Greenhill upper Diveunder back on'?

[QueensCurve]

This report in The Scotsman:-

http://www.scotsman.com/news/transport/edinburgh-glasgow-trains-every-ten-minutes-1-4009584

John McCormick, chairman of the Scottish Association for Public Transport, said: “A grade-separated Greenhill junction would improve reliability, but as the Network Rail document says, would also give the potential for six trains per hour on the Edinburgh-Glasgow line.

Is the prostpect of a grade-separated junction at Greenhill-Upper back on, or are they just extrapolating too far?

 

[Carntyne]

It's back as an option for CP6 & 7 I think.

 

[QueensCurve]

It's back as an option for CP6 & 7 I think.

Are there any preliminary designs for this available online?

 

[Class 170101]

It's back as an option for CP6 & 7 I think.

Seems to be a strange time to do it given that the junction will be wired this year. Hopefully passive provision has been made for Grade separation to happen later on.

 

[najaB]

Hopefully passive provision has been made for Grade separation to happen later on.

What could said provision entail other than not burying anything in the footprint of the future junction earthworks?

 

[Class 170101]

What could said provision entail other than not burying anything in the footprint of the future junction earthworks?

Masts in the right place so they don't need moving later.

I am sure Phillip Phloop could add other things.

 

[rebmcr]

What could said provision entail other than not burying anything in the footprint of the future junction earthworks?

Feeder stations, neutral sections, location of tensioners, etc.

 

[najaB]

Masts in the right place so they don't need moving later.

Feeder stations, neutral sections, location of tensioners, etc.

Thanks. Though with such a big potential change as a flying junction, unless the detailed design work has been done already it's hard to imagine that they'll get away without having to move/replace some equipment later on.

 

[Philip Phlopp]

Masts in the right place so they don't need moving later.

I am sure Phillip Phloop could add other things.

It's pointless trying to second guess the design of any diveunder - lots of variables to be taken into account which will dictate what goes where.

 

[Class 170101]

It's pointless trying to second guess the design of any diveunder - lots of variables to be taken into account which will dictate what goes where.

I thought grade separation at Greenhill was within the original remit of EGIP before de-scoping?

 

[najaB]

I thought grade separation at Greenhill was within the original remit of EGIP before de-scoping?

It was, but I would guess that not much detailed design work had been done up to that point.

 

[Railsigns]

It was, but I would guess that not much detailed design work had been done up to that point.

A detailed permanent way design had been produced, from which a signalling scheme plan was produced and signal sighting had been carried out.

 

[najaB]

A detailed permanent way design had been produced, from which a signalling scheme plan was produced and signal sighting had been carried out.

If they're still going ahead with that design then it should be possible to avoid major rework down the road.

 

[Railsigns]

If they're still going ahead with that design then it should be possible to avoid major rework down the road.

In theory, yes, but the designs will need to be updated to take account of changes to the existing junction layout since they were originally produced.

 

[Class 170101]

In theory, yes, but the designs will need to be updated to take account of changes to the existing junction layout since they were originally produced.

And I guess some standards may have changed since first designed.

 

[Railsigns]

And I guess some standards may have changed since first designed.

Yes; good point. The designs would be reviewed for compliance with the latest standards, which could lead to changes.

 

[MarkyT]

If the basic track and civils design for the diveunder has been carried out it should be possible to position the new signals required for electrification so as to to avoid having to re-space widely on the approaches for a subsequent grade separation project , even if the signals in the immediate vicinity of the junction may have to be reconfigured for new indications, or moved with the alignment. The new computer based controls will make subsequent changes far more practical than with the old relay systems nonetheless, so long as sufficient interlocking capacity and TFM addresses are safeguarded and appropriate gaps in signal and point numbers allocated for any additional facilities envisaged.

 

[Philip Phlopp]

I thought grade separation at Greenhill was within the original remit of EGIP before de-scoping?

We know where not to put things which will be expensive to move, but for run of the mill electrification components, masts and tensioners, they'll be moved as and when they need to be, and either reused or scrapped.

Just because a relatively detailed design exists also doesn't mean all the details about construction have been fully fleshed out.

There's not really any easy way to fully forward plan for flyovers or diveunders, because you need to provide access for construction piling rigs, cranes, diggers and delivery vehicles with forklifts etc. You don't want to be restricting overhead clearances or having to work around portal structures either on a major construction site, knock a mast and put the contact wire out of alignment and it's a dewirement that will result.

It's a bit different if the alignment and trackbed is prepared, and you don't need to get heavy plant in or you can use rail mounted kit, but for this and things like the talked about four tracking on the GWML around Swindon, trying to pre-empt what goes where and then building around it is not feasible.

 

[MarkyT]

We know where not to put things which will be expensive to move, but for run of the mill electrification components, masts and tensioners, they'll be moved as and when they need to be, and either reused or scrapped.

. . . It's a bit different if the alignment and trackbed is prepared, and you don't need to get heavy plant in or you can use rail mounted kit, but for this and things like the talked about four tracking on the GWML around Swindon, trying to pre-empt what goes where and then building around it is not feasible.

With conventional signalling as well, four tracking usually requires massive gantry structures for bidirectional running. Compare the existing four track section between Wantage Road and Challow with the double track sections. Hopefully ETCS will eventually reduce this expense in the future.