How do these circuits ensure coverage of all tracks? Looking at Filton Bank (four tracks), I can only see
3S60 passing over it once today. Will it pass over a different track on subsequent days?
There is no requirement to cover all track, NR use a risk based system so it’s more likely the worst line is protected.
Unfortunately, there is not enough circuits or equipment to cover all lines sufficiently. The overall strategy is to cover as much as possible, linearly. For example, it’s much more beneficial to cover London to Bletchley on two lines than it is to do all four lines between London and Watford.
There are exceptions to this rule, the MML circuit covers all lines between Kentish Town and Bedford but this is rare and uses a lot of time and paths which is why this is done at night.
