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British Rail Class 91
The British Rail Class 91 Electra is a high-speed electric locomotive, which produces power of 4,830 kW (6,480 hp); it was ordered as a component of the East Coast Main Line modernisation and electrification programme of the late 1980s. The Class 91s were given the auxiliary name of InterCity 225 to indicate their envisaged top speed of 225 km/h (140 mph); they were also referred to as Electras by British Rail during their development and throughout the electrification of the East Coast Main Line.
The locomotive body shells are of all-steel construction. Unusually, the motors are body mounted and drive bogie-mounted gearboxes via cardan shafts; this reduces the unsprung mass and hence track wear at high speeds. The locomotive also features an underslung transformer, therefore the body is relatively empty compared to contemporary electric locomotives. Much of the engineering specification for the locomotive was derived from the research and operational experience of the APT-P.
The other end of the InterCity 225 train set is formed of a Mark 4 Driving Van Trailer, built with a similar body shell to the Class 91 locomotives but with only one driving cab.
The origins of the Class 91 are closely associated with the East Coast Main Line (ECML) on which it has been primarily operated. During the 1950s, British Rail had considered electrification of the ECML to be of equal importance to the West Coast Main Line (WCML), but various political factors led to the envisioned electrification programme being delayed for decades; as an alternative, high-speed diesel traction, the Deltic and then the InterCity 125, was introduced upon the route during the 1960s and 1970s. During the 1970s, a working group of British Rail and Department of Transport officials determined that, out of all options for further electrification, the ECML represented the best value by far. Its in-house forecasts determined that increases in revenue and considerable reductions in energy and maintenance costs would occur by electrifying the line.
Accordingly, between 1976 and 1991, the ECML was electrified with 25 kV AC overhead lines. The electrification was installed in two phases: The first phase between London (King's Cross) and Hitchin (including the Hertford Loop Line) was carried out between 1976 and 1978 as the Great Northern Suburban Electrification Project, using Mk. 3A equipment, covering 30 miles (48 km) in total. In 1984, the second phase commenced to electrify the northern section to Edinburgh and Leeds. During the late 1980s, the programme was claimed to be the longest construction site in the world, spanning more than 250 miles (400 km).
In 1989 the InterCity 225 was officially introduced to revenue service. That same year, the ECML had been energised through to York; two years later, electrification had reached Edinburgh, allowing electric services to begin on 8 July 1991, eight weeks later than scheduled. The ECML electrification programme was completed at a cost of £344.4 million (at 1983 prices), a minor overrun against its authorised expenditure of £331.9 million. 40 per cent of the total cost was on new traction and rolling stock and 60 per cent for the electrification of the line.
The electrification of the ECML necessitated the procurement of new high speed electric traction. The options and requirements for this trainset were hotly deliberated for a number of years. On 7 June 1978, the electric-powered prototype Advanced Passenger Train (APT) was unveiled; it was at one point intended for the APT to be the next major intercity express train. However, due to various factors including technical issues, the APT programme was curtailed during the summer of 1983. Shortly thereafter, two alternative options were explored, an electrified version of the InterCity 125 (known as the HST-E), and the Class 89 mixed-traffic locomotive; these were both intended to a peak service speed of 125 mph.
Some officials within British Rail pushed for more demanding requirements for the future Intercity trainset; reportedly, BR's Director of Mechanical and Electrical Engineering (M&EE) was a strong proponent for increasing the top speed to 140 mph. To facilitate this, tilting train technologies developed for the APT were explored. While BR's board had approved the ordering of a single Class 89 as a prototype, the Strategy Committee queried why the type had been favoured over a proposed 80-tonne Bo-Bo locomotive. While the Class 89 was thought to be a low-risk option for multi-purpose traction, it offered little advantage over the existing Class 87 in terms of speed. At the time, the 1950s era Class 81 and Class 85 electric locomotives were nearing the end of their viable service lives and were quite unreliable, but their withdrawal had effectively been ruled out by a national shortage of newer electric traction, in part caused by the APT's cancellation.
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British Rail Class 91
The British Rail Class 91 Electra is a high-speed electric locomotive, which produces power of 4,830 kW (6,480 hp); it was ordered as a component of the East Coast Main Line modernisation and electrification programme of the late 1980s. The Class 91s were given the auxiliary name of InterCity 225 to indicate their envisaged top speed of 225 km/h (140 mph); they were also referred to as Electras by British Rail during their development and throughout the electrification of the East Coast Main Line.
The locomotive body shells are of all-steel construction. Unusually, the motors are body mounted and drive bogie-mounted gearboxes via cardan shafts; this reduces the unsprung mass and hence track wear at high speeds. The locomotive also features an underslung transformer, therefore the body is relatively empty compared to contemporary electric locomotives. Much of the engineering specification for the locomotive was derived from the research and operational experience of the APT-P.
The other end of the InterCity 225 train set is formed of a Mark 4 Driving Van Trailer, built with a similar body shell to the Class 91 locomotives but with only one driving cab.
The origins of the Class 91 are closely associated with the East Coast Main Line (ECML) on which it has been primarily operated. During the 1950s, British Rail had considered electrification of the ECML to be of equal importance to the West Coast Main Line (WCML), but various political factors led to the envisioned electrification programme being delayed for decades; as an alternative, high-speed diesel traction, the Deltic and then the InterCity 125, was introduced upon the route during the 1960s and 1970s. During the 1970s, a working group of British Rail and Department of Transport officials determined that, out of all options for further electrification, the ECML represented the best value by far. Its in-house forecasts determined that increases in revenue and considerable reductions in energy and maintenance costs would occur by electrifying the line.
Accordingly, between 1976 and 1991, the ECML was electrified with 25 kV AC overhead lines. The electrification was installed in two phases: The first phase between London (King's Cross) and Hitchin (including the Hertford Loop Line) was carried out between 1976 and 1978 as the Great Northern Suburban Electrification Project, using Mk. 3A equipment, covering 30 miles (48 km) in total. In 1984, the second phase commenced to electrify the northern section to Edinburgh and Leeds. During the late 1980s, the programme was claimed to be the longest construction site in the world, spanning more than 250 miles (400 km).
In 1989 the InterCity 225 was officially introduced to revenue service. That same year, the ECML had been energised through to York; two years later, electrification had reached Edinburgh, allowing electric services to begin on 8 July 1991, eight weeks later than scheduled. The ECML electrification programme was completed at a cost of £344.4 million (at 1983 prices), a minor overrun against its authorised expenditure of £331.9 million. 40 per cent of the total cost was on new traction and rolling stock and 60 per cent for the electrification of the line.
The electrification of the ECML necessitated the procurement of new high speed electric traction. The options and requirements for this trainset were hotly deliberated for a number of years. On 7 June 1978, the electric-powered prototype Advanced Passenger Train (APT) was unveiled; it was at one point intended for the APT to be the next major intercity express train. However, due to various factors including technical issues, the APT programme was curtailed during the summer of 1983. Shortly thereafter, two alternative options were explored, an electrified version of the InterCity 125 (known as the HST-E), and the Class 89 mixed-traffic locomotive; these were both intended to a peak service speed of 125 mph.
Some officials within British Rail pushed for more demanding requirements for the future Intercity trainset; reportedly, BR's Director of Mechanical and Electrical Engineering (M&EE) was a strong proponent for increasing the top speed to 140 mph. To facilitate this, tilting train technologies developed for the APT were explored. While BR's board had approved the ordering of a single Class 89 as a prototype, the Strategy Committee queried why the type had been favoured over a proposed 80-tonne Bo-Bo locomotive. While the Class 89 was thought to be a low-risk option for multi-purpose traction, it offered little advantage over the existing Class 87 in terms of speed. At the time, the 1950s era Class 81 and Class 85 electric locomotives were nearing the end of their viable service lives and were quite unreliable, but their withdrawal had effectively been ruled out by a national shortage of newer electric traction, in part caused by the APT's cancellation.