Colwich Junction in the 1980s vs today

[Sean Emmett]

There has been some discussion re Euston - Glasgow record attempt that switching to the down 'slow' earlier could have saved useful seconds compared with sticking to the 'fast' and its 65 mph PSR.

 

[zwk500]

There has been some discussion re Euston - Glasgow record attempt that switching to the down 'slow' earlier could have saved useful seconds compared with sticking to the 'fast' and its 65 mph PSR.

Anybody suggesting so is wrong. The nearest Crossover is Lichfield North Junction, where DF-DS is 50mph, and then you're stuck on the DS which drops from 125EPS to 110 all trains just south of Rugeley TV, so you'd lose more time.

As it ran it had 125mph to Colwich, then 85->65mph at Colwich before back up to 100PSR thorugh Shrugborough.
Crossing earlier would have meant 125->50->125, then 110 for 3 miles before 90 through Colwich jn then the 100PSR through Shrugborough. Running DS from further back wouldn't have helped as the all-stations can't use the DF, and the DS has more speed restrictions south of Tamworth.

 

[GB]

The absence of flank protection has been responsible for a string of accidents, particularly in the 1990s. I've gone on about it at Ladbroke Grove before, which is a very comparable situation.

For the points at Colwich to have been set to the left seems a no-brainer. It doesn't have to be the whole crossover, just the facing points. If a Manchester train was being pulled up there it's unlikely that anything could get alongside it at full speed in the time available - but very likely that the reason it's being pulled up is an oncoming head-on movement on the Up Main. As happened. Any sensible risk assessment should have worked this out.

I thought things were so much better and more efficient during your era??

 

[jfollows]

Anybody suggesting so is wrong. The nearest Crossover is Lichfield North Junction, where DF-DS is 50mph, and then you're stuck on the DS which drops from 125EPS to 110 all trains just south of Rugeley TV, so you'd lose more time.

As it ran it had 125mph to Colwich, then 85->65mph at Colwich before back up to 100PSR thorugh Shrugborough.
Crossing earlier would have meant 125->50->125, then 110 for 3 miles before 90 through Colwich jn then the 100PSR through Shrugborough. Running DS from further back wouldn't have helped as the all-stations can't use the DF, and the DS has more speed restrictions south of Tamworth.

Exactly, thank you. This thread has become obsessive over the 65mph speed restriction. I calculate that the reduced speed over the 34 chains between the end of the EPS125 on the Down Trent Valley Fast and the resumption of line speed on the Down Main after the junction costs 10 seconds versus the parallel route from the Down Trent Valley Slow. Plus it's done on green signals throughout, no flashing yellows, no approach release, assuming the route ahead is clear of course. There's no alternative crossover route which would incur a penalty of less than ten seconds!
EDIT 34 chains (I originally said 24), but the calculation won't be far wrong. Or do your own modelling! But in very round terms, half a mile (40 chains) at 60mph takes 30 seconds whereas half a mile at 90mph takes 20 seconds.

 

[Watershed]

Exactly, thank you. This thread has become obsessive over the 65mph speed restriction. I calculate that the reduced speed over the 34 chains between the end of the EPS125 on the Down Trent Valley Fast and the resumption of line speed on the Down Main after the junction costs 10 seconds versus the parallel route from the Down Trent Valley Slow. Plus it's done on green signals throughout, no flashing yellows, no approach release, assuming the route ahead is clear of course. There's no alternative crossover route which would incur a penalty of less than ten seconds!
EDIT 34 chains (I originally said 24), but the calculation won't be far wrong. Or do your own modelling! But in very round terms, half a mile at 60mph takes 30 seconds whereas half a mile at 90mph takes 20 seconds.

It's probably rather more than 10 seconds, seeing as the train has to brake down for the speed restriction (in plenty of time to ensure that the TPWS and TASS don't get 'twitchy'), and then accelerate away again once the entire 200+m length has passed the end of the restriction.

But yes, despite the "Fast" line being slower than the "Slow" line at Colwich Jn, it's overall still faster to use the Fast Lines due to the preceding speed limits being higher.