Signal Failures

A signal failure is a generic term used to cover a wide range of things and is used when something related to the signalling system causes delays. That something could be a track circuit failure, a train stop failure, a points machine failure, an axle counter failure, a cable fault or a hundred and one other things. There is no one single cause, just an effect - ie the service gets delayed.

As there is no one single cause there is no utopian solution. Replacement systems such as that on the Jubilee don't use trainstops with their pneumatic and mechanical components so failures from that are eliminated but the new systems have their own issues such as susceptability to damage of the track mounted cable where this is used, greater reliance on software and computer systems etc.

Clearly the hope is that the new systems are more reliable than the old. Someone will no doubt know how the lines with conventional signalling compare in terms of reliability with those that have the new systems.

Generally speaking one gets what one pays for, that is to say that although well made conventional signalling equipment was expensive to purchase and maintain it had dependable longevity. I am not so sure that modern signalling equipment will stand the test of time so well, in recent years the drive to economise upon the costs of maintaining traditional signalling equipment led to replacement of expensive parts with cheaper ones, a false economy borne out by subsequent failures. Short termism is a very British disease that had not affected the Underground until relatively recently and I would question why there is a need to use new technology, after all LUL still has a great deal of 100+ year old technology in service which has stood the test of time and of course there is also plenty of 50+ year old technology in service as well.

Modern technology is not necessarily better, there are no guarantees in that regard although I believe that LUL generally specifies a minimum expected working life of 20 years. One has to wonder if 'S' stock will last that long given the scrapping of 1983 stock and the problems associated with 1992 stock.

In the long run new technology will prove to have been more expensive to design, install and maintain as it will be life expired far more quickly than that employed in the past.

Oh really? Look back in history and you'll better appreciate just what an intensive service is, there hasn't been such on the LT/LU system in decades!

As for any and all other things signalling and rolling stock I would say that it boils down to a chicken and egg situation complicated by the differing aspirations of individual line organisations and with a corporate management that appears to have no clear image of the future to work towards.

Never forget that LT had ATO almost 50 years ago, rolling stock and signalling that worked together and worked well, what's so different now? AFAIK the problem is that politicians and accountants control the purse strings but have little or no concept of engineering design and the financial rewards associated with longevity, standardisation and excellent installation and maintenance practices.