Protecting the Infrastructure 02/07

[PHILIPE]

A new one here. All starting/terminating Warminster services are cancelled between Warminster due, following a points failure, Network Rail are "protecting the infrastructure" due to the warm weather

 

[Stew998]

Are they saying the weather is affecting points and it could be damaging to run trains over them? Sounds like it could be similar to the buckled rails issue.

On the London to Brighton line there are significant delays this evening due to "multiple signal failures" between Haywards Heath and Brighton, points failure at Redhill and a broken down train in South London.... are the infrastructure problems heat related I wonder? (Not that they're a paragon of reliability at the best of times).

I'm currently stuck on a train delayed at HH, luckily the train aircon is working, I say lucky as it seems to think it's carrying a cargo of chilled meat....

 

[ChiefPlanner]

Key Route Strategy in old money - do not use a set of points if there is any chance of failure (applies in cold as well as hot weather) ....

Or in old BR terms "through routes only"

 

[MarkyT]

Key Route Strategy in old money - do not use a set of points if there is any chance of failure (applies in cold as well as hot weather) ....

Or in old BR terms "through routes only"

'Through routes' is also a term used in signalling "overrides", which are backup systems with reduced functionality to be used to remotely control a relay interlocking in the event of the primary telemetry at the panel signalbox failing. Overrides usually employ reed FDM (frequency division multiplex) techniques and always have a setting for 'all signals at red' and usually a setting for 'through routes', which for a particular station or junction would set the busiest and most useful routes through the location in the primary directions and set the signals to automatic working for all following trains. For a station with loop platforms like Totnes for example, through routes would set via the platforms so stopping trains could always call but clearly through trains would be checked for the loop turnouts as well but could nevertheless still run, albeit incurring some delay. At critical geographical junctions like Wootton Bassett, more complex 'selective overrides' were provided that could set the junction for both directions towards either South Wales or Bath. These backup systems were considered necessary because simply doubling up for redundancy on the primary telemetry using TDM (time division multiplex) would have been extraordinarily expensive in the early days of solid state electronics during the 1960s. As electronics got progressively cheaper and more reliable in subsequent decades, the TDMs were typically fully duplicated instead and the only override control provided, to cover complete system failure, was the 'all signals at red' control. Even modern screen based control centres today feature a completely independent means of safely replacing all signals to red for processor based interlockings such as SSI should the primary control screen interface become unusable.