25 Jan 2013

How much innovation?

How fast should railways innovate? The Advanced Passenger Train came about when British Rail imported a team of engineers from the aerospace industry. As an experimental project it was a success. But the aim was to introduce these trains into fleet operation. Fortunately a group of old school BR engineers had their own ideas of pushing mature technology just a little and were not prevented from pursuing them. The result was the HST and still no-one has actually got an effective replacement into service. And the HST itself had its share of teething troubles which went on for years.

But if we relied on only ever building what was safe from any risk then we'd be running a railway which didn't look much different from that in the 60's. Or would we?

Steady evolution or evolution by leaps and bounds?
The first 80 years of railways were dominated by steam power, which continued to play an important role until the 1950s. There was a steady development and a steady increase in power and performance, but attempts to move even marginally away from the mature technology of the time were a failure. Most improvements arose as a response to the deficiencies of the mature technology, resulting in steady evolutionary development.

Then came the introduction of electric traction from around 1900 onwards and that involved the application of robust mature technology and steady evolutionary progress, with DC or low frequency AC motors. These were  acceptable for short distance routes, but the shortcomings of power cars - poor ride quality - were an issue that was not resolved until the 1970s.

Electrification was given a boost by the development of improved systems of rectification including solid state devices, which made possible the introduction of 25kV /50 hz systems with reduced costs, and that paved the way for a second wave of electrification of main lines. Again the process was evolutionary and fairly trouble free. In more recent times we have seen the introduction of variable frequency 3-phase motors which have made innovations like distributed drive more feasible. There was nothing new about the concept but it took the development of power electronics to make them practicable. Again, this has been an evolutionary development with lots and lots of testing being done.

Internal combustion was another matter. Locomotives with marine diesels were built quite early in the twentieth century but high powered diesels designed for constant output direct to a propeller and are inherently ill-suited to railway conditions. Direct drive is impossible and expensive electrical transmission systems are needed. As a result, the cost per horse power was five times that of a steam locomotive and for this reason they made little progress until the 1950s.

On the other hand, low powered underfloor engined internal combustion engines with mechanical transmission transferred quite well to the railway environment and were the basis of the fairly successful DMU programme initiated in the mid-1950s. I say fairly successful, because the new diesel trains provided an inferior passenger environment to the steam hauled trains they replaced, and this is a problem that has been compounded in recent years with the development of high speed inter-city DMUs, where the concept is even less suitable when the engines are large powerful units.

Apart from the DMU programme, the transition from steam to diesel in Britain was wasteful and troublesome. Few of the locomotive classes seem to have been really satisfactory and many were short-lived or needed expensive fleet modifications. The country is still living with the consequences today.

In the same period, the cost of rolling stock has increased from around £6000 per hauled vehicle in 1955 to £1 million today (some would say even more). Allow a generous factor of 40 for inflation and that is a real cost increase by a factor of 4. Now whatever else you might say about the latest trains, they are not four times as fast or four times as comfortable or four times anything else that is perceptible to the passenger. Nor are they four times easier to maintain. The might be four times safer but that is not a matter of cost but a result of putting the metal in the right place due to the use of FE analysis, and that was largely sorted out when the mark 3 bodyshell structure was developed. So it looks as if things have gone well past the point of diminishing returns.

An alternative history
What would the railway look like if things had gone the way I would have liked to have seen it go? In the first place, there was no intention in 1955 of getting rid of steam within a decade, as actually happened, very wastefully Thus electrification would have proceeded much faster, with both the ECML and WCML and the Midland being wired by the late 1970s, and the core GW routes following by the mid-1980s, after which the wires would have been extended to places like Aberdeen, Inverness and Plymouth by 2000, as well as linking routes such as Southampton-Bristol. Many of the Beeching closures would not have happened, including such routes as the Great Central and lines in southern England where there were already signs of development pressure.

Speeds would have crept up, mostly through incremental improvements to the infrastructure, however, probably not much above 110 mph. The aim would have been to provide a cost-effective service with affordable walk-on fares available outside the high peak times.

Such a railway is far from the one Britain actually ended up with.

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