There are two very good reasons why trains don't run when the lines are flooded - neither of which are to do with trains not being able to run through standing water.
The first and most common is due to the way signalling systems work. Almost all rail lines use track circuits to detect the presence of trains on sections of track. Basically the wheels and axles of the train are used to complete a circuit between the two rails. Unfortunately dirty floodwater will also complete the circuit, and as it is a fail-safe system all the signals will default to red.
The second reason is that in cases of extreme flooding there is a possibility that the roadbed on which the rails are laid may be washed-out, in which case trains simply can't run safely.
Under the RSSB rule book trains can technically be run through flooding, however severe restrictions are placed on operations. Full details can be found here and here.
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The first and most common is due to the way signalling systems work. Almost all rail lines use track circuits to detect the presence of trains on sections of track. Basically the wheels and axles of the train are used to complete a circuit between the two rails. Unfortunately dirty floodwater will also complete the circuit, and as it is a fail-safe system all the signals will default to red.
The second reason is that in cases of extreme flooding there is a possibility that the roadbed on which the rails are laid may be washed-out, in which case trains simply can't run safely.
Under the RSSB rule book trains can technically be run through flooding, however severe restrictions are placed on operations. Full details can be found here and here.
Glad you got home okay in the end though.