In the years after World War II, two massive changes were made to the railway system of the United Kingdom. In 1947 the entire network was nationalised, removing the Big Four private companies¹ that between them owned and controlled the lion's share of the network. The powerhouse of their systems had been the steam locomotive, an ageing technology. Almost immediately, the newly-nationalised British Railways was faced with competition from the road network. Road haulage was becoming increasingly popular and the private car more affordable for the average family. It was increasingly obvious that steam traction was outdated and something new was needed. In 1955, a programme of upgrades to the railway system was initiated – the Modernisation Plan.

The Post-War Scenario

At the time it was nationalised, the government's new public utility was in a sorry state, having suffered years of neglect. There had been no investment, and ongoing maintenance of the infrastructure and rolling stock was minimal. Nevertheless, steam locomotives had played a vital part in helping win the war, moving troops, supplies and munitions on top of their regular passengers and freight. Despite the extra traffic and longer trains, the railways did not receive as much money, as the government took a large part of the earnings. Steel and other materials were prioritised for war use, and the railway companies lost many men to war service; maintenance was not a priority. The RAF had defended the skies of the Kingdom, and hence the country's railway network, while inflicting crippling damage on the continental rail system. In Europe, the destruction caused to the railways necessitated an almost complete rebuild, whereas the relatively unscathed UK network continued the wartime policy of 'make do and mend'.

A Railway for the Future

In planning for a railway for the future, a key decision would be the choice of traction power. Would this be the end of the line for steam? There were three alternatives available – diesel power, electric power or build more steam locomotives – each having their own pros and cons.

Steam Power

Pros

• Steam was a tried and tested technology.
• Steam locomotives were cheap to build.
• Steam ran on coal which was cheap and readily available.
• Large steam locomotives were lighter than equivalent diesel locomotives of the same size because they carried their fuel in a tender. This meant that the weight was spread across a lot of axles, causing less stress on the rails.
• The railway had a huge existing infrastructure to deal with steam construction and maintenance, and had thousands of skilled mechanics and drivers
• Recent developments in steam power meant that it could approach the efficiency of internal combustion.

Cons

• Because their fuel and water were pulled behind them, tender engines could actually pull more when they were low on fuel. Tank engines on the other hand suffered because they lost traction as the weight available for traction was reduced.
• Even going forwards, steam locomotives have a limited visibility, the driver and fireman each looking out of small windows along the length of the engine. Each man could only see half of what was ahead, and that was when smoke wasn't obscuring their view.
• Steam power was noisy, smelly and dirty.
• To keep running a national system using pre-Victorian technology was embarrassing.
• Steam locomotives could not run 24-7, and they had to be kept with a lit fire even when they were not being used.
• Steam locomotives need a large maintenance crew and lots of checks and cleaning both before and after use.
• A locomotive's traction comes from the weight over the powered wheels. Tender steam locomotives kept their fuel and water in a tender, which didn't provide weight over the driving wheels. Most steam engines, especially those designed for faster services, had small support wheels to allow higher speeds or larger boilers and fireboxes. These also meant that less weight was available for traction.
• Steam locomotives generate most of their pulling power at very low revs, but with normally less than half their weight available for traction, they were very prone to slipping when starting.
• Driving and maintaining a steam locomotive was hard and dirty work. There were many more opportunities in the post-war world for people who wanted a job, so it was more difficult to attract drivers.
• It was dangerous to run most tender engines backwards at speed because of reduced visibility, so turntables and turning triangles were needed across the network.
• Steam locomotive performance depended greatly on the quality of the coal, which varied across the country.

Diesel Power

Pros

• Diesel power didn't need a huge investment in new infrastructure.
• Diesel locomotives could be turned on and off when needed.
• Diesel locomotives could run 24-7 if needed.
• Diesel locomotives could be driven either way around without visibility problems.
• Diesel power was much more useful than steam for low power units like railcars and multiple units
• A diesel locomotive carried its fuel onboard so had greater weight for traction. A diesel shunter could carry a few weeks of fuel onboard.
• Most diesel locomotives had all their wheels available for traction, which combined with the greater control that their transmissions offered, meant that they did not slip on starting and could accelerate a lot better.
• With better acceleration, and without the need to stop for water, coal or to change engines, journey times could be decreased.
• Diesel shunters had proved a success where they had been tried.
• Internal combustion was more efficient than regular steam.
• Diesel locomotives just needed to carry around their fuel, and not many tons of water as well.
• One diesel locomotive could replace a couple of steam locomotives since they could run all day.
• Diesel locomotives were easier to drive, and while they often had a second man in the cab, he did not have anywhere near as hard a task as a steam fireman. The cab of a diesel locomotive would have been a much more comfortable place to work, as befitted the second half of the 20th Century.
• Diesel locomotives needed less maintenance and didn't have the long checklists of oiling and cleaning before and after use.
• A new fleet of diesel locomotives could be an advert for Great British engineering.
• There was less chance of line side fires from sparks and hot ash thrown off by steam engines.

Cons

• Diesel power was still dirty, still noisy and still pretty smelly.
• Aside from shunters, some light railcars and a few experimental locomotives, it was still a largely untried technology.
• Diesel locomotives were much more complicated and more expensive than steam.
• One of the largest workforces in the country could need completely retraining to be able to build, maintain and run diesel locomotives.
• Diesel locomotives were heavier than steam locomotives of equivalent power and had their weight spread over less wheels, meaning that the track, trackbed and civil engineering would have to be strengthened for larger locomotives. Conversely, they didn't suffer from hammer-blow².
• Nobody had designed a diesel locomotive that was as powerful as the largest steam express locomotives.
• Oil had not yet been discovered in the North Sea, which would mean that it would have to be imported. Oil was paid for in dollars. Problems with the exchange rates and balances of trade put paid to a recent experiment to run steam engines on oil.
• Most passenger carriages were steam heated, so additional boilers would be needed in locomotives to be able to heat the coaches.
• Diesel freezes at -9°C, a temperature not unheard of in British winters.

Electric Power

Pros

• Electric power was clean as all the dirty power generation took place in power stations situated away from towns and stations. They were also quieter and less smelly.
• Electric locomotives were simpler than diesel and steam locomotives and had a lot less moving parts.
• Electric locomotives could be driven from either end.
• All the weight of the locomotives was over the driven wheels, and because of the way power could be applied gradually, they were not prone to slipping.
• Electric locomotives were lighter than diesels or steam of equivalent power, so track strengthening wasn't needed.
• Electric power could be useful with lighter workings, such as multiple units.
• Electric multiple units were a lot quieter than locomotive-hauled trains and diesel units so could be used in urban areas until much later in the evening.
• If tunnels are being built for electric traction there is no need to build in ways of removing exhaust gases.
• Electric trains had been successfully running suburban services for decades in the North West and South London, not to mention on the London Underground.

Cons

• The infrastructure for electric traction was extremely expensive. Not only did the new third rail or overhead cabling³ need to be put in place, but also methods of power generation.
• A number of different systems were already in use in different parts of the country, and most were incompatible with each other. Some used a third rail system, some a fourth rail system, others had overhead wires. Some used Alternating Current (AC), others used Direct Current (DC). There was also a range of voltages used.
• While a diesel or steam train could work anywhere (within weight restrictions), an electric train was confined to lines where it could get power. This would mean that rerouting a train due to an accident or engineering works would be difficult.
• The romantic image of a train in the middle of the landscape isn't as picturesque once overhead line equipment has been installed. Also high winds and falling trees can damage the lines.
• Third rail systems are prone to icing over in cold weather. Also they are a significant danger for people trespassing on the railway. Third rail isn't used in depots due to the danger of people stepping on the live rail.

The Standards

Managers and experts looked over all the options and came to a conclusion. The best way forward was by mass electrification. However, in post-war Britain, the railways were losing favour fast. It was forgotten that the railways had played a vital part in winning the war, and now they faced massive competition from the roads. The road haulage lobby had more swing with the government and more people than ever owned private vehicles. The railways could not afford to introduce electric traction across the system in one big sweep. It was estimated that it would take until the 1980s to electrify all the main lines.

As a temporary measure, they decided to build a new fleet of British Rail 'Standards' steam locomotives to supplement the existing fleet while lines were being electrified. These locomotives were to be cheap to build, and for steam locomotives, easy to maintain and to run. Construction of these started in 1951 and ended in 1960, when a total of 999 had been built.

Modernisation Plan

The 1955 Modernisation Plan⁴ put forward a new vision for the rail network. It decided in favour of electric and diesel power over steam locomotion, and encouraged the use of multiple units instead of small locomotive-hauled passenger trains. Being the 1950s, atomic power was considered but decided against it for onboard train power. It would be another 16 years before British Rail patented an atomic-powered vehicle, but this would be a space ship.

It was decided that on top of the existing suburban electric systems, the lines out of Liverpool Street to Essex and East Anglia would be electrified, as would the London, Tilbury and Southend Line from Fenchurch Street. The Southern region would have its electric network extended to cover most of the main lines to the Kent Coast. The Glasgow suburban network would get electric power. Both the West Coast and East Coast main lines would also be upgraded.

Diesel multiple units would be introduced to replace locomotive-hauled trains on city-to-city expresses, branch lines and cross-country services. Diesels would replace steam locomotives for all shunting and for mainline services on non-electrified routes.

Steam locomotives were to be phased out, however it would be another five years before the engine workshops stopped producing new steam locomotives. Despite the report recognising their 40-year working life, steam power was phased out after 14 years.

Two other major investments envisioned by the Modernisation Plan were refurbishing a number of stations and improving the efficiency of freight transport. Freight wagons would be required to have fitted brakes to allow safer and faster running. Giant marshalling yards would be built across the nation to allow freight trains to be broken apart and rearranged quickly.

In order to fund this project, the government loaned the railways a vast amount of money.

Bring on the Diesels

The government saw the introduction of a new fleet of diesel locomotives as a chance to show off the engineering prowess of British manufacturers. It asked for a range of locomotives grouped into 'types' of similar sizes and powers. Within these types different manufacturers produced examples using engines and components from leading British companies.

On top of various classes of shunters, the four locomotive types were:

• The Type 1 locomotives of 800 to 1,000hp
• The Type 2 locomotives of 1,001 to 1,499hp
• The Type 3 locomotives of 1,500 to 1,999hp
• The Type 4 locomotives of 2,000 to 2,999hp

Later, the Type 5 would be introduced for the more powerful locomotives. Although only one class of locomotives was introduced into this type at the start of dieselisation, this was what most post-dieselisation locomotives were classified as.

Classification

Wheels and More Wheels

One way of grouping locomotives is by their wheel layout. While steam locomotives have a great variety of arrangements, diesel and electric locomotives are much simpler. Normally, locomotives have their wheels on bogies at either end. The UIC classification system, which is the one that tends to be used, uses letters to describe the order and number of powered and unpowered axles. Powered axles are represented by letters, so A represents one powered axle, B represents two and so on. If each axle has its own traction motor, common with electric transmission, then it is shown with a small o afterwards, for example Co. Sometimes locomotives have unpowered axles to help spread their weight, these are represented by numbers.

For example, a Bo-Bo would be a locomotive that has two bogies, each with two sets of powered axles, each having their own traction motor. An A1A-A1A locomotive has two axles, each with three sets of wheels. The middle axle on each bogie is unpowered.

If the wheels are coupled together, as on shunters, then conventionally we use the steam notation, where we count the number of connected wheels, not the number of axles. A standard shunter is normally of the 0-6-0 arrangement, which means it has no unpowered wheels in front, six connected, powered wheels and no unpowered rear wheels.

Numbers and TOPS

It was normal convention to describe each class of locomotive by their manufacturer and what power group they belonged to. For example, one class was known as the English Electric Type 3. Locomotive numbers were assigned in batches to each class. They all began with the letter D but there was no convention on the numbers that followed. Unless you knew where each class's numbers stopped, it was hard to relate a number to a locomotive.

In the 1960s British Railways adopted TOPS - Total Operations Processing System - a computerised system to handle all their traffic. Each object, be it a locomotive or a multiple unit was given a number. The first two or three numbers denoted the class, the other three denoted their number within the class.

Diesel locomotives where assigned classes 01 to 69⁵. The assignment of numbers generally went in groups, so that shunters were Classes 01 to 14, Type 1 locomotives went up to Class 20, Type 2 locomotives went up to Class 31. The Class 37 was the last numbered type 3. Type 4 went up to the Class 53, although the Class 57 was later added into this type.

Electric locomotives were given classes 70 to 96. Diesel multiple units had classes 1xx and 2xx. Electric multiple units had 3xx, 4xx and 5xx.

Power to the Wheels

Having a huge, multi-litre engine is all well and good, but that power has to get down to the wheels. This is where the transmission comes in. Your average car has a gearbox full of cogs to supply the power from the crankshaft in the engine to the wheels. This is a mechanical transmission.

Diesel-Mechanical locomotives are generally low powered as the gearbox needs to be large, complex and very heavy duty to cope with the torque of a locomotive, and they have to be able to change gear while under load. Some multiple units were Diesel-Mechanicals. British Rail experimented with a high-powered express locomotive, but this didn't prove very successful.

Diesel-Hydraulic locomotives were very successful in continental Europe. They use a torque converter similar to an automatic gearbox in a car. In theory these are more efficient than other major forms of transmission, and lighter than Diesel-Electrics (an express Hydraulic was around 60 tons lighter than a similar Diesel-Electric). Because the axles are linked by driveshafts, it is impossible for individual wheels to slip on their own. This means they can put down a lot of pulling power. The Western Region of British Rail saw how well the German V2000 locomotives were performing in their native country, so decided to try them out there. However, they encountered a major reliability issue when worked on the British Network. In Germany, the locomotives were always worked well within their capabilities, but the management of the British network did not see the point of buying a 2,000 horsepower locomotive and not using all of its power. Many of the British Hydraulics suffered through being thrashed, and steam had to be brought in to replace them. The small, non-standard classes of Hydraulic locomotives were soon replaced by new Diesel-Electrics, although the technology is still in use in many multiple-units.

Diesel-Electric locomotives were essentially hybrids. Electric traction motors drove the wheels, getting their power from generators powered by a diesel engine. There was no mechanical link between the motor and the wheels, meaning that they were a simpler design. It also meant that they didn't suffer from transmissions breaking when they were unable to cope with the large forces generated. Diesel-Electrics was the technology of choice for most of the new locomotive fleet as it was able to cope with high power applications.

Electro-Diesel locomotives were a type of Electric locomotive, normally ones powered from the third rail. They also had a small diesel engine to help power them between gaps in the third rail and also in depots, where it was unsafe to have live third rail power.

A Sensible Solution?

Logically, the key to extracting the best of this new fleet of locomotives would be finding the best designs and then building large batches of the best design for each power class. This standardisation could allow the benefits of economy of scale such as lower build costs and cheaper spares, as well as drivers and other personnel being more familiar with the locomotives.

What would be stupid would be awarding contacts to many different manufacturers to make similar locomotives.

What would be monumentally stupid would be to award these contracts before the prototypes had been fully tested, just in case some of these brand new designs didn't actually work.

This last route was the one chosen by the rail industry under pressure from the government. Some classes of locomotive were soon found to be hopelessly unreliable, yet British Railways had to keep buying more. Many of the new diesels were out of use even before the end of steam.

The Failing of Modernisation and Dawn of Beeching

The government had lent the railways a huge amount of money, then told it how to spend it. Unsurprisingly, the railway was soon in even more trouble as it was struggling to make any profits. Action needed to be taken. A new chairman of the railways was appointed. He wasn't a railway man, he was an executive from ICI, and he commanded a huge salary. He was Doctor Beeching.

It is probably worth mentioning that the Transport Minister, Ernest Marples, who appointed Beeching had made his fortune out of road construction, and would not have objected to more roads being built. Of course, it would be out of the question to say that he would have profited directly from new roads, as he sold his shares in his construction company. To his wife. Marples ended up fleeing the country, wanted for tax fraud. In addition he was also wanted by both his former employees and tenants of the slums he owned.

Since the British rail network had been built by lots of competing companies, there was a massive amount of redundancy. Many towns and cities were served by multiple lines and stations. While Beeching is infamous for producing the report that suggested closing the underused lines, route closure happened before and after Beeching. Another consequence of Beeching and his reforms was that much of the minor freight traffic was taken onto the roads, meaning that the vast recently-built marshalling yards and many of the fleet of new locomotives, especially the smaller ones, were no longer needed.