HS2 phase 1 tunnel boring plan

[Ironside]

I found an article on the tunnelling plans for hs2 phase 1.

http://tunneltalk.com/UK-high-speed-rail-28Oct2014-HS2-procurement-and-TBM-drive-strategy.php

Procurement for the major civils contracts for HS2 is expected to begin at the end of this month (September 2015).


Alistair Cowan, for HS2, told TunnelTalk: “Pre-qualification questionnaires for £6.4 billion of civils contracts, divided into seven packages ranging from £700m to £1bn, will be sent out later this month.”

The procurement timeline now envisages invitations to tender in Spring 2016, followed by the award of contracts later in 2016 or early 2017. This will be timed to follow the granting of Royal Assent for the hybrid bill that is currently proceeding through UK Parliament. Construction of the major civils, including tunnelling is scheduled to begin in 2018.

It is understood that the originally-planned three contracts in the South section have been merged into two larger lots, and it is these that incorporate most of the twin running TBM-bored tunnels for the first phase of HS2.

These include the 7km tunnel out of Euston Station, the 14km Northolt tunnel in the east of the capital, and the 16km Chiltern tunnel from the M25 through Buckinghamshire.

 

[gordonthemoron]

isn't Northolt in the west of London?

 

[Phil.]

isn't Northolt in the west of London?

Northolt is in the county of Middlesex which is to the west of London. It doesn't have a London postcode.

 

[Clip]

Northolt is in the county of Middlesex which is to the west of London. It doesn't have a London postcode.

Middlesex doesn't exist now does it? Lots of Greater London doesn't have a London postcode. And both the tube and railway station are within the zones too

 

[Bigfoot]

These include the 7km tunnel out of Euston Station, the 14km Northolt tunnel in the east of the capital, and the 16km Chiltern tunnel from the M25 through Buckinghamshire.

I think this is why the questioning has arisen...

 

[Tio Terry]

Plan is to drop TBM's in to a box at Old Oak Common working in opposite directions, one pair towards Euston, others towards the North.

 

[tsangpogorge]

I keep hearing that the new line will run through extensive tunnels starting in west London, through the Chilterns and under south Manchester to name some examples. Does this not increase journey times because of speed restrictions that will need to be imposed because of heat dissipation issues, potential derailment when trains pass each other and tunnel boom in urban areas?

 

[Ironside]

I keep hearing that the new line will run through extensive tunnels starting in west London, through the Chilterns and under south Manchester to name some examples. Does this not increase journey times because of speed restrictions that will need to be imposed because of heat dissipation issues, potential derailment when trains pass each other and tunnel boom in urban areas?

There will be pairs of tunnels, one track in each direction. They will also be of a wide enough diameter so that there won't be any heat dissapation or drag problems that will limit the speed.

 

[tsangpogorge]

There will be pairs of tunnels, one track in each direction. They will also be of a wide enough diameter so that there won't be any heat dissapation or drag problems that will limit the speed.

The maximum speed under the channel which also has up and down trains in separate tunnels is 99mph, are they simply not wide enough for high speed running?

 

[TheKnightWho]

The maximum speed under the channel which also has up and down trains in separate tunnels is 99mph, are they simply not wide enough for high speed running?

I think that's for timetabling with the shuttles.

 

[NotATrainspott]

The maximum speed under the channel which also has up and down trains in separate tunnels is 99mph, are they simply not wide enough for high speed running?

The Channel Tunnel was designed for the services which run through it: Eurostar, freight and the vehicle shuttle services. Freight and vehicle shuttles are speed limited just like they would be on the surface for reasons not related to them being in a tunnel. The fastest services are the Eurostars but as there is no way for them to overtake slower freight services, there would be little point in them running much faster than 160km/h. As there would be no point running faster, the infrastructure (e.g. the tunnel horizontal and vertical curve radii) hasn't been designed to allow speeds to be any higher either.

The HS2 tunnels will be for exclusive use by HS2 trains, so there's no problem running them much faster. All TBM-built tunnels will have a single track per tunnel bore, with an emergency cross-passage linking the two tunnels every four hundred metres so that if there is a fire, passengers would be evacuated to the non-incident bore. At 230km/h this single bore is of 7m diameter but due to aerodynamic effects, the faster tunnels have larger diameters. The 400km/h tunnels under Crewe will have a 10m diameter, for instance.

 

[tsangpogorge]

The Channel Tunnel was designed for the services which run through it: Eurostar, freight and the vehicle shuttle services. Freight and vehicle shuttles are speed limited just like they would be on the surface for reasons not related to them being in a tunnel. The fastest services are the Eurostars but as there is no way for them to overtake slower freight services, there would be little point in them running much faster than 160km/h. As there would be no point running faster, the infrastructure (e.g. the tunnel horizontal and vertical curve radii) hasn't been designed to allow speeds to be any higher either.

The HS2 tunnels will be for exclusive use by HS2 trains, so there's no problem running them much faster. All TBM-built tunnels will have a single track per tunnel bore, with an emergency cross-passage linking the two tunnels every four hundred metres so that if there is a fire, passengers would be evacuated to the non-incident bore. At 230km/h this single bore is of 7m diameter but due to aerodynamic effects, the faster tunnels have larger diameters. The 400km/h tunnels under Crewe will have a 10m diameter, for instance.

Thanks for the explanation, I was about to ask why Eurostar trains are restricted to 230km/h in the second section of HS1 which runs mostly underground but you saved me the trouble!

 

[NotATrainspott]

Thanks for the explanation, I was about to ask why Eurostar trains are restricted to 230km/h in the second section of HS1 which runs mostly underground but you saved me the trouble!

HS1 Phase 2, from Northfleet Junction to St Pancras, was designed to have a maximum speed of 230km/h because it would have only saved a few minutes to increase the maximum speed above that

 

[Phil.]

Middlesex doesn't exist now does it? Lots of Greater London doesn't have a London postcode. And both the tube and railway station are within the zones too

Northolt still isn't London.

 

[Clip]

Northolt still isn't London.

You best tell that to the London borough of Ealing which its part of then.

 

[LNW-GW Joint]

The maximum speed under the channel which also has up and down trains in separate tunnels is 99mph, are they simply not wide enough for high speed running?

At some point the tunnel spec was reduced to 160kph to save money during the fit-out (on things like OHLE, power supplies and track quality).
It also turned out that a higher speed was not practicable because of the speed differential with the Eurotunnel shuttles, which are limited to 140kph.
If Eurostars went any faster it would actually reduce the capacity of the tunnel unless they were flighted one after the other, and there aren't enough services to need that.

 

[TheKnightWho]

At some point the tunnel spec was reduced to 160kph to save money during the fit-out (on things like OHLE, power supplies and track quality).
It also turned out that a higher speed was not practicable because of the speed differential with the Eurotunnel shuttles, which are limited to 140kph.
If Eurostars went any faster it would actually reduce the capacity of the tunnel unless they were flighted one after the other, and there aren't enough services to need that.

It's why we need a channel road tunnel to get rid of the shuttles

 

[Ianno87]

It's why we need a channel road tunnel to get rid of the shuttles

..and Eurostar fares would go up as there would be fewer other trains to be contributing towards paying track access charges. That, and the fact were sort-of stuck with a tunnel engineered for 100mph only now...

 

[najaB]

It's why we need a channel road tunnel to get rid of the shuttles

If a rail tunnel struggles to pay its way, a road tunnel would be even less likely to break even.

 

[GRALISTAIR]

If a rail tunnel struggles to pay its way, a road tunnel would be even less likely to break even.

I just cant see with all the environmental issues etc, how a road tunnel will ever get built now -even if the cars were all electric (thank god by the way)

 

[HSTEd]

A drive through crossing would have been far more likely to pay its way than the current solution, in hindsight.

It would have destroyed all the Channel ferries and led to serious economic integration in a way that shuttles will never enable.
But the security nuts would never have liked a drive through crossing of any type - but I hope any eventual Irish Sea crossing is built with a drive through element a la Great Belt, otherwise it simply wouldn't be worth it.

 

[najaB]

A drive through crossing would have been far more likely to pay its way than the current solution, in hindsight.

On the other hand it would have been more expensive (additional ventilation requirements), would have been slower to cross (speeds would probably be limited to around 50mph), could be paralysed by one broken-down vehicle and wouldn't have enabled any additional through journeys (how many people would drive to Paris?).

 

[edwin_m]

And if a drive-through crossing had driven all the ferries out of business what would happen if it had to be closed because of, say, a vehicle fire? Which would be a far more frequent and dangerous event than in the more controlled surroundings of Eurotunnel. Even fairly detailed checks on each vehicle (=more delay) won't identify for certain any that are at risk of bursting into flames, especially as a fire could result from a RTA or from a terrorist making use of the contents of their fuel tank.

Running through the Tunnel at 186mph instead of 100mph would only save about 3min.

 

[HSTEd]

On the other hand it would have been more expensive (additional ventilation requirements), would have been slower to cross (speeds would probably be limited to around 50mph), could be paralysed by one broken-down vehicle and wouldn't have enabled any additional through journeys (how many people would drive to Paris?).

Given the palava that is associated with loading and unloading from the shuttle I doubt it would have been slower end to end, especially when you can start the crossing at any time.

And I doubt a crossing would be paralysed by only one vehicle, considering it would almost certainly have more than one lane in each direction.

And it would have enabled a cultural shift - driving through a tunnel or across a bridge is far less of a psychological break than taking a ferry or driving onto a train.

And if a drive-through crossing had driven all the ferries out of business what would happen if it had to be closed because of, say, a vehicle fire? Which would be a far more frequent and dangerous event than in the more controlled surroundings of Eurotunnel. Even fairly detailed checks on each vehicle (=more delay) won't identify for certain any that are at risk of bursting into flames, especially as a fire could result from a RTA or from a terrorist making use of the contents of their fuel tank.

Running through the Tunnel at 186mph instead of 100mph would only save about 3min.

Well at that point it would be more likely that we would have some sort of bridge type crossing instead of a tunnel.
Such as a Great Belt Style combined bridge-tunnel solution, which I believe was one of the proposed options. (Turns out it was 'Euroroute')
But that is not necessarily an issue.

 

[najaB]

Given the palava that is associated with loading and unloading from the shuttle I doubt it would have been slower end to end, especially when you can start the crossing at any time.

You'd have nearly as much since the security and immigration checks would still happen.

And I doubt a crossing would be paralysed by only one vehicle, considering it would almost certainly have more than one lane in each direction.

Likely it would be two lanes, a broken down vehicle halves the capacity - and it would happen way too often.

 

[HSTEd]

You'd have nearly as much since the security and immigration checks would still happen.

Why would you have specific (non customs) security checks?
A relatively short tunnel is far less vulnerable to a terrorist attack than the huge tunnel complex of the current solution.

Likely it would be two lanes, a broken down vehicle halves the capacity - and it would happen way too often.

Euroroute proposed two lanes with a full hard shoulder - which means you would only loose a third of capacity using modern managed motorway techniques.

 

[edwin_m]

Why would you have specific (non customs) security checks?
A relatively short tunnel is far less vulnerable to a terrorist attack than the huge tunnel complex of the current solution.

A vehicle fire, however caused, in a drive-through tunnel is likely to be far more serious than in the Eurotunnel, because of the number of vehicles that will enter the incident area before they can be stopped, and the impossibility of turning them back when yet more are arriving behind them. You probably can't turn an artic in the width of two carriageways and a hard shoulder in any case. It will be necessary to stop everything and get the people out into a safe space in a separate tunnel, then find some way of evacuating them in a reasonable time because you can't just stop people in the other tunnel and tell them to pick up hitch-hikers! People in vehicles will probably be reluctant to leave them until the danger becomes obvious, by which time it may be too late.

By contrast a fire on a shuttle train can be isolated relatively easily, affecting only the one train in the worst case (and less than that if it's a car shuttle assuming the fire containment works). Even if the incident train is crippled, following trains can reverse out so there is only one trainload requiring evacuation, which can be done by transfer to a train in the other tunnel.

 

[HSTEd]

A vehicle fire, however caused, in a drive-through tunnel is likely to be far more serious than in the Eurotunnel, because of the number of vehicles that will enter the incident area before they can be stopped, and the impossibility of turning them back when yet more are arriving behind them. You probably can't turn an artic in the width of two carriageways and a hard shoulder in any case. It will be necessary to stop everything and get the people out into a safe space in a separate tunnel, then find some way of evacuating them in a reasonable time because you can't just stop people in the other tunnel and tell them to pick up hitch-hikers! People in vehicles will probably be reluctant to leave them until the danger becomes obvious, by which time it may be too late.

These risks are however considered soluble in many other road tunnels that operate for years with few or no incidents.
The lessons of the Mont Blanc tunnel fire have been noted in this case.
And the Euroroute solution would also allow vehicles to be monitored during the bridge crossing prior to entering the tunnel that would give a window to use equipment to detect fires on lorries and the like that are moving towards the tunnel entrance, potentially allowing them to be stopped before they enter the tunnel.

The real problem is that people see little difference to loading aboard a ferry to loading aboard a car shuttle, which is why Eurotunnel will never pay for itself.

You could also use managed motorway style lights to stop traffic in an emergency then drop fire containment doors to close off the carriageway, pedestrian access would remain open through a marked door to allow people in the section with the fire to escape.
As such a relatively short and large cross section tunnel would be an immersed tube anyway it could also be quite feasibly fitted with a full scale sprinkler system throughout, as it has no need for a primary water main to achieve that.
So any fire would be out in a minute or so.

 

[TheKnightWho]

On the other hand it would have been more expensive (additional ventilation requirements), would have been slower to cross (speeds would probably be limited to around 50mph), could be paralysed by one broken-down vehicle and wouldn't have enabled any additional through journeys (how many people would drive to Paris?).

How many people drive 300 miles? Quite a lot, actually. It would also enable proper economic integration between Kent and Pas de Calais, which would be a real boon, since it would begin to dispel this idea that Britain is inherently cut off from and different to the continent.

 

[Clip]

How many people drive 300 miles? Quite a lot, actually. It would also enable proper economic integration between Kent and Pas de Calais, which would be a real boon, since it would begin to dispel this idea that Britain is inherently cut off from and different to the continent.

It is and it is.

As lovely as a road tunnel sounds are people happy for all those who work in the port and on the ferries to lose their jobs just so you can see your dream of driving under the sea? mint.