Graeme Wall wrote:
On 19/06/2019 18:02, Basil Jet wrote:
On 19/06/2019 14:03, Graeme Wall wrote:
On 19/06/2019 13:34, Recliner wrote:
On Wed, 19 Jun 2019 12:24:15 +0100, Roland Perry
wrote:

In message , at 12:04:50 on
Wed, 19 Jun 2019, Recliner remarked:

I pointed out that the buried/bridged
motorway will be built on a new alignment, to the west of the current
M25, so building it won't disrupt the existing motorway or flights.
Only the short period of linking the old carriageways and new
diversion will cause any disruption, and that should be short (mainly
a few days or weeks of lane closures, then a few hours of complete
closure while the traffic is switched to the new route).

It's far too close to the intersection with the M4 for the geometry to
work. Not only that, Heathrow's own information shows the M25 route
undiverted (only local roads have new corridors):

https://aec.heathrowconsultation.com...tes/5/2019/06/

P1-11-Local-Roads-Diverted.jpg

Thanks for that. That map clearly confirms the M25 diversion to the
west: it has a more pronounced curve under the runways than the
current route. It's a small enough diversion not to need any changes
to the M4 junction.

I've overlaid a translucent Google Map view on top of the new map, and
you can clearly see the diversion.

https://www.flickr.com/photos/recliner/48091808766/in/dateposted-friend/lightbox/



That confirms it is going to be foul of the current interchange which
is going to be less easy to adapt.

... although no bridges in either junction will have to be rebuilt.


If the new layout is foul of the current junction how is that going to work?


You first connect the completed new carriageway and its M4 slip road to the
old slip road just before it splits into the east and west bound links. For
the next few months, traffic heading for the M4 will be diverted to the new
northbound carriageway, while through traffic will continue to use the
existing carriageway. During this time, the new carriageway will be built
through the old northbound slip road to connect to the ood carriageway.
Again, there will be and closures for a few weeks and an overnight complete
closure as the final connection is made.

Southbound is easier, but, again, connecting traffic from the M4 might
continue to use the old carriageway for a little while after the through
M25 traffic has been diverted to the new carriageway.

In article , tim...
writes
I have never in my life seen construction companies do this
even when the new road is well away from the old route
It costs millions extra to do it that way

Come and look at the A14 rebuild between Girton and Swavesey. It's being
done in a similar way.

--
Clive D.W. Feather

In article , tim...
writes
If you think that they can link a new route into a current motorways by only
diverting traffic for a few weeks then you have never seen how they do this

They're doing it where I live.

IME they narrow the road where the connection is to be made for the full
term of the works. They do this because they need access to the new road
for construction vehicles - how else are they going to build it?

Haul roads. That's what they use here.

They have narrowed the A14, I accept, but that's because they're also
doing stuff along the existing verges.

--
Clive D.W. Feather

In message , at 21:07:58 on Wed, 19 Jun
2019, Clive D.W. Feather remarked:
I have never in my life seen construction companies do this
even when the new road is well away from the old route
It costs millions extra to do it that way

Come and look at the A14 rebuild between Girton and Swavesey. It's being
done in a similar way.

And there's only disruption to the through traffic for two isolated
overnight periods (while they switch some virtual points)?

You have got-to-be-joking.
--
Roland Perry

In message , at 21:07:04 on Wed, 19 Jun
2019, Clive D.W. Feather remarked:
In article , Roland Perry
writes
Presumably all the rerouting of traffic on the A14 project is going
swimmingly, to a similar plan?

All the bits I've seen have been.

For example, the new temporary northwestbound entry slip at Bar Hill was
done that way. There's lots of bits of new carriageway waiting to be
connected (e.g. northwestbound between the services north of Bar Hill
and the Swavesey intersection, though I think that's waiting for the
Lolworth bridge to be completed).

Or, for another example, the diversion of the westbound A14 loop on to
the M11 (or possibly temporarily-not-M11). Or the diversion of the
northwestbound A1307 between Girton and the new Dry Drayton roundabout.

You are obviously familiar with a completely different A14 to the one
where I've endured [Milton to Girton] numerous lane and carriageway
closures, contraflows, and other such disruption, for what's got to be
two years now. Luckily I don't have much reason to travel Girton the
Huntingdon, but I'm sure that's just as chaotic.
--
Roland Perry

Roland Perry wrote:
In message , at 20:09:11 on Wed, 19 Jun
2019, Basil Jet remarked:
I currently do have sight problems but that diagram clearly shows
the slip roads from the new alignment being foul of the existing
layout. I'm hoping to go and see the actual documents in the library
tomorrow so may get a better idea then.

The bridges are all in the centres of the junctions, and the roads in
those area are unchanged, unlike the roads on the southern part of the
M4 junction or the northern part of the T5 junction. (I'm not counting
gantries as bridges.)

Talking of gantries; along with lamp-posts, central reservation
barriers, and all the other street furniture, they'd have to be removed
along the affected stretches to make the "set of points, with road cones
swapping the flow overnight" operation postulated up-thread.

Yes, that's true. There would need to be some overnight closures leading up
to the actual switch. Some items could be removed well in advance, during
other works. Removal of overhead gantries would obviously require overnight
closures, but could be done well in advance. Presumably there won't be more
than one overhead gantry in each of the shirt connection zones.

But quite a lot could be done with just lane closures. For example, the
central reservation won't be affected while the northbound carriageway is
moved across in two stages. Later, when it's time to move the southbound
traffic, much of the structure removal and connection work will be done
during closures of the fast lane. The final switchover will require an
overnight closure while the 'points are switched'.

"Recliner" wrote in message
...
tim... wrote:


"Recliner" wrote in message
...
On Wed, 19 Jun 2019 12:43:48 +0100, "Clive D.W. Feather"
wrote:

In article , Roland Perry
writes
The only disruption will come at the end, when the traffic is
diverted
to
the new route. My guess is that the northbound traffic will be moved
first,
with a few weeks of lane 1 closures required while they connect the
new
to
the old carriageways, then an overnight closure for the final switch
to
be
made. The same procedure would then be followed a few months later to
divert the southbound carriageway to the new alignment.

The amount of work you would be expecting them to do "overnight"
beggars
belief.

I disagree.

Build the two new carriageways. At each end, cut them off very close to
the edge of northbound lane 1 (there's no hard shoulder, right? if
there
is, adjust description accordingly).

Cone off northbound lane 1. Spend a week or two filling in the narrow
gap between the old and new northbounds at each end.

Not sure that you even need a closure to switch over. Simply move all
the cones.

Repeat for the southbound (though this time you're closing lane 4).


Yes, that's what I'm expecting.

I have never in my life seen construction companies do this

even when the new road is well away from the old route

It costs millions extra to do it that way

Why would it cost any extra?

because you have to build a "throw away" access road to the new build road.

The alternative of accessing via the current road is "free" but causes some
of that road to need closing

"Recliner" wrote in message
...
tim... wrote:


"Recliner" wrote in message
...
On Wed, 19 Jun 2019 10:57:29 +0100, "tim..."
wrote:



"Recliner" wrote in message
...
tim... wrote:


"Recliner" wrote in message
...
tim... wrote:


"Recliner" wrote in message
...
https://www.bbc.co.uk/news/business-48668001


well I don't know about the rest,

but I for one think that the idea that people who have little or no
business
at the airport are going to have to suffer 5 years of disruption
whilst
they
rebuild the M25 to create this Hub airport entirely unreasonable

Why do you think M25 users will suffer five years of disruption?
It's
more
likely to be a few night time closures or lane restrictions.

they are going to put the whole road in a tunnel (presumably from the
way
it's described not by building a raft on top of it)

how can that not cause major disruption?


You've obviously not looked at the map,

what is "The Map" - I guess there is one, but no I didn't get to see it
(You
can blame that on my out of date browser if the original article
included
a
link)

or read this thread.

as one of the first to reply, that would have been difficult

If you now read the thread, I pointed out that the buried/bridged
motorway will be built on a new alignment, to the west of the current
M25, so building it won't disrupt the existing motorway or flights.

The plans that I can see show the new road so close that the idea that it
wont disrupt the current M25 is fiction.

Only the short period of linking the old carriageways and new
diversion will cause any disruption, and that should be short (mainly
a few days or weeks of lane closures, then a few hours of complete
closure while the traffic is switched to the new route).

If you think that they can link a new route into a current motorways by
only
diverting traffic for a few weeks then you have never seen how they do
this

IME they narrow the road where the connection is to be made for the full
term of the works. They do this because they need access to the new road
for construction vehicles - how else are they going to build it?

They won't need access to the existing M25 to build the new structures to
the west — why would they?

because they don't helicopter all the construction stuff in, do they

tim

"Clive D.W. Feather" wrote in message
...
In article , tim...
writes
I have never in my life seen construction companies do this
even when the new road is well away from the old route
It costs millions extra to do it that way

Come and look at the A14 rebuild between Girton and Swavesey. It's being
done in a similar way.

fortunately, I have no need to travel that way frequently anymore

but when i did, the plan was that the exit that I used every day was to be
closed in order to facilitate the rebuilt

And on the one occasion that I did travel that way, there was certainly
cones along the whole of the road closing off lanes and restricted speed
limits

tim

tim... wrote:


"Recliner" wrote in message
...
tim... wrote:


"Recliner" wrote in message
...
On Wed, 19 Jun 2019 12:43:48 +0100, "Clive D.W. Feather"
wrote:

In article , Roland Perry
writes
The only disruption will come at the end, when the traffic is
diverted
to
the new route. My guess is that the northbound traffic will be moved
first,
with a few weeks of lane 1 closures required while they connect the
new
to
the old carriageways, then an overnight closure for the final switch
to
be
made. The same procedure would then be followed a few months later to
divert the southbound carriageway to the new alignment.

The amount of work you would be expecting them to do "overnight"
beggars
belief.

I disagree.

Build the two new carriageways. At each end, cut them off very close to
the edge of northbound lane 1 (there's no hard shoulder, right? if
there
is, adjust description accordingly).

Cone off northbound lane 1. Spend a week or two filling in the narrow
gap between the old and new northbounds at each end.

Not sure that you even need a closure to switch over. Simply move all
the cones.

Repeat for the southbound (though this time you're closing lane 4).


Yes, that's what I'm expecting.

I have never in my life seen construction companies do this

even when the new road is well away from the old route

It costs millions extra to do it that way

Why would it cost any extra?

because you have to build a "throw away" access road to the new build road.

I take it you've never looked at a map of the area, or even Google Maps?


The alternative of accessing via the current road is "free" but causes some
of that road to need closing

There are plenty of other existing roads, including the A4, they can use
for access to the work sites.