Carstairs junction bypass

[adamedwards]

Watching a driver's view video I was struck by how slow the speed limit is on the curve taken by trains heading from Carlisle to Edinburgh. 15mph on the curve and 30 on the junctions. So let's imagine a bypass of this running further south with a flying junction to the West Coast Main Line. It would save a good few minutes on the journey. How much money can be justified peer minute saved?

 

[Senex]

Watching a driver's view video I was struck by how slow the speed limit is on the curve taken by trains heading from Carlisle to Edinburgh. 15mph on the curve and 30 on the junctions. So let's imagine a bypass of this running further south with a flying junction to the West Coast Main Line. It would save a good few minutes on the journey. How much money can be justified peer minute saved?

The Float Jn to Lampits Jn alignment is still there, turning right away from the Glasgow line just after the river-bridge and then heading off dead straight towards Edinburgh. But it looks as if you'd not get a really fast junction by turning out north of the river. You'd need to ease the junction-curve and provide a new Clyde bridge, but you'd get the advantage of being able to get the junction on a straight and possibly for full speed on both lines. Ah well, wishful thinking ....

 

[adamedwards]

We could call it HS4!

 

[Tobbes]

The Float Jn to Lampits Jn alignment is still there, turning right away from the Glasgow line just after the river-bridge and then heading off dead straight towards Edinburgh. But it looks as if you'd not get a really fast junction by turning out north of the river. You'd need to ease the junction-curve and provide a new Clyde bridge, but you'd get the advantage of being able to get the junction on a straight and possibly for full speed on both lines. Ah well, wishful thinking ....

As an adjunct to HS2, this could be valuable in limiting the time losses on classic-compatible services to Edinburgh (given that they will not tilt, IIUC). Better would be to build it in such a way as to allow HS2 Ph 3 - (HSR from Crewe - Edinburgh/Glasgow) to use it as well.

 

[adamedwards]

Indeed, which helps add to the case to build it. I guess it might also then increase speeds on the Glasgow line by removing points from the curve at the south junction.

 

[Gathursty]

I was surprised that the north part of the Carstairs triangle is only single track when I passed through earlier this year.

 

[markymark2000]

The Float Jn to Lampits Jn alignment is still there, turning right away from the Glasgow line just after the river-bridge and then heading off dead straight towards Edinburgh. But it looks as if you'd not get a really fast junction by turning out north of the river. You'd need to ease the junction-curve and provide a new Clyde bridge, but you'd get the advantage of being able to get the junction on a straight and possibly for full speed on both lines. Ah well, wishful thinking ....

Even if not a fast junction, you could save a good few minutes on there when you work out from top line speed down to 15 and then back up to line speed the other side. Just a modest 50 would save a lot of time.

 

[Bald Rick]

Watching a driver's view video I was struck by how slow the speed limit is on the curve taken by trains heading from Carlisle to Edinburgh. 15mph on the curve and 30 on the junctions. So let's imagine a bypass of this running further south with a flying junction to the West Coast Main Line. It would save a good few minutes on the journey. How much money can be justified peer minute saved?

The difficulty is where the junction is. One train an hour would benefit from it, two an hour post HS2. And the trains aren’t particularly full.

A cut off on the old alignment might save 2-3 minutes if the junction is 60mph, and then only if the timetable permits it each end (there’s no point saving 3 minutes if the train then has to wait 3 minutes at Haymarket East for the only available path).