How would you remodel Ely North Junction and surrounding lines?

[tatitiliti]

I think one of the biggest issues is the two-track convergence between Ely North Junction and Ely station. I think for anything to work, you’d have to find a way of having a third rail for this stretch, possibly dedicated for the Ipswich branch passenger services and freight and linked to a fourth platform at Ely.

Keen to learn your thoughts about how you would you deal with improving this and the junction bottleneck itself?

 

[ac6000cw]

This subject has been discussed at great length before, see:

Ely North Junction upgrade alternatives

Moderator note: Split from https://www.railforums.co.uk/threads/ely-north-junction-upgrade-proposals.68376/ "level crossing work" might mean a number of bridges over railways and rivers, rather than replacing a few barriers Which indeed it does, and as such the chances of it ever getting the...

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Ely North Junction upgrade proposals

http://www.cambridge-news.co.uk/Ely/4m-boost-to-rail-network-thanks-to-EU-10072012.htm "Almost £4 million of EU funding will be put towards upgrading the Ely North Junction. The European Parliament agreed to invest £3.8 million in the major scheme today (Tuesday). It comes just a week after the...

www.railforums.co.uk

Could Ely North Junction be grade separated?

Moderator note: Split from https://www.railforums.co.uk/threads/ely-north-junction-upgrade-proposals.68376/ General observation on the proposals. There are various options for a new road to avoid the Queen Adelaide level crossings. Options 2 and 3 - the Northern and Long Southern by-passes -...

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I think one of the biggest issues is the two-track convergence between Ely North Junction and Ely station. I think for anything to work, you’d have to find a way of having a third rail for this stretch,

I disagree - I think it's the junction conflicts at both ends of the Ely area, the level crossings at Queen Adelaide which straddle all three routes at the north end, and the 20 mph speed restrictions across both river bridges north of the station for loco-hauled trains (which mean that a long freight can't exceed that from when the front reaches the first bridge until the tail of it has cleared the second one. For a typical 750m+ intermodal train that's a fair amount of time, especially for a northbound via the east-side loop that has to cross and hence block the whole layout north of the station).

If you want a third track, run it from the Soham line northwards then fly it over the Norwich and Kings Lynn lines north of North Jnc. to a grade-separated junction with the March line. That would keep most of the freight out of the Ely pinch/conflict points.

 

[Magdalia]

Before people get their crayons out, bear in mind that a superficial look at Ely on a map or aerial photo ignores the real challenges, which are below the surface.

The Fens are a peat bog that expands and contracts according to the weather. Right now it is shrinking because we have had almost no rain for 2 months and the peat is drying.

For most of the existing railway, solid rock is a long way down, This means that it is very difficult to build anything too heavy to float on the peat, especially any bridges and viaducts made of concrete. The piles for the Ely bypass viaduct are reputed to be a third of the height of the Ely Cathedral tower. In particular this means that grade separation in the Fens would be very very expensive, because the standard ways of doing grade separation, with lots of concrete, won't work in the Fens.

Drainage is critical. Most of the land is below sea level. This means that the main watercourses are higher than the surrounding land, and held in by big earth banks (what the other side of the pond would be called levees).

One consequence of all of this is that most roads cross the railway on the level, because it is too difficult and expensive to build road bridges. This includes the three crossings virtually next to each other at Queen Adelaide, but the most challenging is probably Kiln Lane, which is between Ely and Ely North Junction.

 

[zwk500]

I think one of the biggest issues is the two-track convergence between Ely North Junction and Ely station. I think for anything to work, you’d have to find a way of having a third rail for this stretch, possibly dedicated for the Ipswich branch passenger services and freight and linked to a fourth platform at Ely.

Keen to learn your thoughts about how you would you deal with improving this and the junction bottleneck itself?

I disagree with a third track between Ely and Ely north Junction, but that's because I'd build a completely separate freight bypass of Ely to the east, including curves to King's Lynn and Norwich, closing the west loop and a bypass for Queen Adelaide level crossings (buying up the properties in the middle). The King's Lynn line would then be given two tracks through the junction so you'd have a conventional double junction for Peterborough/King's Lynn with the extra single line to Norwich.
Image below shows this (completely fantasy) ides, Black - existing, red - new track, blue - closed section, Pink, new road to avoid level crossings. The curves to Lynn/Norwich could be omitted if there's sufficient room released in Ely station to runround the freights that would use these curves.

There's not a chance in hell it would ever get funding.

 

[Maltazer]

Does it even really need these kinds of hugely expensive interventions though (whether official proposals or crayon versions)?

If you stand on a platform at Ely there will be no trains for ages and then they all turn up at once - maybe there’s scope to play with the timetable, even if it meant the odd train standing in a platform for 5 mins to make it work?

Add in some repairs to get freight speeds up to at least 50mph, and maybe a layout change so moves between platform 3 and the Soham line don’t conflict with platform 2 - maybe that could be enough?

 

[zwk500]

Does it even really need these kinds of hugely expensive interventions though (whether official proposals or crayon versions)?

Depends what timescales you're looking at. Getting freight to bypass Ely essentially eliminates the problem from coming back again in 5 or 10 years time. If you're not building the curves, an easier alignment is probably available by following the bypass to the east of the town. Retention of the West Loop in that case would probably be necessary through.

If you stand on a platform at Ely there will be no trains for ages and then they all turn up at once - maybe there’s scope to play with the timetable, even if it meant the odd train standing in a platform for 5 mins to make it work?

There is not scope to play with the timetable (at least not significantly). Ely sits at the centre of a ring of constraints. Cambridge, the Felixstowe Branch, Peterborough, the King's Lynn single line sections, etc.

Add in some repairs to get freight speeds up to at least 50mph, and maybe a layout change so moves between platform 3 and the Soham line don’t conflict with platform 2 - maybe that could be enough?

Whilst you could do the layout change (not convinced the alignment permits any higher freight speeds), it doesn't really release much capacity as the constraints are the single line to Soham and the conflicts at Ely North Junction.

 

[tatitiliti]

I disagree with a third track between Ely and Ely north Junction, but that's because I'd build a completely separate freight bypass of Ely to the east, including curves to King's Lynn and Norwich, closing the west loop and a bypass for Queen Adelaide level crossings (buying up the properties in the middle). The King's Lynn line would then be given two tracks through the junction so you'd have a conventional double junction for Peterborough/King's Lynn with the extra single line to Norwich.
Image below shows this (completely fantasy) ides, Black - existing, red - new track, blue - closed section, Pink, new road to avoid level crossings. The curves to Lynn/Norwich could be omitted if there's sufficient room released in Ely station to runround the freights that would use these curves.
View attachment 180110
There's not a chance in hell it would ever get funding.

That’s a really interesting idea that had crossed my mind and I think would solve a lot of the issues - shame that it would be so eyewateringly expensive!

Having said that, even if you didn’t have any grade separation with King’s Lynn and Norwich lines and just had points, it may still solve a lot of problems.

 

[Brubulus]

Given that most of the project is actually a road project to mitigate level crossing risk, the railway project is effectively just removing the single leads, with little new track and no grade separation. There is a cheaper solution to the road aspect and that is an ANPR solution. This involves upgrading the track between Queen Adelaide way and Prickwillow Road, enabling 1 level crossing closure, then placing ANPR cameras on the other two to attempt to prevent through traffic. This would then close 1 crossing, and massively reduce traffic at the other 2, clearly leading to an overall reduction in level crossing risk, while also having a very low cost compared to road bridges in the Fens.

 

[zwk500]

That’s a really interesting idea that had crossed my mind and I think would solve a lot of the issues - shame that it would be so eyewateringly expensive!

Having said that, even if you didn’t have any grade separation with King’s Lynn and Norwich lines and just had points, it may still solve a lot of problems.

If you wanted to avoid the cost of grade separation, I'd go around the east of Ely following the bypass.

 

[Nottingham59]

For most of the existing railway, solid rock is a long way down, This means that it is very difficult to build anything too heavy to float on the peat, especially any bridges and viaducts made of concrete. The piles for the Ely bypass viaduct are reputed to be a third of the height of the Ely Cathedral tower. In particular this means that grade separation in the Fens would be very very expensive, because the standard ways of doing grade separation, with lots of concrete, won't work in the Fens.

I thought those piles were two thirds of the height of Ely tower. And that's 66m. But are 44m piles really that expensive? All you need to do is keep going until you reach the required resistance. I'd be surprised if the cost of piling was a such a significant fraction of the cost of building a railway viaduct.

 

[30907]

If you wanted to avoid the cost of grade separation, I'd go around the east of Ely following the bypass.

The map shows it going round the south and west of the city - is that what you mean?

 

[zwk500]

The map shows it going round the south and west of the city - is that what you mean?

Sorry yes, getting directionality mixed up! Essentially - option 1 is as shown on my sketch, option 2 would be round the other side!

 

[Magdalia]

I do think that it is time to start again with upgrading Ely.

The genesis of the existing proposal was some EU funding in 2012, see the start of this discussion:

Ely North Junction upgrade proposals

http://www.cambridge-news.co.uk/Ely/4m-boost-to-rail-network-thanks-to-EU-10072012.htm "Almost £4 million of EU funding will be put towards upgrading the Ely North Junction. The European Parliament agreed to invest £3.8 million in the major scheme today (Tuesday). It comes just a week after the...

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I think that the last public consultation on the existing proposals were in 2021, and it has been in the long grass for nearly 4 years now.

Given that most of the project is actually a road project to mitigate level crossing risk, the railway project is effectively just removing the single leads, with little new track and no grade separation.

I agree with this assessment.

Over that period a lot has changed.

• the UK has left the EU
• war in Ukraine and tariffs are disrupting global trade, the era of globalisation is generally recognised to be over
• the high tech industries in and around Cambridge have expanded rapidly (in 2012 the Biomedical Campus was still fields)
• Cambridge North opened in 2017 and Cambridge South will open in 2026
• Ely southern bypass and the Kings Dyke bridge have demonstrated the challenges of trying to build big concrete infrastructure in the Fens

Freight is no longer the priority that it was in 2012. Globalisation is probably reaching its high water mark, one of the major container operators pulling a lot of its traffic out of Felixstowe earlier this year was a straw in the wind. I have always been sceptical about the UK spending its scarce investment pot on projects where the main beneficiaries are manufacturers in China and tech giants in the USA, who would be enabled to get imported goods into the UK more cheaply.

I am also sceptical that lots of road flyovers in the Fens for not much traffic is a good use of the UK scarce investment funding pot. If we are going to be building roads there are a lot of other places with higher priority. Given the choice, I suspect that the residents of Ely would much rather have some improvements to the A10 than a flyover at Queen Adelaide.

The focus now needs to be much more on passenger capacity, especially in and out of Cambridge. Fortunately the Kings Lynn line has already demonstrated what needs to be done here: the answer for more passenger capacity is longer trains. It is bonkers that, when paths through Ely are a major capacity constraint, that so many of those scarce train paths are taken up by 2, 3 and 4 car trains.

My priority would be lengthening platforms to allow for longer trains, recognising that the biggest engineering challenge here is probably Stansted Airport. As some will have noted from elsewhere, I also advocate breaking the Stansted-Birmingham and Norwich-Liverpool trains at Peterborough. One of the advantages of this is that it reduces the timetabling constraints at Ely.

Having been a beneficiary of the Hitchin flyover, I can empathise with those that feel that any significant rail investment at Ely should include some grade separation. In management generally, a good way to make progress is to do the relatively simple things that yield a lot of benefit. For this reason my priority would be to grade separate the Peterborough and Kings Lynn lines. This can be done on "terra firma" by building a grade separated junction near Clayway crossing, between Ely West Junction and Chettisham, which is on the Isle of Ely, not in the Fens. The only building on the Fen would be 1-2 miles of new railway to link up with the existing Kings Lynn line near where the River Lark flows into the River Great Ouse. The 1-2 miles of existing line from Ely North Junction going towards Littleport would be closed, including removal of the single lead junction. This might create some space for a ramp onto a road bridge over the Peterborough line at Queen Adelaide, though I'm not sure where it would land on the western side of the line.

There is a cheaper solution to the road aspect and that is an ANPR solution.

This is an interesting bit of lateral thinking, though I'm not confident it would work. Road access isn't just about Queen Adelaide, the route via the 3 level crossings is also the main route between Ely and Prickwillow, and the alternatives are long diversions, especially for vehicles too high to use the underbridge at Ely station. I suspect that APNR at Queen Adelaide might lead to more bridge strikes at Ely!

But are 44m piles really that expensive? All you need to do is keep going until you reach the required resistance. I'd be surprised if the cost of piling was a such a significant fraction of the cost of building a railway viaduct.

If lots of piles are required then yes. For example, compare the amount of concrete, including piling that you can't see, in the Ely Southern bypass, with what would be needed for a structure like the Hitchin flyover. For 44m deep piles that is a lot of concrete that has to be paid for. The Ely Southern bypass was about 35% over budget, mainly because of piling. A grade separated junction in the Fens would need deep piles, and lots of them. Then there are the issues of whether the structures are stable once they have been completed, see Kings Dyke.

 

[Brubulus]

I do think that it is time to start again with upgrading Ely.

The genesis of the existing proposal was some EU funding in 2012, see the start of this discussion:

Ely North Junction upgrade proposals

http://www.cambridge-news.co.uk/Ely/4m-boost-to-rail-network-thanks-to-EU-10072012.htm "Almost £4 million of EU funding will be put towards upgrading the Ely North Junction. The European Parliament agreed to invest £3.8 million in the major scheme today (Tuesday). It comes just a week after the...

www.railforums.co.uk

I think that the last public consultation on the existing proposals were in 2021, and it has been in the long grass for nearly 4 years now.


I agree with this assessment.

Over that period a lot has changed.

• the UK has left the EU
• war in Ukraine and tariffs are disrupting global trade, the era of globalisation is generally recognised to be over
• the high tech industries in and around Cambridge have expanded rapidly (in 2012 the Biomedical Campus was still fields)
• Cambridge North opened in 2017 and Cambridge South will open in 2026
• Ely southern bypass and the Kings Dyke bridge have demonstrated the challenges of trying to build big concrete infrastructure in the Fens

Freight is no longer the priority that it was in 2012. Globalisation is probably reaching its high water mark, one of the major container operators pulling a lot of its traffic out of Felixstowe earlier this year was a straw in the wind. I have always been sceptical about the UK spending its scarce investment pot on projects where the main beneficiaries are manufacturers in China and tech giants in the USA, who would be enabled to get imported goods into the UK more cheaply.

I am also sceptical that lots of road flyovers in the Fens for not much traffic is a good use of the UK scarce investment funding pot. If we are going to be building roads there are a lot of other places with higher priority. Given the choice, I suspect that the residents of Ely would much rather have some improvements to the A10 than a flyover at Queen Adelaide.

The focus now needs to be much more on passenger capacity, especially in and out of Cambridge. Fortunately the Kings Lynn line has already demonstrated what needs to be done here: the answer for more passenger capacity is longer trains. It is bonkers that, when paths through Ely are a major capacity constraint, that so many of those scarce train paths are taken up by 2, 3 and 4 car trains.

My priority would be lengthening platforms to allow for longer trains, recognising that the biggest engineering challenge here is probably Stansted Airport. As some will have noted from elsewhere, I also advocate breaking the Stansted-Birmingham and Norwich-Liverpool trains at Peterborough. One of the advantages of this is that it reduces the timetabling constraints at Ely.

Having been a beneficiary of the Hitchin flyover, I can empathise with those that feel that any significant rail investment at Ely should include some grade separation. In management generally, a good way to make progress is to do the relatively simple things that yield a lot of benefit. For this reason my priority would be to grade separate the Peterborough and Kings Lynn lines. This can be done on "terra firma" by building a grade separated junction near Clayway crossing, between Ely West Junction and Chettisham, which is on the Isle of Ely, not in the Fens. The only building on the Fen would be 1-2 miles of new railway to link up with the existing Kings Lynn line near where the River Lark flows into the River Great Ouse. The 1-2 miles of existing line from Ely North Junction going towards Littleport would be closed, including removal of the single lead junction. This might create some space for a ramp onto a road bridge over the Peterborough line at Queen Adelaide, though I'm not sure where it would land on the western side of the line.


This is an interesting bit of lateral thinking, though I'm not confident it would work. Road access isn't just about Queen Adelaide, the route via the 3 level crossings is also the main route between Ely and Prickwillow, and the alternatives are long diversions, especially for vehicles too high to use the underbridge at Ely station. I suspect that APNR at Queen Adelaide might lead to more bridge strikes at Ely!


If lots of piles are required then yes. For example, compare the amount of concrete, including piling that you can't see, in the Ely Southern bypass, with what would be needed for a structure like the Hitchin flyover. For 44m deep piles that is a lot of concrete that has to be paid for. The Ely Southern bypass was about 35% over budget, mainly because of piling. A grade separated junction in the Fens would need deep piles, and lots of them. Then there are the issues of whether the structures are stable once they have been completed, see Kings Dyke.

Grade separation just isn't worth it, any sort of new railway line in the Fens is just too expensive and not a good use of scarce resources, especially if freight demand will weaken, an assesment I don't agree with, especially if getting lorries off the roads is remotely a priority, so enabling another freight path is an absolute must, though there are limits other than Ely (Felixstowe and Haughley Junction) Regarding train lengths, I agree that the Stansted-Birmingham and Norwich-Liverpool services aren't long enough. Maybe TFW and GBR could order a fleet of 6 car intercity standard FLIRTs for MK4 replacement, Stansted-Birmingham, Nottingham-Cardiff, Norwich-Liverpool and other regional express routes dealing with elderly or under capacity rolling stock. However Kings Lynn, Norwich and Peterborough all want 2tph to Cambridge, though I'm not sure of the economic basis for Norwich, especially since Thetford isn't really much of a satellite town of Cambridge, especially when compared with Bury St Edmunds, Kings Lynn or March.

The ANPR solution involves a road upgrade to enable the closure of Prickwillow LC, so Prickwillow road can still access Ely via the low bridge, while taller vehicles will have to use the bypass. It will only delay people accessing the northern suburbs of Ely, not the whole town unless in a tall vehicle.

 

[Magdalia]

Grade separation just isn't worth it

Grade separation can be worth it, as Hitchin and Werrington have demonstrated.

any sort of new railway line in the Fens is just too expensive and not a good use of scarce resources

I'm almost in full agreement, but the big advantage of Clayway is that it is on Isle of Ely Terra Firma, not in the Fens, so would only be about as expensive as any other grade separation.

However Kings Lynn, Norwich and Peterborough all want 2tph to Cambridge, though I'm not sure of the economic basis for Norwich, especially since Thetford isn't really much of a satellite town of Cambridge, especially when compared with Bury St Edmunds, Kings Lynn or March.

Experience on the Kings Lynn line shows that 2tph peak and 1tph off peak with long trains works well. Having seen how things have gone since 2020 on the Kings Lynn line, I don't see any justification for 2tph all day.

I'd agree that, with regard to the intermediate stations, the Norwich line does not have as much Cambridge traffic as the Kings Lynn line or the Peterborough line. I see the Peterborough-Cambridge service as the priority for more capacity. The Norwich line could get most of what it needs by a judicious reallocation of a small number of train paths from East Midlands to Greater Anglia at the peak times for travel to and from Cambridge.

The ANPR solution involves a road upgrade to enable the closure of Prickwillow LC, so Prickwillow road can still access Ely via the low bridge, while taller vehicles will have to use the bypass. It will only delay people accessing the northern suburbs of Ely, not the whole town unless in a tall vehicle.

The Fens are primarily an agricultural area, farmers use tall vehicles a lot to move stuff about. I don't know how much agricultural traffic uses the Queen Adelaide route, it isn't an obvious route for beet traffic to Wissington or Bury St Edmunds, but a tractor towing a trailer loaded with straw bales isn't going under the bridge at Ely, and probably isn't wanted on the bypass either.

 

[Class 170101]

The line between Ely and Peterborough already is double track and allows for parallel moves over Ely North Junction. The restriction at Ely North Jn is between Ely and Kings Lynn and Ely and Norwich which are single leads.

The line used to be double towards Kings Lynn, Peterborough and Norwich but from what I read it was quite a slow junction?

 

[dk1]

The line between Ely and Peterborough already is double track and allows for parallel moves over Ely North Junction. The restriction at Ely North Jn is between Ely and Kings Lynn and Ely and Norwich which are single leads.

The line used to be double towards Kings Lynn, Peterborough and Norwich but from what I read it was quite a slow junction?

The direct (priority) route was towards Norwich. This changed to Peterborough in 1992. Didn’t sign it then so couldn’t comment on each line speed.

 

[Class 170101]

The direct (priority) route was towards Norwich. This changed to Peterborough in 1992. Didn’t sign it then so couldn’t comment on each line speed.

Wow, very surprised, I would have expected it to be Kings Lynn or Peterborough pre 1992, never Norwich.

 

[Magdalia]

The line used to be double towards Kings Lynn, Peterborough and Norwich but from what I read it was quite a slow junction?

The direct (priority) route was towards Norwich. This changed to Peterborough in 1992. Didn’t sign it then so couldn’t comment on each line speed.

The 1947 LNER Sectional Appendix has:

Norwich line 45 mph
Kings Lynn line 40 mph
Peterborough line 25 mph

For London-Norwich the Cambridge route was on equal footing with the Ipswich route until dieselisation. Kings Lynn was mostly served by portions detaching from/attaching to Norwich trains at Ely.

And much of the traffic between Cambridge and March ran via St Ives not Ely, especially the freight.

 

[dk1]

Wow, very surprised, I would have expected it to be Kings Lynn or Peterborough pre 1992, never Norwich.

It was all historical. The GE eventually became the prime route to Norwich.

== Doublepost prevention - post automatically merged: 18 May 2025 ==

The 1947 LNER Sectional Appendix has:

Norwich line 45 mph
Kings Lynn line 40 mph
Peterborough line 25 mph

For London-Norwich the Cambridge route was on equal footing with the Ipswich route until dieselisation. Kings Lynn was mostly served by portions detaching from/attaching to Norwich trains at Ely.

And much of the traffic between Cambridge and March ran via St Ives not Ely, especially the freight.

Thank you. Exactly how the splitting distants set the routes up.

 

[bspahh]

If lots of piles are required then yes. For example, compare the amount of concrete, including piling that you can't see, in the Ely Southern bypass, with what would be needed for a structure like the Hitchin flyover. For 44m deep piles that is a lot of concrete that has to be paid for. The Ely Southern bypass was about 35% over budget, mainly because of piling. A grade separated junction in the Fens would need deep piles, and lots of them. Then there are the issues of whether the structures are stable once they have been completed, see Kings Dyke.

Some of the budget over run for the Ely Southern bypass was just the expense of the extra concrete needed to be used for the piling. I suspect that quite a lot of the expense was from scheduling problems from the delays. If the mayor had not been quite so keen on getting the project started, they could have done the ground investigations, and then had time to update the plan, which would have been a lot cheaper. They might have even been able to save some cash by adjusting the design.

I haven't seen much in the Ely local press about some of the negative impacts. At the moment, freight trains trundle past the riverside area at 20mph. If there are more freight trains, and they are passing at 50mph, it will be quite a lot louder.

 

[Magdalia]

Exactly how the splitting distants set the routes up.

As a child my favourite signal was the combined Ely North down advanced starter/Ely North Junction down distant, which was between the 2 river bridges and visible from the north end of the station platforms.

This was a trident of colour lights, but only the middle one ever showed red. If the advanced starter was cleared it showed 3 yellow lights, one for each route at Ely North Junction, and in a diagonal line with Norwich on the right the highest. If any route was cleared at Ely North Junction, then that route got a green light, while the other 2 routes remained at yellow.

 

[dk1]

As a child my favourite signal was the combined Ely North down advanced starter/Ely North Junction down distant, which was between the 2 river bridges and visible from the north end of the station platforms.

This was a trident of colour lights, but only the middle one ever showed red. If the advanced starter was cleared it showed 3 yellow lights, one for each route at Ely North Junction, and in a diagonal line with Norwich on the right the highest. If any route was cleared at Ely North Junction, then that route got a green light, while the other 2 routes remained at yellow.

Yes I recall that signal. Got a good view from the front seats on a 105.

 

[Magdalia]

Yes I recall that signal. Got a good view from the front seats on a 105.

Yes, though, for me, those units will only ever be Cravens!

If you were really lucky the trident signal would change as the train approached.

 

[MarkyT]

Here's my suggestion showing the railway in aqua blue and north and east bypasses in yellow.


The track and signalling layout

 

[Maltazer]

Resurrecting this again after re-reading the various grade separation ideas.

What if the existing junctions remain, but with addition of a single track flyover for passenger trains only, headed for Kings Lynn (if space permitted it could potentially branch off to the Norwich down line too, but let’s ignore that for now)

If the sand train (or any other freight) still crossed on the flat, how short could a flyover reasonably be, given the power of a modern EMU?

 

[Bald Rick]

If the sand train (or any other freight) still crossed on the flat, how short could a flyover reasonably be, given the power of a modern EMU?

Maximum gradient permitted in 2.5%*, which is 1:40. Assuming no constraints with signalling / pointwork etc, and a 7 metre rail to rail height difference, a 20-30 metre level span (on the skew) and allowing a for the 4 vertical curves, you are looking at something like 800 metres at best.

* for high speed passenger lines it is 3.5%, if derogation could be got for that it reduce it by around 150 metres.

 

[Magdalia]

Maximum gradient permitted in 2.5%*, which is 1:40. Assuming no constraints with signalling / pointwork etc, and a 7 metre rail to rail height difference, a 20-30 metre level span (on the skew) and allowing a for the 4 vertical curves, you are looking at something like 800 metres at best.

* for high speed passenger lines it is 3.5%, if derogation could be got for that it reduce it by around 150 metres.

Thanks, these are interesting numbers.

How much of that 800 metres would be earthworks, and how much concrete viaduct, in a grade separation on "normal" terrain? How would that be different on a Fenland peat bog with unstable ground conditions? How many concrete piles would be required per 100 metres of viaduct?

By way of comparison, I reckon that the Hitchin flyover is about 600 metres long, and has at least 20 pairs of concrete piles.

 

[Maltazer]

Thanks, these are interesting numbers.

How much of that 800 metres would be earthworks, and how much concrete viaduct, in a grade separation on "normal" terrain? How would that be different on a Fenland peat bog with unstable ground conditions? How many concrete piles would be required per 100 metres of viaduct?

By way of comparison, I reckon that the Hitchin flyover is about 600 metres long, and has at least 20 pairs

Given the restricted space I’d think the entire thing would need to be bridge with no embankments.

 

[Bald Rick]

How much of that 800 metres would be earthworks, and how much concrete viaduct, in a grade separation on "normal" terrain? How would that be different on a Fenland peat bog with unstable ground conditions? How many concrete piles would be required per 100 metres of viaduct?

That all depends on the site, how much space there is, the angles, and ground conditions.

The difference in cost between concrete viaduct and embankment isn’t that much, even with big piling.