M25 Heathrow Tunnel

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mapalex
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M25 Heathrow Tunnel

Post by mapalex » Tue Dec 01, 2015 12:59

It looks like Heathrow runway three will get the go ahead from the Government soon.

What I would like to ask is, how will the tunnel under the new runway, carrying the M25, be constructed, without closing the carriageway?

It looks like it may affect the future layout of the M4 junction as well.

Obviously a temporary carriageway might be an option, but given the width of the motorway at this point, this would appear unworkable to me.

Reading
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Re: M25 Heathrow Tunnel

Post by Reading » Tue Dec 01, 2015 13:33

wouldnt they do the same as building a new bridge it is the same thing but bigger (assuming the bed of carriageway is staying at same level) - all the embankment / buttress works first with carriage way closures, same for pillars in central res, then beams across top during night closures.

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si404
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Re: M25 Heathrow Tunnel

Post by si404 » Tue Dec 01, 2015 14:03

mapalex wrote:It looks like Heathrow runway three will get the go ahead from the Government soon.
It doesn't.
What I would like to ask is, how will the tunnel under the new runway, carrying the M25, be constructed, without closing the carriageway?
Build the new route through the tunnel parallel, then close the existing route.
It looks like it may affect the future layout of the M4 junction as well.
It won't - they changed their plan. Of course, it's quite clear that the junction would need a rebuild anyway due to the runway proposals, but Heathrow have deep pockets and very short arms and will try their best to minimise their spending on infrastructure that isn't theirs (eg their getting out of paying S106 payments for Crossrail) and so the roads that are under the new runway is all they are going to commit to paying for.
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Re: M25 Heathrow Tunnel

Post by ScottB5411 » Tue Dec 01, 2015 16:32

Only in the UK is there so much dithering with projects. Most other countrys would have had it built eons ago instead of wasting millions holding pointless repetitive meetings about the same thing. No wonder there's no money for anything, it costs too much for all the fancy lunches at all the meeting they have to hold for 10 years before a shovel is picked up.
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Re: M25 Heathrow Tunnel

Post by Glom » Tue Dec 01, 2015 21:10

The latest proposal from HAL is immense.

Because the 3rd runway is now more closely space to the existing runway, junction 15 is now left as is.

The tunnelled section is just a bit to the West of the existing alignment so it would be built offline and the traffic shifted over when it's ready.

There are 4 tunnels, for two mainline carriageways (D4M I think) and two on the outside from C/D lanes (D3M) for the M4, which actually connect to the mainline at junction 14.

It's like the road porn that was posted a couple of months back about the Denham spur.

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Re: M25 Heathrow Tunnel

Post by WHBM » Tue Dec 01, 2015 21:20

I too have seen that the government is about to announce that after great deliberations they go along with the Davies Commission's own deliberations and favour a Heathrow third runway.

What I can't believe is that the whole thing will now have to go for PLANNING PERMISSION :roll: However many times do we need to ask the same question. You just couldn't make it up.
Because the 3rd runway is now more closely space to the existing runway
I'll be surprised. There is a design standard that stipulates independent parallel runways must have at least 1035m between their centrelines - which is how I understood it was originally designed.

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Big L
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Re: M25 Heathrow Tunnel

Post by Big L » Tue Dec 01, 2015 21:31

1035m?
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M4 Cardiff
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Re: M25 Heathrow Tunnel

Post by M4 Cardiff » Tue Dec 01, 2015 22:18

to ensure 1000m lateral separation between aircraft, assuming 35m half wingspan possibly
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Re: M25 Heathrow Tunnel

Post by hoagy_ytfc » Tue Dec 01, 2015 23:44

WHBM wrote:
What I can't believe is that the whole thing will now have to go for PLANNING PERMISSION :roll: However many times do we need to ask the same question. You just couldn't make it up.
You think due legal process should be skipped?

You probably ought to brace yourself for a public inquiry too.

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Re: M25 Heathrow Tunnel

Post by si404 » Wed Dec 02, 2015 01:42

hoagy_ytfc wrote:You probably ought to brace yourself for a public inquiry too.
That will cost the taxpayer more than they would spend total on Gatwick, and, by the time its done, Gatwick's runway could have been open.

That they are making a decision on Heathrow this week, with Heathrow not budging on things like not paying the DfT for transport improvements beyond rebuilt public roads that need to be diverted for the new runway (and WRAtH, which they will run like Heathrow Express) despite being told that they have to to get approval from the HoC Committee that is analysing the Davis Report, then the odds are much more likely to be negative.
Glom wrote:There are 4 tunnels, for two mainline carriageways (D4M I think) and two on the outside from C/D lanes (D3M) for the M4, which actually connect to the mainline at junction 14.
And given that all Heathrow traffic will now go via J14 (OK, some might still go via the M4 spur), and the airport is 50% larger, how is one extra lane going to cut the mustard?
It's like the road porn that was posted a couple of months back about the Denham spur.
It's not anywhere near as epic, and it ends at J14 and J15 on the M25.
WHBM wrote:However many times do we need to ask the same question.
Until we stop asking the wrong question? That is the one that expects Heathrow to be the answer.

Davis had to pull out the 'right' answer out of the hole between his lower cheeks and it felt, for those following the noises he was making while writing it (competition, minimise noise disruption, etc), to be fairly surprising. A cursory glance at the report would explain how the 'right' answer was obtained: eg Heathrow would increase those affected by noise by 40% (or whatever), whereas Gatwick would affect 400% (or whatever) the amount currently so - a fact that is true, but ignores that 40% more for Heathrow is 10 times 400% more for Gatwick, but absolute figures nor direct comparisons to be found in the final report.
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Re: M25 Heathrow Tunnel

Post by Big L » Wed Dec 02, 2015 08:09

Big L wrote:1035m?
According to google,
In summary, "For simultaneous landings and takeoffs using VFR, the minimum separation between centerlines of parallel runways is 700 feet (213 m)." For simultaneous IFR operations, "Dual simultaneous precision instrument approaches are normally approved on parallel runway centerline separation of 4,300 feet (1311 m).26 Feb 2015
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Re: M25 Heathrow Tunnel

Post by Vierwielen » Wed Dec 02, 2015 08:16

I have often wondered how feasible it would be to install a few railway links so that it would be possible to run a Cambridge-Stansted-Heathrow-Southampton Airport-Southamton service and a Manchester-Manchester Airport-Birmingham-Birmingham Airport-Heathrow-Gatwick-Brighton Service?

This might help distribute the traffic and remove the need for the 3rd runway at Heathrow.

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Re: M25 Heathrow Tunnel

Post by Comstock » Wed Dec 02, 2015 08:55

This one is really simple. Fly less. No runway needed. Job done.

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roadtester
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Re: M25 Heathrow Tunnel

Post by roadtester » Wed Dec 02, 2015 09:04

Comstock wrote:This one is really simple. Fly less. No runway needed. Job done.
It's just not realistic.

Also, what people usually mean by "fly less" is "everybody else fly less"...

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Re: M25 Heathrow Tunnel

Post by Comstock » Wed Dec 02, 2015 09:11

roadtester wrote:
Comstock wrote:This one is really simple. Fly less. No runway needed. Job done.
It's just not realistic.

Also, what people usually mean by "fly less" is "everybody else fly less"...
Not in my case. I'm 41 and have never flown. My parents are both seventy and have flown once each, both short haul flights the 1970s

Unlike driving, flying is almost always a choice.

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Re: M25 Heathrow Tunnel

Post by Vierwielen » Wed Dec 02, 2015 09:28

Comstock wrote:
roadtester wrote:
Comstock wrote:This one is really simple. Fly less. No runway needed. Job done.
It's just not realistic.

Also, what people usually mean by "fly less" is "everybody else fly less"...
Not in my case. I'm 41 and have never flown. My parents are both seventy and have flown once each, both short haul flights the 1970s

Unlike driving, flying is almost always a choice.
On the other hand, when work dried up for me in the UK, I spent three years contracting in the Netherlands, Germany and Italy. My routine was to commute fortnightly by air. Now had there been decent rail services between the Netherlands and London and between Frankfurt and London, I would probably have used rail.

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Re: M25 Heathrow Tunnel

Post by roadtester » Wed Dec 02, 2015 09:33

Comstock wrote: Not in my case. I'm 41 and have never flown. My parents are both seventy and have flown once each, both short haul flights the 1970s

Unlike driving, flying is almost always a choice.
That's a bit of a narrow argument.

Even if you never step on a plane yourself, your standard of living depends vitally on systems of commerce and government to which the use of aviation is central.

If anyone wants to go on vital business to the US or Australia, or even just visit their granny there, there is no real choice but to fly. Most UK journeys undertaken by car probably have alternatives.

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Re: M25 Heathrow Tunnel

Post by roadtester » Wed Dec 02, 2015 09:37

Vierwielen wrote: On the other hand, when work dried up for me in the UK, I spent three years contracting in the Netherlands, Germany and Italy. My routine was to commute fortnightly by air. Now had there been decent rail services between the Netherlands and London and between Frankfurt and London, I would probably have used rail.
That's due to scandalous under-exploitation of Eurotunnel for longer through journeys outside the main London, Brussels and Paris set-up - partly, I suspect, because of the UK's insistence on aviation-style security screening and static passport controls.

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Re: M25 Heathrow Tunnel

Post by Comstock » Wed Dec 02, 2015 09:48

roadtester wrote: Even if you never step on a plane yourself, your standard of living depends vitally on systems of commerce and government to which the use of aviation is central.
As I've said on here before, I'm far from convinced standards of living for the ordinary Joe today are significantly higher than they were 50 years ago, when almost no one flew.

Anyway, getting off topic (and I am to blame)- I might start a thread on Unleashed about comparitive standards of living at some stage :D

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Re: M25 Heathrow Tunnel

Post by Fenlander » Wed Dec 02, 2015 10:14

Comstock wrote:Anyway, getting off topic (and I am to blame)- I might start a thread on Unleashed about comparitive standards of living at some stage :D
Go for it, instead of commenting on the thread we could write our replies on parchment and have a messenger deliver them. :wink:

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