Salisbury - Exeter punctuality improvements?

[Kite159]

Are those sections in the right place to help make the service reliable? Do down trains typically get held waiting for an up at Tisbury?

Yep.

 

[Zomboid]

Yep.

In which case it's Tisbury platform 2 that's needed

 

[PTR 444]

The big problem with rebuilding the bridge is that the next junction north on the M5 is miles away at Cullompton - the old A38 just wouldn't be able to cope if you closed the motorway entirely. It would have to be done by by alternately closing each carriageway.

Surely the official diversion route for M5 traffic would be up the A30 to Honiton, then A303 to Ilminster and A358 back to M5 Junction 25?

Only Exeter - Cullompton traffic would then need to use the old A38, as the A377/A396 route can cater for the Exeter - Tiverton/North Devon flow.

 

[Harpo]

I would start by finding out the facts, the real root causes of delay, and addressing them.

Otherwise spending billions on incredibly expensive upgrades alone without investigation only gives you a shinier railway to run your late trains on.

 

[The Ham]

I would start by finding out the facts, the real root causes of delay, and addressing them.

Otherwise spending billions on incredibly expensive upgrades alone without investigation only gives you a shinier railway to run your late trains on.

Indeed, although there are some areas where other factors come to play. For example the desire to improve service frequency for the Devon Metro would mean that redoubling west of Honiton didn't only give you a "shinier railway" but also give you more services.

Also, arguably, there's an argument that (given the cost to make changes) it's potentially better value to create as long a section of double track as you can before the next big cost comes into play rather than just the minimum to create a loop.

For example, if you've got the fixed costs of a set of signals at each end and the associated trackwork, it's better to build it (say) 5km long than 500m long. As that's likely to reduce the impact of more of the delays yet the cost wouldn't be anywhere near as much as 10 times there amount even though the distance is.

Over the long term one single 5km loop may even be cheaper and provide nearly as many benefits as 2 loops of 500m.

 

[Harpo]

Also, arguably, there's an argument that (given the cost to make changes) it's potentially better value to create as long a section of double track as you can before the next big cost comes into play rather than just the minimum to create a loop.

So long as it doesn’t deliver (like many rationalisations did) inflexible timetabling options. ‘Ossification’ used to be the BS Bingo word for that.

 

[The Ham]

So long as it doesn’t deliver (like many rationalisations did) inflexible timetabling options. ‘Ossification’ used to be the BS Bingo word for that.

Indeed, however I did start my post by agreeing that it had to be evidence lead, which was why I was suggesting that a single longer loop may be better than two shorter ones - although in the context of evidence lead improvements (i.e. it may not be).

 

[Zomboid]

would start by finding out the facts, the real root causes of delay, and addressing them.

Agree, but there's value in resilience enhancements so that when delays do occur they can be mitigated and don't snowball.

In the current timetable it looks like trains are generally scheduled to pass at Pinhoe, Axminster, Sherborne and Tisbury. And Tisbury seems an obvious candidate to cause delays to snowball with the station just off the loop so any delayed up train has to decelerate, stop, do it's station business and accelerate away before a down can do anything. Putting the station on a loop would mean that as soon as the up clears the single line, the down can go Notch 8 and should be delayed less, or might even avoid it entirely.