Complexity of change

In the very early days of the railway, Isambard Kingdom Brunel was summoned to the Houses of Parliament to be questioned about various aspects.

Monday, 28th January 2019, 3:27 pm

In answer to the question about the efficiency of the brakes on his trains, he replied cheerfully.

“Tolerably useless. Tolerably useless.”

In fact, the train drivers were expected to be so familiar with the characteristics of their trains that they knew exactly when to shut off steam so that the train stopped nicely at the platform, just where it was supposed to do.

The only brake available to the drivers at that time was a handbrake on the locomotive tender.

Some 150 years later, a young driver was taught to stop the local trains at the stations along the Thames Valley.

His instruction was as follows.

“Hit the platform at 50mph and make a full brake application.

“Halfway along, knock it off and you will stop just right.”

He found that the advice worked perfectly.

As train speeds have increased over the years, the criterion has been that high speed trains, running at 125mph, must be able to stop in the same distance as older trains, running at just 90mph.

At higher speeds it is no longer sufficient for the driver to see the line-side signals, they must also have the signals displayed in the cab.

The complexity of making these changes is enormous.

And, of course, with complexity comes cost.

At present, such speeds are achievable only on very limited stretches of existing lines, such as those north of York.

However, appropriate signalling is now being built into new high speed lines.

Older signals are gradually being replaced with newer ones.

In the accompanying image, this line in Norfolk still had its semaphore signals.

The northern part of the East Coast Main Line was re-signalled in preparation for the electrification of trains in the late 1980s.

Unfortunately, however, some of the new trains produced for this line cannot be used until they and/or the signalling have been modified.

This means that they are likely to be sitting in sidings for a large part of 2019.

The fact is that in many walks of life people appear to concentrate on a job without considering how it will affect or be affected by what else is going on around it.

And it turns out to be often much more expensive to have to modify something after it is made than it would have been to do it in the right way in the first place.

In transport, for example, one Government department has imposed an end date of 2040 on the production of new diesel road vehicles.

But this comes at the same time as another Government department has put a stop to the electrification of some lines and said that diesel trains must continue to be used.

The effect of railway planning takes much longer than 20 years to work through.

The trouble at present, of course, is that everybody in the Government seems to be too distracted by other issues to think much about practical matters.