Signal Systems again?

You can't generalise like that, there are other factors to consider. Things may have changed now but line maintenance was not necessarily done by the line's own maintenance staff! For instance as a Piccadilly Line signal lineman working out of Acton Town depot my maintenance area included Wembley Park to Finchley Road on the Met and Hanger Lane to Ealing Broadway on the District as well as Charing Cross to Stanmore on the Jubilee and of course Cockfosters to Heathrow and Acton up to but not including Rayners Lane.

At the time there was no Jubilee line maintenance organisation as such it was shared between Picc line maintenance and Northern Line maintenance (responsible for JLE).

These days I believe that Tube Lines just does Jub/Northern/Picc maintenance with Metronet looking after the rest but I don't know whether localised depots are the order of the day or whether the maintenance is pooled. It was certainly a fact that when the Picc took over Wembley Park and Finchley Road depots from the Met the maintenance had previously been very basic and we spent a great deal of time bringing the area up to standard, both Met and Jub.

Although there are standards for everything, manning levels, depot locations, work ethics, budgetary constraints etc etc will all have an effect such that consistency of maintenance will vary from area to area.

Luck does play a part but in my book bad maintenance leads to bad luck! On the other hand there is always the possibility of an Act of God although generally speaking the causes are often human rather than divine, one of the great failings of outsourcing railway engineering maintenance and installation work to such a wide variety of subcontractors is a lack of awareness of potential signalling failure issues. I recall attending many failures caused by other contractors working on or about the track.

Sometimes problems would be lived with until they became urgent and that was a recipe for higher failure levels. At the end of the day it all boils down to matching resources to maintenance need and that can sometimes cost more than available resources allow. Managers fight a never ending chess game to keep on top of it all and I expect in the current economic climate the battle will become even harder to fight.