edwin_m
Veteran Member
From https://www.railforums.co.uk/thread...fication-progress.83452/page-244#post-3528948
The problem there is that even that small amount of eletrification would trigger the signalling immunisation mentioned, because the return currents find their way into nearby tracks as well. Although it was recently re-signalled they have left most of the trackside equipment unchanged for the time being so it isn't currently (!) immune. The plan seems to be to do it Reading-style, having got a computerised interlocking the trackside equipment can be changed over in stages as the layout is re-modelled. However all of this will need doing before electrification arrives by any route.
A quick win might be to wire Filton to platforms 13 and 15 (the ones normally used by Paddington trains) at Temple Meads while it's closed for four-tracking (I wish they'd called it requadrification!). It's only about five miles (20 track miles, 10 if you just did the Mains) and would enable the PR boost of electric trains all the way. Bristol East Junction would have to be redone eventually but in the overall scheme of things the 'waste' would be minimal.
The problem there is that even that small amount of eletrification would trigger the signalling immunisation mentioned, because the return currents find their way into nearby tracks as well. Although it was recently re-signalled they have left most of the trackside equipment unchanged for the time being so it isn't currently (!) immune. The plan seems to be to do it Reading-style, having got a computerised interlocking the trackside equipment can be changed over in stages as the layout is re-modelled. However all of this will need doing before electrification arrives by any route.