Cambridge South new station construction progress.

[Bald Rick]

Concievably I suppose but my view would be they need to either get on with EWR or have some appropriate idea of how EWR will interface with the existing railway and provide for appropriately.

It would be nice if EWR and Cambridge South were completed at the same time but I can't see that happening with our disjointed thinking.

It’s not disjointed thinking at all. EWR to Cambridge is a long way away, if at all. Cambridge South is funded, and close to starting the consents process. It would be farcical to delay Cambridge South for several years waiting for a railway that may not even happen.

Would be interested in your thought process @Bald Rick?

What @Ianno87 said. With the timetable as it is the platforms must be paired by direction to enable trains at close headway to stop.

 

[edwin_m]

What @Ianno87 said. With the timetable as it is the platforms must be paid by direction to enable trains at close headway to stop.

Yes, with the short section of four-tracking currently proposed pairing by use would introduce two flat junction conflicts close together, cancelling out the benefit of the four tracks.

However if ultimately Shepreth Branch to Cambridge is four-tracked with no grade separation at Shepreth Branch (so with a western pair for Kings Cross and EWR and an eastern pair for Liverpool Street), I'd like to think that the platforms can be re-purposed to this configuration without a major rebuilding of what is being planned now.

 

[Class 170101]

However if ultimately Shepreth Branch to Cambridge is four-tracked with no grade separation at Shepreth Branch (so with a western pair for Kings Cross and EWR and an eastern pair for Liverpool Street), I'd like to think that the platforms can be re-purposed to this configuration without a major rebuilding of what is being planned now.

This is exactly what I am thinking. (Now where is the like button).

 

[adamedwards]

I would assume, as EWR is supposed to go on to Norwich and Ipswich, the EWR junction ought to fly over the KX lines and connect into the Liverpool St lines, paired by route as suggested. EWR then run into Cambridge platforms 7&8 and on to Ely/Newmarket. There would probably be a single line from EWR into the KX lines in case of emergencies and to allow early morning and late evening trains into the south end bays. That way we minimise conflict and reduce the points and crossings, which trades off against the cost of the bridges.

 

[edwin_m]

I would assume, as EWR is supposed to go on to Norwich and Ipswich, the EWR junction ought to fly over the KX lines and connect into the Liverpool St lines, paired by route as suggested. EWR then run into Cambridge platforms 7&8 and on to Ely/Newmarket. There would probably be a single line from EWR into the KX lines in case of emergencies and to allow early morning and late evening trains into the south end bays. That way we minimise conflict and reduce the points and crossings, which trades off against the cost of the bridges.

However the KX trains also run onwards towards Ely and would probably be at least as frequent as the EWR train, so it's not possible to separate all conflicting movements without at least two flyovers and possibly yet another island at Cambridge.

It really depends on whether EWR joins the Royston line somewhere west of Shepreth Branch Junction and therefore has to share those tracks for a distance, in which case (if Shepreth Branch Junction isn't grade-separated) it clearly lands up on the western pair through Cambridge South. I tend to think this is the most likely option. Other options where EWR joins either the Liverpool Street line south of Shepreth Branch Junction, or the line north of there, might open up alternative junction layouts.

As none of this is decided yet, it's sensible for Cambridge South to adopt the most straightforward four-track layout with the proviso that it can be remodeled later.

 

[DynamicSpirit]

What @Ianno87 said. With the timetable as it is the platforms must be paid by direction to enable trains at close headway to stop.

So who was it who got the platforms to join the union?

Yes, with the short section of four-tracking currently proposed pairing by use would introduce two flat junction conflicts close together, cancelling out the benefit of the four tracks.

However if ultimately Shepreth Branch to Cambridge is four-tracked with no grade separation at Shepreth Branch (so with a western pair for Kings Cross and EWR and an eastern pair for Liverpool Street), I'd like to think that the platforms can be re-purposed to this configuration without a major rebuilding of what is being planned now.

My guess is that E-W rail would force grade separation at the junction - and on a quick look at Google maps, I don't see any obvious problems building a grade separated junction where the lines diverge.

Assuming Cambridge South station is built with two island platforms - which I would kinda expect on cost grounds - Keeping the platforms as paired by direction has the advantage for passengers of all northbound trains for the same destination leaving from the same island. (And ditto for London-bound trains, though that may be less important since people heading for London are more likely to want a particular train rather than just grabbing the first one to arrive).

 

[Bald Rick]

So who was it who got the platforms to join the union?

Oops

 

[Ianno87]

So who was it who got the platforms to join the union?



My guess is that E-W rail would force grade separation at the junction - and on a quick look at Google maps, I don't see any obvious problems building a grade separated junction where the lines diverge.

Unforunately, Google's Aerial maps are a little out of date in this area...

 

[edwin_m]

So who was it who got the platforms to join the union?

There was a bridge strike and the platforms came out in sympathy.

My guess is that E-W rail would force grade separation at the junction - and on a quick look at Google maps, I don't see any obvious problems building a grade separated junction where the lines diverge.

Assuming Cambridge South station is built with two island platforms - which I would kinda expect on cost grounds - Keeping the platforms as paired by direction has the advantage for passengers of all northbound trains for the same destination leaving from the same island. (And ditto for London-bound trains, though that may be less important since people heading for London are more likely to want a particular train rather than just grabbing the first one to arrive).

Unforunately, Google's Aerial maps are a little out of date in this area...

I don't think grade separation would be easy at the junction itself, as a ramp on the Royston line would probably reach to a road overbridge and one on the Stortford line would probably reach a level crossing. Also both lines have adjacent housing and people would object to incursion on their gardens or to elevated tracks blocking their light and view.

The open section between the junction and Addenbrookes Road is more than 1km so might be possible. Or is that where the maps are out of date?

 

[Ianno87]

The open section between the junction and Addenbrookes Road is more than 1km so might be possible. Or is that where the maps are out of date?

The "vee" of the junction in now pretty much filled with housing.

 

[bspahh]

The "vee" of the junction in now pretty much filled with housing.

Abberley Wood is only shown for about half its length on the map, but the housing is there on the aerial photograph, which was last updated in May 2020.
Abberley Wood, Great Shelford, Google Maps

 

[edwin_m]

The "vee" of the junction in now pretty much filled with housing.

I think the area west and north of the junction is more critical. The curve on the Royston line could then be tightened a bit so the tracks from Royston didn't quite touch at the junction. They could then continue to curve off to the west where the Up line would ramp up, swing back east over the tracks from Stortford, and drop down to be level with and just east of the Up line towards Stortford before Addenbrookes Road.

However, as mentioned above, this still leaves quite a bit of conflict in the Cambridge station area and I'm still not convinced there would be much operational benefit over a paired-by-use arrangement with no grade separation. I think the benefit to passengers from having all trains in the same direction on the same island is small in this case. Most of the trains going beyond Cambridge North will be running via Royston so would always be at the westernmost platform, and as mentioned I think most London travellers will wait for a train to their preferred terminus rather than taking whichever comes first. So it's only really passengers for Cambridge (central) and Cambridge North who have to pick a platform.

 

[DynamicSpirit]

I think the area west and north of the junction is more critical. The curve on the Royston line could then be tightened a bit so the tracks from Royston didn't quite touch at the junction. They could then continue to curve off to the west where the Up line would ramp up, swing back east over the tracks from Stortford, and drop down to be level with and just east of the Up line towards Stortford before Addenbrookes Road.

Yeah, that's kinda how I'd think of doing it.

However, as mentioned above, this still leaves quite a bit of conflict in the Cambridge station area and I'm still not convinced there would be much operational benefit over a paired-by-use arrangement with no grade separation.

That's where it gets interesting - and somewhat dependent on what the post-EW-rail pattern of services is. Most plausibly you'll have some trains from both sides of the junction in Great Shelford terminating at Cambridge and some trains from both sides of the junction heading further North (Stansted-Birmingham, Kings X-Kings Lynn and perhaps Oxford-Norwich). Off the top of my head, I would have thought that the way to avoid most conflicts from that would be to have grade separation at Great Shelford, have the tracks paired by direction, and have Cambridge itself set up as 4-track, with terminators terminating on the inside tracks, while the through trains continue on the outside tracks. I'd imagine anything else, whether paired by direction or use, will inevitably cause lots of conflicts.

One other thing... if you go for paired by use, that forces you to 4-track all the way from Shelford to Cambridge. I'm guessing that if you went for grade separated junction/paired by direction, then that might allow you to keep to the currently planned 2 tracks just splitting for Cambridge South station.

 

[edwin_m]

That's where it gets interesting - and somewhat dependent on what the post-EW-rail pattern of services is. Most plausibly you'll have some trains from both sides of the junction in Great Shelford terminating at Cambridge and some trains from both sides of the junction heading further North (Stansted-Birmingham, Kings X-Kings Lynn and perhaps Oxford-Norwich). Off the top of my head, I would have thought that the way to avoid most conflicts from that would be to have grade separation at Great Shelford, have the tracks paired by direction, and have Cambridge itself set up as 4-track, with terminators terminating on the inside tracks, while the through trains continue on the outside tracks. I'd imagine anything else, whether paired by direction or use, will inevitably cause lots of conflicts.

One other thing... if you go for paired by use, that forces you to 4-track all the way from Shelford to Cambridge. I'm guessing that if you went for grade separated junction/paired by direction, then that might allow you to keep to the currently planned 2 tracks just splitting for Cambridge South station.

Snag being that Cambridge effectively only has three through tracks. One of them is long enough for two trains split by a scissors crossover but it connects into one of the others part way along its length, which makes it much less useful than if it had connected to a non-platform track. Adding a fourth through track would involve losing both through roads (one would become the platform track) and at least one of the carriage sidings to the east to build a new island.

The other issue is the two south-facing bays to the west. With paired by direction any train leaving these would have to cross over both Down tracks and, if heading to EWR, the Up track for Stortford to reach the Up track for Royston. The importance of this one depends how many EWR or other trains would terminate in Cambridge and are short enough to use these platforms.

 

[mr_jrt]

Time for an application of the time-honoured technique of cutting a building off at the foundations and sliding it out of the way? Move it a few metres and those bays can become two more through platforms.

(...and no, I'm not being serious)

 

[cle]

Realistically, will there be more than 2-3tph from EWR? Plus some freight.

Cambridge North also has room to build more platforms and turn trains, if 'Central' isn't an option, and another island to the east. That might lessen use of the bays (and move to all LivSt/Shelford to Cambridge North (Ely/KL peaks), and Royston/EWR only in the bays).

 

[edwin_m]

Realistically, will there be more than 2-3tph from EWR? Plus some freight.

Cambridge North also has room to build more platforms and turn trains, if 'Central' isn't an option, and another island to the east. That might lessen use of the bays (and move to all LivSt/Shelford to Cambridge North (Ely/KL peaks), and Royston/EWR only in the bays).

How that would work, unless the freight terminal whose access tracks pass between the station building and the platforms is no longer required? It would also add trains to the two-track section between Central and North, including the Newmarket line junction and a level crossing.

 

[cle]

The two track section isn't too bad, it's three until Newmarket Junction (nearly) - and again at North which has additional room for platforms/passenger lines.

 

[dk1]

The two track section isn't too bad, it's three until Newmarket Junction (nearly) - and again at North which has additional room for platforms/passenger lines.

its only two track Cambridge to Coldham Lane Jcn. The third line is just the down Goods Loop which is often used for stabling purposes. It's not a passenger line except in emergency situations.

 

[cle]

Yes I am assuming that it could be upgraded as part of these wider Cambridge works. Not wholly outlandish or ambitious, given what EWR is doing

 

[edwin_m]

There'd still be a two-track bottleneck between the station and the start of the goods loop, unless it was possible to get another track under Mill Road bridge. If that could be done then a flexible three-track layout might have some benefit in allowing parallel moves by Newmarket trains, especially if they run through to EWR instead of crossing the layout to access the west side bays. But the two track section from there to North station doesn't look feasible to widen.

 

[TheDavibob]

How that would work, unless the freight terminal whose access tracks pass between the station building and the platforms is no longer required? It would also add trains to the two-track section between Central and North, including the Newmarket line junction and a level crossing.

Think it's worth flagging up that the freight terminal is earmarked for development, via Phase 4 of this project. Still very early stages of planning, though.

Removal of the freight terminal would make replacing the westernmost track with a platform relatively straightforward as far as I can tell. Crayons coming out here, but I don't think it would require *that* much work (relatively speaking) to make Platform 3 the up through platform and Platform 2 a reversing platform, which would allow higher frequency reversals, though presumably with a penalty for the (relatively few) through services.

 

[cle]

There'd still be a two-track bottleneck between the station and the start of the goods loop, unless it was possible to get another track under Mill Road bridge. If that could be done then a flexible three-track layout might have some benefit in allowing parallel moves by Newmarket trains, especially if they run through to EWR instead of crossing the layout to access the west side bays. But the two track section from there to North station doesn't look feasible to widen.

That’s a very fair point, in agreement. And good shout on EWR to Ipswich if that comes to fruition. I’d imagine that the goods line being upgrade to bi-di passenger quality would be helpful enough. From a passenger POV, I can only imagine 2tph max in each direction.

Maybe 3tph one day, but I’d suspect the EWR would become the second tph for the main stations. Plus if Ipswich-Peterborough ever got to hourly (which Soham will support) - that also adds capacity east of the split.

 

[Steve Harris]

There'd still be a two-track bottleneck between the station and the start of the goods loop, unless it was possible to get another track under Mill Road bridge. If that could be done then a flexible three-track layout might have some benefit in allowing parallel moves by Newmarket trains, especially if they run through to EWR instead of crossing the layout to access the west side bays. But the two track section from there to North station doesn't look feasible to widen.

Isn't that what is already happening? I thought a third track was being put under Mill Road to gain access to the new carriage sidings adjacent to the station.

 

[edwin_m]

Isn't that what is already happening? I thought a third track was being put under Mill Road to gain access to the new carriage sidings adjacent to the station.

I'm not familiar with what's going on there, but if it's a siding access it may not also be useable as a running line, which is what would be needed to create a three-track section.

 

[Steve Harris]

I'm not familiar with what's going on there, but if it's a siding access it may not also be useable as a running line, which is what would be needed to create a three-track section.

I think you might need to take a look at https://www.railforums.co.uk/threads/mill-road-cambridge-bridge-shut-in-2019.170880/

 

[edwin_m]

That link mentions it's an access track for a wash plant, so probably not a running line.

 

[Steve Harris]

That link mentions it's an access track for a wash plant, so probably not a running line.

Indeed.

I am familiar with what is going on in Cambridge. I even walked over said bridge last month.
And I can tell you that you won't get anymore lines under Mill Road without major investment and probably a new bridge as there just isn't the room currently for more lines.

 

[edwin_m]

Indeed.

I am familiar with what is going on in Cambridge. I even walked over said bridge last month.
And I can tell you that you won't get anymore lines under Mill Road without major investment and probably a new bridge as there just isn't the room currently for more lines.

Thanks for the confirmation - so the idea of three running lines out of the main station towards Cambridge North is a non-starter.

 

[Steve Harris]

Thanks for the confirmation - so the idea of three running lines out of the main station towards Cambridge North is a non-starter.

Correct.