Was the HS2 Chiltern Tunnel necessary?

[titus]

Hi, non rail industry person here. Interested in what has gone wrong/right with HS2 so far.

Just wondering if anyone here could provide some insight as to if the Chiltern Tunnel and Colne Valley Viaducts were necessary from an engineering standpoint, or if they were primarily built to protect the ‘AONB’.

If we had not needed to worry about any NIMBYs, and had reduced the design speed from 400kph to 300kph, would there have been significantly cheaper routes through the region?

Many thanks

 

[John R]

The tunnels were built to overcome objections from local MPs, who have subsequently complained about both the initial and then ballooning cost of the project. It would clearly have been cheaper not to build them.

 

[Norm_D_Ploom]

Hi, non rail industry person here. Interested in what has gone wrong/right with HS2 so far.

Just wondering if anyone here could provide some insight as to if the Chiltern Tunnel and Colne Valley Viaducts were necessary from an engineering standpoint, or if they were primarily built to protect the ‘AONB’.

If we had not needed to worry about any NIMBYs, and had reduced the design speed from 400kph to 300kph, would there have been significantly cheaper routes through the region?

Many thanks

I don't think 400 to 300 would make much difference.
In fact even dropping it to 250 would probably still have an outturn cost very similar to what the final bill comes in at.

 

[titus]

The tunnels were built to overcome objections from local MPs, who have subsequently complained about both the initial and then ballooning cost of the project. It would clearly have been cheaper not to build them.

Hi thanks for getting back to me. This is what I had always assumed

 

[titus]

The tunnels were built to overcome objections from local MPs, who have subsequently complained about both the initial and then ballooning cost of the project. It would clearly have been cheaper not to build them.

Hi, thanks for getting back to me, that is what I had always assumed, that expensive concessions had to be made to a small number of conservative MPs as they were proceeding with such a narrow majority. But then I saw the 2010 labour command paper also planned significant tunnelling through the Chilterns even though labour had no MPs in that area. I therefore wondered if the was some actual structural reason it was necessary

 

[takno]

Hi, thanks for getting back to me, that is what I had always assumed, that expensive concessions had to be made to a small number of conservative MPs as they were proceeding with such a narrow majority. But then I saw the 2010 labour command paper also planned significant tunnelling through the Chilterns even though labour had no MPs in that area. I therefore wondered if the was some actual structural reason it was necessary

The Chilterns are hills. It would be surprising to see no tunnelling at all.

 

[LNW-GW Joint]

Some tunnelling would have been necessary through the Chilterns because of needing a nearly straight alignment (even for 250km/h).
Once you have committed a couple of shorter tunnels, the difference to a single 10-mile tunnel with the same TBMs won't have been enormous.
The Colne Valley viaduct was probably essential given the alignment chosen, to keep the railway away from built-up areas.
The Northolt tunnel is another matter of course, as its 13km is parallel to an existing 4-track railway formation (some of it disused).
But there would still have been major works at the road junctions (notably Hangar Lane), and the OOC end would have had to be in tunnel.
I see there is a view that the Bromford tunnel on the Birmingham branch avoided major surface work along the M6 corridor.
This tunnel was lengthened from the original plan.

I think HS2 have been quoted as saying that tunnelling is 2x the basic surface cost, and green tunnels (not much discussed) are x3.
I doubt the route chosen had anything to do with truculent MPs of any persuasion, though the most outspoken (Cheryl Gillan) was a Tory cabinet minister.

 

[edwin_m]

The gradient profile for the viaduct and southern tunnel portal is at https://assets.publishing.service.g...2305b8e982/C222-ATK-CV-DPP-020-000001-FPD.pdf. This also shows the passive provision for the Heathrow spur, which I think has now been deleted but may have been a factor in defining the elevation in this area. But despite this, it's difficult to see how a viaduct or an embankment across the lakes could have been avoided, except by going underneath it which would probably have made a single tunnel all the way from the Chilterns to Old Oak Common. Or taking a radically different route that would avoid the area completely.

The plan shows a ground cover of 30m a short distance into the Chiltern tunnel. The plans and profiles of the rest of the tunnel are on https://www.gov.uk/government/publi...f-commons-select-committee-2016-country-south. These show similar ground cover over much of the length, as well as a gradients up to 2.5% which probably prevent Birmingham-bound trains getting to maximum speed. The ground profile and the contours on the plans also show how the ground level varies above the tunnel (significantly more than it does immediately to the north). Vertical and longitudinal scales are different so the slopes shown are ten times steeper than reality, but nevertheless it's obvious that a surface route on a similar horizontal alignment would have needed a lot of earthworks and viaducts.

 

[HSTEd]

In the technical sense, it would have been possible to build a railway through the Chilterns outside of a tunnel.

But the earthworks and viaducts would be rather impressive and probably not that much cheaper than building the tunnel.

As HS2 have found to their cost, attempting to build stuff in AONBs has definite political and schedule costs - they can't be ignored.
Solving engineering problems is much easier than solving political ones.

I personally take the view that we'd probably have been better off just putting the entirety of Phase 1 in tunnel and eating the extra technical costs. It would have rendered the project far less politically toxic to do so. The political fallout (especially from Swampy et al) has cost HS2 a substantial sum of money. I'm not sure how succesful the Green tunnels hve been in that regard, either.

 

[bleeder4]

I think that when it is up and running between London and Birmingham, only around 8 minutes of the 45 minute journey will actually be above ground.

 

[snowball]

I think that when it is up and running between London and Birmingham, only around 8 minutes of the 45 minute journey will actually be above ground.

How do you arrive at that figure?

 

[Energy]

HS2 was always being optimistic having gone above ground through one of the widest bits of the Area of Oustanding Natural Beauty.

(This image is old and not up to date, but gives an idea to HS2s positioning within AONB)



They’d have been better either following the M40, or heading up towards Tring and expecting to tunnel, or parallel the WCML, from the start.

 

[GRALISTAIR]

As HS2 have found to their cost, attempting to build stuff in AONBs has definite political and schedule costs - they can't be ignored.
Solving engineering problems is much easier than solving political ones.

I love that quote. Great way to phrase it.

 

[Bletchleyite]

In short, no. The WCML doesn't "pollute" the bit of the Chilterns it goes through, and nor would HS2. Crikey, even the M6 doesn't really spoil the Lune Gorge, though the railway is barely noticeable in comparison.

It was an utter waste of money.

 

[bnc2018]

To be fair, the Chilterns is a defined area of outstanding natural beauty and it is quite hilly. If we were going to cut tunnels out of HS2, we would definitely start with the green tunnels.

The Chipping Warden and Greatworth tunnels are both enormous undertakings for seemingly very little benefit at all.

 

[GRALISTAIR]

In short, no. The WCML doesn't "pollute" the bit of the Chilterns it goes through, and nor would HS2. Crikey, even the M6 doesn't really spoil the Lune Gorge, though the railway is barely noticeable in comparison.

It was an utter waste of money.

I am biased because I love railways and argue that a railway - even electrified actually adds to the beauty and often you get wildlife very close by. The Lune Gorge is a classic example whereas the M6 is a blot and eyesore on the landscape. I think HS2 will prove the same in years to come. Tunneling added to the cost.

 

[titus]

In the technical sense, it would have been possible to build a railway through the Chilterns outside of a tunnel.

But the earthworks and viaducts would be rather impressive and probably not that much cheaper than building the tunnel.

As HS2 have found to their cost, attempting to build stuff in AONBs has definite political and schedule costs - they can't be ignored.
Solving engineering problems is much easier than solving political ones.

I personally take the view that we'd probably have been better off just putting the entirety of Phase 1 in tunnel and eating the extra technical costs. It would have rendered the project far less politically toxic to do so. The political fallout (especially from Swampy et al) has cost HS2 a substantial sum of money. I'm not sure how succesful the Green tunnels hve been in that regard, either.

In the technical sense, it would have been possible to build a railway through the Chilterns outside of a tunnel.

But the earthworks and viaducts would be rather impressive and probably not that much cheaper than building the tunnel.

As HS2 have found to their cost, attempting to build stuff in AONBs has definite political and schedule costs - they can't be ignored.
Solving engineering problems is much easier than solving political ones.

I personally take the view that we'd probably have been better off just putting the entirety of Phase 1 in tunnel and eating the extra technical costs. It would have rendered the project far less politically toxic to do so. The political fallout (especially from Swampy et al) has cost HS2 a substantial sum of money. I'm not sure how succesful the Green tunnels hve been in that regard, either.

Thanks for answer, completely agree that for a single project standpoint it’s often easier just to do one complex bit of engineering, than a bunch of complex political negotiations. Though I guess I personally come at this from a more political than engineering standpoint and would first focus on fundamentally reforming political/planning system.

If that could be solved then we wouldn’t have to have complex engineering each time and in long run would be better

I think for critical pieces of national infrastructure main-lines/motorways/400kv-grid, central government should be able to override local government with little consultation, whereas for all the rest, we should empower local governments to make their own decisions on infrastructure spending, procurement and planning.

That way you would have less bureaucracy fighting between central and local. And more competition between the regions.

 

[stuu]

I think that when it is up and running between London and Birmingham, only around 8 minutes of the 45 minute journey will actually be above ground.

I think you mean 8 minutes will have an actual view, the rest being in tunnels or cuttings, a lot of which are engineered to hide the line, rather than being necessary from an engineering standpoint.

The green tunnels, especially the Copthall tunnel near Denham, are a total waste of money and resources, as are a lot of the earthworks to hide the railway. They must have added a fortune to the cost

 

[HSTEd]

I think for critical pieces of national infrastructure main-lines/motorways/400kv-grid, central government should be able to override local government with little consultation, whereas for all the rest, we should empower local governments to make their own decisions on infrastructure spending, procurement and planning.

Local Government is not the issue though, local people are.

Attempting to impose this project will just get you Twyford Down after Twyford Down.
The political fallout from attempting to suppress protests of that scale could seriously damage national governments, let alone their party members in local government.

Britain is not a society, especially in the era of social media, where you can just crush major dissent like that.

If they had just bored the tunnel the anti HS2 gang would be complaining about one or two dozen access points the size of large houses. They'd have nothing like the traction they have with the aerial photography of giant (even if temporary) scars on the landscape and ancient forests felled.

EDIT:
Alternatively they could have done like HS1 and hugged a motorway, either the M40 or the M1.

 

[furnessvale]

The Chilterns are hills. It would be surprising to see no tunnelling at all.

High speed lines in other countries go uphill and down dale only using tunnels when absolutely necessary. This saves an absolute fortune but the UK has nimbys to appease.

 

[GRALISTAIR]

High speed lines in other countries go uphill and down dale only using tunnels when absolutely necessary. This saves an absolute fortune but the UK has nimbys to appease.

Other countries do too, but the UK seems to be the worst!

 

[HSTEd]

Other countries do too, but the UK seems to be the worst!

NIMBYs are pretty powerful in other countries with succesful high speed rail systems.

In Japan they are currently holding up the construction of the Chuo Shinkansen and succesfully forced the abandonment of the Narita Shinkansen.
Indeed, Japanese railways are increasingly resorting to tunnels to avoid such problems.

 

[titus]

Local Government is not the issue though, local people are.

Attempting to impose this project will just get you Twyford Down after Twyford Down.
The political fallout from attempting to suppress protests of that scale could seriously damage national governments, let alone their party members in local government.

Britain is not a society, especially in the era of social media, where you can just crush major dissent like that.

If they had just bored the tunnel the anti HS2 gang would be complaining about one or two dozen access points the size of large houses. They'd have nothing like the traction they have with the aerial photography of giant (even if temporary) scars on the landscape and ancient forests felled.

EDIT:
Alternatively they could have done like HS1 and hugged a motorway, either the M40 or the M1.

I get it might not possible to go quite as far as I would like, but ultimately I think since the 1970s, most developed countries have tipped the scales much too far in giving small groups NIMBYs far to much power to prevent important construction projects.

And I think there’s too much resignation to ‘That’s just the way it is’ when it could actually be reformed through courageous governance that was not just thinking in short term. Ultimately Tyford Down is a footnote in the history of a road that is used by hundreds of thousands every day.

 

[HSTEd]

I get it might not possible to go quite as far as I would like, but ultimately I think since the 1970s, most developed countries have tipped the scales much too far in giving small groups NIMBYs far to much power to prevent important construction projects.

And I think there’s too much resignation to ‘That’s just the way it is’ when it could actually be reformed through courageous governance that was not just thinking in short term. Ultimately Tyford Down is a footnote in the history of a road that is used by hundreds of thousands every day.

On the other hand, noone will remember the money that was saved by using these politically fraught, but notionally less expensive, solutions either.
The impacts of the railway on the landscape (and any destruction of forests dating to time immemorial) will endure forever.

 

[titus]

On the other hand, noone will remember the money that was saved by using these politically fraught, but notionally less expensive, solutions either.
The impacts of the railway on the landscape (and any destruction of forests dating to time immemorial) will endure forever.

I would argue the percentage of land and forest used by major national infrastructure projects is tiny, especially compared to the amount used for say, agriculture. And as I said, other than in a few national projects, I would advocate for giving more direct control over most planning decisions directly to local governments and communities.

And I think people will remember the money saved. If you capital expenditure is 30% more efficient over a long period of time, the amount of economically and socially beneficial infrastructure you can build over that time will increase exponentially as you can reinvest the gains, and improve people’s lives.

 

[Bald Rick]

High speed lines in other countries go uphill and down dale only using tunnels when absolutely necessary. This saves an absolute fortune but the UK has nimbys to appease.

Famously, the original LGV-SE had no tunnels at all.

Also, famously, it started about 20 miles from Gare du Lyon, roughly the equivalent of HS2 starting at the M25.

 

[masekwm]

The green tunnels that hide the track from nothing or past a car storage site are a complete waste of money. You can't see the tunnel under construction from the road in this photo, so why they're encasing it in concrete and then covering it is a mystery to me.

 

[Geogregor]

The green tunnels that hide the track from nothing or past a car storage site are a complete waste of money. You can't see the tunnel under construction from the road in this photo, so why they're encasing it in concrete and then covering it is a mystery to me.

This tunnel is the most ludicrous example overengineering HS2 to appease NIMBYs

 

[Nottingham59]

The other aspect to remember is that, surprisingly, building tunnels is not the biggest cost incurred by HS2.

The main civil engineering contract C1 to build the Chiltern tunnels and the Colne Valley viaduct (22km of line), was awarded in July 2017 to the ALIGN Joint Venture for a cost of £965 million. That's £44m per route km.

At that rate per km, a twin-track tunnel all the way from the portal at Euston direct to Birmingham Interchange (147km) would have cost £6.5 billion. Even allowing for construction inflation since 2017, the outturn cost today of a London-Birmingham tunnel would have been of the order of £10-£12bn.

It's easy to blame unnecessary tunnelling costs on the ballooning cost of HS2, but it's more complicated than that.
Personally I don't understand where the money has gone. And HS2 and DfT seem very reluctant to publish sufficiently detailed accounts to explain how the whole project is going to cost around £250M per route km.

See: https://www.rendel-ltd.com/news/view/align-consortium-is-awarded-a-flagship-hs2-civil-works-contract

 

[stuu]

The main civil engineering contract C1 to build the Chiltern tunnels and the Colne Valley viaduct (22km of line), was awarded in July 2017 to the ALIGN Joint Venture for a cost of £965 million. That's £44m per route km.

Yes but the ever so wise government let the contracts on a cost-plus basis, so the actual cost is likely to be considerably higher