 2 : testing, commissioning and service experience with the Mk 4 coach and development of the Mk 5 specification", J A Higton and D R Temple, Proceedings of the Institute of Mechanical Engineers, Vol 206, 1992.
4. ↑ "ATA Evaluation - Part 1", Report No. LR-VDY-123, BR Research Division, 28 November 1989
5. ↑ "Mark IV Coach Ride Calculations For Comparison With Mark V Coach Specifications", Report No. LR-VDY-91, BR Research Division, June 1991
6. ↑ Designers Journal, Number 67, May 1991.
7. ↑ "New Age Of Train", Scottish Herald, 13 March 1991.
8. ↑ Network Rail Track Design Handbook NR/L2/TRK/2049 Issue 12

See also

• British Rail Class 93
• InterCity 250