270 degrees

[flypie]

If building a new junction would a 270 turn be acceptable it was composed of section of track that where used for other routes through the junction? and allowed the number of points on the high speed section to be reduced by 1?

I'm just considering how a Liverpool to HS2 junction might work with a through route to Manchester which doesn't use the main spine. The issue is the junction from Liverpool going North, which I suspect would be rather under used as might the Manchester North Junction, which is in the current HS2 plans.

I have attached an image which shows a line extending from the old Warrington Altrincham line, past HS2, lining directly to the Manchester spur, with a short chord links the line to the Manchester south curve, providing a Liverpool London ROute, these are in purple. The orange line carries on this curve on and eventually joins the main trunk heading north. If the Orange line was in place then the currently proposed Manchester north curve would be redundant.
I've tried to keep the cures to a 5 km radius, which would allow high speed running, though this may be ambitious.

 

[snowball]

None of the curves in that diagram is what I'd call a 270 degree curve.

There are 270 degree curves in some road junctions - for example two of them in the M6/M62 junction.

 

[flypie]

None of the curves in that diagram is what I'd call a 270 degree curve.

There are 270 degree curves in some road junctions - for example two of them in the M6/M62 junction.

There is one on the A14/M11 and M6/A500 at Cambridge they just don't have the luxurious 5km radii.

Show up better in this image if you image coming from Liverpool in the West and wanting to head north.

 

[snowball]

Sorry, I failed to realise that the purple and orange (purple and yellow in the latest pic) were meant to be usable as part of one troute.

 

[flypie]

Sorry, I failed to realise that the purple and orange (purple and yellow in the latest pic) were meant to be usable as part of one troute.

The fisrt picture was a bit naff. I think I have explained it better here. http://peterirate.blogspot.com/2016/03/liverpool-hs2hs3-junction.html

 

[Altnabreac]

The fisrt picture was a bit naff. I think I have explained it better here. http://peterirate.blogspot.com/2016/03/liverpool-hs2hs3-junction.html

If I understand it the whole problem you are trying to solve is Northern Powerhouse Rail sharing the north south spine with HS2 trains heading north of Wigan.

Given at present the proposed HS2 service here is around 4tph this seems a bit excessive.

Even as a thought experiment the maximum HS2 service I can imagine here is 10tph this doesn't seem necessary.
Max possible:
2tph Edinburgh - Euston
2tph Glasgow - Euston
2tph Scotland - Birmingham
2tph Scotland - Manchester
2tph Preston - Euston

 

[flypie]

If I understand it the whole problem you are trying to solve is Northern Powerhouse Rail sharing the north south spine with HS2 trains heading north of Wigan.

Given at present the proposed HS2 service here is around 4tph this seems a bit excessive.

Even as a thought experiment the maximum HS2 service I can imagine here is 10tph this doesn't seem necessary.
Max possible:
2tph Edinburgh - Euston
2tph Glasgow - Euston
2tph Scotland - Birmingham
2tph Scotland - Manchester
2tph Preston - Euston

That is the main part of the problem. I prefer not to build bottle necks in, it is easier and cheaper to solve them before they arise. The problem would be with tight turns and sharing, this would increase the blockage as the trains would be slowing on the mainline, which would be against some of HS2 policies. A simple bit of quading would solve the problem.

If the flat crossing at Newark never been built. I think all of the junctions on HS2 are either flying or burrowing as a bit of future proofing.

 

[najaB]

That is the main part of the problem. I prefer not to build bottle necks in, it is easier and cheaper to solve them before they arise.

The question that needs answering is how many of today's pounds does it make sense to spend to avoid tomorrow's operational problems?

The answer depends on three things: how many of today's pounds are we spending, how far out is 'tomorrow' and how much of a problem are we talking about?

For example, let's say a bridge on the Highland Mainline needs replacing. Do we build it as a twin track bridge because there's a high probability that the line will be doubled there in the next ten years? Yes, of course.

Do we build it as quad track because there's a slight chance that the line will be quadrupled in 50 years? Probably not.

I think the problem you're trying to solve is closer to the latter example than the former.

 

[flypie]

The question that needs answering is how many of today's pounds does it make sense to spend to avoid tomorrow's operational problems?

The answer depends on three things: how many of today's pounds are we spending, how far out is 'tomorrow' and how much of a problem are we talking about?

For example, let's say a bridge on the Highland Mainline needs replacing. Do we build it as a twin track bridge because there's a high probability that the line will be doubled there in the next ten years? Yes, of course.

Do we build it as quad track because there's a slight chance that the line will be quadrupled in 50 years? Probably not.

I think the problem you're trying to solve is closer to the latter example than the former.

Maybe for Opt 1 and 2 but for Opt 3 I would say that 10k of Quad would be a reasonable insurance and would add to the robustness of what would be one of the more complex junctions on the line.