The Inter-City 125 (Class 43)

Max Commercial Speed	125 mph (200 km/h)
Speed Record	148 mph (237 km/h)

Introduction

In the late 1970s there was a whole new game on the railway scene, the high speed era was dawning. Lessons were being learnt that a fast and frequent service would attract a large amount of paying customers, as seen in Japan. Britain was unconventional in its approach, most other countries electrified all the lines where fast trains might be needed. However electrification was deemed too expensive, so a diesel high speed train was sought after. At the time the fastest Diesel around was the Class 55 Deltic (now withdrawn) capable of an absolute maximum of 105mph. (170km/h), although usually Diesel trains never got over 100mph. Studies were done, and 125 mph or 200km/h came up as a reasonable speed that railways in the UK could cope with. Also, if tracks were upgraded properly, it could give rise to average speeds of express services of over 100mph, much high than the generally accepted average speed of 60mph at the time.

Success of the Inter City 125

The Inter-City 125 has very much been a great success, greatly reducing journey times all over the UK. It could often significantly reduce journey times not only because of its high speed but also because of the much more superior acceleration/deceleration than other diesels. The new trains caused an absolute surge in demand for rail travel and to begin with British Rail found it very hard to cope with the huge numbers. Today 197 power cars are in operation, so the train is a very common sight along mainlines in the UK. After development, Australian rail became interested in the engines, and the class 43 power cars were to form the basis for Australia's high speed train, the XPT. However the XPT is not as fast as its British counterpart.

Formation

An Inter City 125 is made up of two class 43 power cars, one at each end, and 8 or 7 trailers in the middle for passengers. Being diesel engines they are not that powerful, only generating 2250 hp in each engine, this is why two of them are needed for high speeds. Electric engines relatively speaking are much more powerful, the class 91 can generate over 6,000 hp. Another advantage is that having an engine at both ends, the train can travel in the opposite direction without and problems. The Class 43 uses the Paxman valenta diesel engine with a screaming Napier turbocharger

Diesels are very much slower than electric trains, for technical reasons. Diesels are heavier than electric trains, and also their engines have to spin at very high rpms to achieve high speeds. There are a lot more moving parts in a diesel engine than there are in an electric engine, so clearly friction would be higher. The big turbines on this diesel which suck in air to be compressed for burning, make this a very noisy engine, producing a very loud, high pitched scream when in use. Although some may not like it, I do because it adds a feeling of energy which adds to the excitement of travelling.

The Future of the Inter City 125

Many of the trains are now starting to reach 20 years old, but there is no reason why they shouldn't continue to run for at least another 10 years before it is likely they start to be withdrawn. Railway companies like the Inter City 125 because it is fast and extremely reliable, and a proven technology. However two major companies operating over non electrified stretches of line have ordered 125mph diesel multiple units, although these will be added to improve service to cope with increasing demand rather than to replace the Inter City 125. However the arrival of fast DMUs will start to cut away at the impression of the Inter City 125 as the UKs only diesel high speed train.

The Speed Record

When first introduced test runs where made which set a world record for a diesel train, 143 mph (230 km/h) and this record was broken in 1987 when the train set a record of 148 mph, which makes this the fastest diesel train in the world. The reason for this, is that all other countries to develop high speed train technology have only considered electric solutions, so high speed diesel technology has only really been developed here in the UK.

A new speed Record?

With privatisation Richard Branson has realised the importance of speed records as a form of publicity, and it is rumoured that he is doing up some of his class 43s to make some new record run attempts. However a lot of these engines are approaching 20 years of age so it may be difficult. Having said that they have been kept in good condition and are very reliable.

Who controls the trainsets after privatisation?

Midland Mainline (MML): 31 power cars

Great North Eastern Railways (GNER): 22 power cars

Great Western Railways: (GWR): 82 power cars

Virgin Railways: Virgin Cross Country (VXC): 54 power cars, Virgin West Coast (VWC): 7 power cars.

New Liveries

All of these companies are keen to stamp themselves on the engines, and the breed in the old Inter City Swallow livery is dying out. Here is a summery of what the new liveries look like. Click on the thumbnails for full size images.


Virgin Livery		MML Livery		GW Livery		GNER Livery