• Our booking engine at tickets.railforums.co.uk (powered by TrainSplit) helps support the running of the forum with every ticket purchase! Find out more and ask any questions/give us feedback in this thread!

Why can HS2 go faster?

Status
Not open for further replies.
Sponsor Post - registered members do not see these adverts; click here to register, or click here to log in
R

RailUK Forums

edwin_m

Veteran Member
Joined
21 Apr 2013
Messages
24,793
Location
Nottingham
That is how physics works - the laws of same are immutable - regardless of DfT notions. I still struggle with the 18 trains p.hour to Brum - why? To have that capacity is fine but, when passenger figures have started to drift off in the SE..... Could there really be a max. demand of some 18k people p.hour to Brum and back?
18 trains per hour is the eventual total between London and Birmingham, Manchester, Liverpool, Leeds, Newcastle, Glasgow, Edinburgh and possibly other places I've forgotten about.
 

HSTEd

Veteran Member
Joined
14 Jul 2011
Messages
16,630
The simple kinetic energy equation: K.E. = 1/2×m×v^2 shows that at 320km/h, assuming constant m, the energy requirement is approximately 14% higher than at 300km/h. Considering that wind resistance is also a square function of the speed (velocity), this too is approximately 14% higher at 320km/h.

So whilst twice the energy is probably an overstatement, it would not be unreasonable to think that a 50% or greater increase in input energy would be required to attain 320km/h.

Although it will take a whilst to dig out the report, I believe the best estimate I've seen is that a TGV Duplex at 320km/h uses less energy per passenger km than a Cl390 at 200km/h, because the Duplex is far lighter.
 

Altnabreac

Established Member
Joined
20 Apr 2013
Messages
2,414
Location
Salt & Vinegar
18 trains per hour is the eventual total between London and Birmingham, Manchester, Liverpool, Leeds, Newcastle, Glasgow, Edinburgh and possibly other places I've forgotten about.

Carstairs, Darlington, York, Sheffield, Chesterfield, East Midlands Interchange, Preston, Wigan North Western, Warrington Bank Quay, Runcorn, Manchester Airport, Crewe, Stafford, Birmingham Interchange on the latest published business case.

Motherwell, Lockerbie, Carlisle, Penrith, Oxenholme, Lancaster and Durham have Birmingham services in the latest business case but no London calls.

Probably London services from Carlisle (replacing Carstairs), Stoke , Macclesfield will be added in the next iteration of the business case.

Eventually I'd not be surprised to see Stockport, Lancaster, Blackpool North, Durham and Northallerton added to the list of places receiving HS2 London bound calls in Phase 2B once the detailed service specification is developed.
 

The Planner

Veteran Member
Joined
15 Apr 2008
Messages
15,836
Stockport won't, the only reason Macclesfield is on there is that its assumed you cannot get across Cheadle Hulme. Would be very surprised to see Blackpool too.
 

HSTEd

Veteran Member
Joined
14 Jul 2011
Messages
16,630
There is no reason to put a high speed train into stockport, the bulk of Stockport traffic will be eaten up by the Airport I would exepct.
 

Altnabreac

Established Member
Joined
20 Apr 2013
Messages
2,414
Location
Salt & Vinegar
Stockport won't, the only reason Macclesfield is on there is that its assumed you cannot get across Cheadle Hulme. Would be very surprised to see Blackpool too.

Have you noticed the number of marginal constitiencies around Fylde, Wyre and Fleetwood? Extending the Preston terminators 2-4 times per day would be a very easy political sop at a minimal cost, hence why I think it will happen eventually, rather than on pure Transport grounds.
 

Altnabreac

Established Member
Joined
20 Apr 2013
Messages
2,414
Location
Salt & Vinegar
There is no reason to put a high speed train into stockport, the bulk of Stockport traffic will be eaten up by the Airport I would exepct.

Again it's a case of an easy extension of a classic set from Macclesfield for minimal cost gaining maximum political benefit. I don't think it will be in the business case but it's the sort of thing that could easily be added once the initial service is up and running.
 

HSTEd

Veteran Member
Joined
14 Jul 2011
Messages
16,630
Again it's a case of an easy extension of a classic set from Macclesfield for minimal cost gaining maximum political benefit. I don't think it will be in the business case but it's the sort of thing that could easily be added once the initial service is up and running.

Problem is Stockport Terminators might not go down well in terms of platform usage, and running through to Picadilly will likely be scotched - local services are already being lined up for the paths through Stockport after all.
 

Altnabreac

Established Member
Joined
20 Apr 2013
Messages
2,414
Location
Salt & Vinegar
Problem is Stockport Terminators might not go down well in terms of platform usage, and running through to Picadilly will likely be scotched - local services are already being lined up for the paths through Stockport after all.

Suspect if it came to pass it would probably run through to Bolton / Preston alternating with the proposed WCML Glasgow - Euston via Piccadilly Platform 13/14 service proposed in the HS2 business case.

It's not a service that is going to boost a business case though so I wouldn't expect to see it appear until post Phase 2B opening. Much more a political service added on later.
 

MarkyT

Established Member
Joined
20 May 2012
Messages
6,232
Location
Torbay
Again it's a case of an easy extension of a classic set from Macclesfield for minimal cost gaining maximum political benefit. I don't think it will be in the business case but it's the sort of thing that could easily be added once the initial service is up and running.

Probably wasteful largely empty mileage and hours for an expensive asset that could be deployed more usefully elsewhere. The hardship of losing direct London service from Stockport for those living in the immediate area and not having sole access to a car they can drive and leave all day at Manchester airport could be ameliorated somewhat by a fast frequent eastern orbital Metrolink route (tram-train) between the HS2 station at Manchester airport and Stockport, perhaps continuing on to Ashton-under-Lyne via Reddish and Denton, then Oldham and Rochdale. That would be a much better result for many more people than running a token HS2 service extension, and give Stockport residents access, via one change, to a much faster HS2 rail service to London. I'd also suggest a fast free shuttle lift connection between Stockport's rail and bus station levels, perhaps using some kind of rubber tyred autonomous pod technology rather than a traditional funicular or sloped elevator, but largely on dedicated lane as far as possible to ensure speed and priority while also allowing space sharing at crossings with pedestrians where expedient. A single lane 'virtual funicular' on rubber tyres with two reversible midi bus sized cars and a passing loop in the middle, or a larger number of smaller cars cycling on demand more frequently when required on a continuous narrow one way loop like Ultra at Heathrow.
 

HSTEd

Veteran Member
Joined
14 Jul 2011
Messages
16,630
I'd also suggest a fast free shuttle lift connection between Stockport's rail and bus station levels, perhaps using some kind of rubber tyred autonomous pod technology rather than a traditional funicular or sloped elevator, but largely on dedicated lane as far as possible to ensure speed and priority while also allowing space sharing at crossings with pedestrians where expedient. A single lane 'virtual funicular' on rubber tyres with two reversible midi bus sized cars and a passing loop in the middle, or a larger number of smaller cars cycling on demand more frequently when required on a continuous narrow one way loop like Ultra at Heathrow.

Honestly an off-the-shelf MDG Gondola or something would perfectly fit the requirement.
Or even just a set of escalators.
Its not very far but it is rather steep.
 

corsaVXR

Member
Joined
22 Oct 2007
Messages
90
Can you please substantiate your assertion that I've bolded and italicised above? A valid hyperlink to your source could make the statement credible.

Power consumption is proportional to velocity cubed.

The main resistance force on the train will be aerodynamic drag. There will be a bit of rolling resistance from the interaction between the wheels and the track, and the internal running gear (bearings, transmissions etc), which while not totally negligible, it will (probably) increase linearly with speed and be low compared to the aerodynamic drag.

Aerodynamic drag is equal to: 0.5*[Air Density]*[Cross sectional Area of the train]*[Drag Coefficient]*[Velocity ^2].

Power consumption is equal to [Force]*[Velocity]

At a steady speed, all forces are equal, so the running force will equal to the resistance force.

Therefore, for a given Speed, the Power Consumption will be equal to 0.5*[Air Density]*[Cross sectional Area of the train]*[Drag Coefficient]*[Velocity ^3]

Assuming the air density and the shape of the train doesn't change, this can be used to compare power consumption at different speeds.

Therefore based on aerodynamic drag alone, at 300kph, the power consumption will be ~37% higher than at 270kph. At 320kph, the power consumption is ~66% higher than at 270kph, and ~21% higher than at 300kph.
 

HSTEd

Veteran Member
Joined
14 Jul 2011
Messages
16,630
Therefore based on aerodynamic drag alone, at 300kph, the power consumption will be ~37% higher than at 270kph. At 320kph, the power consumption is ~66% higher than at 270kph, and ~21% higher than at 300kph.

Power consumption is however irrelevant.
Energy consumption is.

Energy consumed is proportional to the square, not the cube, because by doubling the velocity I half the time I must sustain the force against air resistance, since i will reach the destination in half the time.
 

backontrack

Established Member
Joined
2 Feb 2014
Messages
6,383
Location
The UK
Carstairs, Darlington, York, Sheffield, Chesterfield, East Midlands Interchange, Preston, Wigan North Western, Warrington Bank Quay, Runcorn, Manchester Airport, Crewe, Stafford, Birmingham Interchange on the latest published business case.

Motherwell, Lockerbie, Carlisle, Penrith, Oxenholme, Lancaster and Durham have Birmingham services in the latest business case but no London calls.

Probably London services from Carlisle (replacing Carstairs), Stoke , Macclesfield will be added in the next iteration of the business case.

Eventually I'd not be surprised to see Stockport, Lancaster, Blackpool North, Durham and Northallerton added to the list of places receiving HS2 London bound calls in Phase 2B once the detailed service specification is developed.
HS2 should definitely have London calls at Carlisle, without a doubt.
 

AM9

Veteran Member
Joined
13 May 2014
Messages
14,191
Location
St Albans
Power consumption is however irrelevant.
Energy consumption is.

Energy consumed is proportional to the square, not the cube, because by doubling the velocity I half the time I must sustain the force against air resistance, since i will reach the destination in half the time.

That is only true for the energy required to counter the air resistance:
The energy required to counter the rolling resistance is probably proportional to speed
The energy required to counter the mass of the train is only required for acceleration and climbing gradients. Most of that is recoverable through regenerative braking and coasting down gradients respectively
The energy required for 'hotel' requirements is proportional to travelling time (so it is inversely proportionate to journey times)​
So the only energy requirement that is greater because of the higher speed is down to air resistance for which the most streamlined design practicable will be delivered.
 

Ianno87

Veteran Member
Joined
3 May 2015
Messages
15,215
Only if the time taken by adding a call doesn't lengthen the journey time by more than the time taken to connect at Preston.

Weighted by number of passengers joining at Carlisle vs number already on from Glasgow/Edinburgh who'd be slowed down.

More you get off the Scotland journey time, the more you abstract from air and the greater the environmental benefits. How that balances with the benefits to Carlisle and its wide hinterland of prospective passengers who'd benefit from a stop (vs a 'good' connection at Preston, or even Curzon Street), don't know.
 

Altnabreac

Established Member
Joined
20 Apr 2013
Messages
2,414
Location
Salt & Vinegar
Only if the time taken by adding a call doesn't lengthen the journey time by more than the time taken to connect at Preston.

Splitting / Joining at Preston is not on the agenda. There simply isn't enough capacity on the WCML over Shap to allow it.

There are broadly three options.
Carstairs
Carlisle
No splitting

Within that there are some sub options like having a split at Carstairs but without a passenger call there and the no splitting has East and West coast options for serving Edinburgh.

I think Carstairs is the least likely to happen with no split vs Carlisle being finely balanced.
 

najaB

Veteran Member
Joined
28 Aug 2011
Messages
30,691
Location
Scotland
Splitting / Joining at Preston is not on the agenda. There simply isn't enough capacity on the WCML over Shap to allow it.
I meant passengers making a connection from a local/slow train to HS2 at Preston, rather than splitting/joining. :)
 

Altnabreac

Established Member
Joined
20 Apr 2013
Messages
2,414
Location
Salt & Vinegar
I meant passengers making a connection from a local/slow train to HS2 at Preston, rather than splitting/joining. :)

Ah right.

The most likely justification for calls at Carlisle will be to allow splitting joining rather than on passenger demand from Carlisle itself. So journey time via Preston is only going to be a small part of whether Carlisle gets London HS2 calls
 

NotATrainspott

Established Member
Joined
2 Feb 2013
Messages
3,223
Splitting at Carstairs has also got the disadvantage of needing a complex shunt/reversal, rather than just a straightforward split in the platforms. If you're trying to shave off as many minutes as possible from Scotland times it might make more sense to take the split/join hit at Carlisle (which will have a fairly low non-stop speed unless an expensive bypass is built). By far the cheapest and simplest intervention to speed up Edinburgh journey times by several minutes would be to rebuild the original railway route at Carstairs and bypass the horrible reverse-cant curve.
 

Wychwood93

Member
Joined
25 Jan 2018
Messages
634
Location
Burton. Dorset.
I still struggle with the 18 trains p.hour to Brum - why? (wychood93)
It's 18 trains per hour leaving London, about three or four to Birmingham. The rest go on to northern England via the two branches.

https://assets.publishing.service.g...on_of_the_service_patterns__January_2013_.pdf
A somewhat belated reply, sorry - the link to not viewed links just popped up. I note the link above still shows services from Heathrow (when?) - ignoring that minor bit the proposal looks sort of possible. I still have concerns about demand though. Not only demand but, of more interest, pricing. Also, as with AVE, TGV, do/will seats have to be reserved in advance? The loss of turn up and go as a result of the high speed - the HS1 395s are nippy at up to 140, but perfectly open and not exactly 'high speed'. Having said that, I was on a double-set TGV from Avignon Centre to Lille a few years ago - rear set oou already (where my seat was meant to be) - grabbed a seat in the front set until Lyon PD and then it was full and standing from then on. Me and about ten others in a vestibule at 300 kph.
 

Ianno87

Veteran Member
Joined
3 May 2015
Messages
15,215
A somewhat belated reply, sorry - the link to not viewed links just popped up. I note the link above still shows services from Heathrow (when?) - ignoring that minor bit the proposal looks sort of possible. I still have concerns about demand though. Not only demand but, of more interest, pricing. Also, as with AVE, TGV, do/will seats have to be reserved in advance? The loss of turn up and go as a result of the high speed - the HS1 395s are nippy at up to 140, but perfectly open and not exactly 'high speed'. Having said that, I was on a double-set TGV from Avignon Centre to Lille a few years ago - rear set oou already (where my seat was meant to be) - grabbed a seat in the front set until Lyon PD and then it was full and standing from then on. Me and about ten others in a vestibule at 300 kph.

With TGV, as I understand it you have:
-Fixed fares, equivalent to Advances (so no different)
-Flexible fares, which require a seat reservation but is fully changeable using machines at the station.

With HS2, I can envisage (this being 8 years from now) flexible fares working whereby as you emerge from the Tube/Crossrail 2 at Euston, you get your smartphone app out and select your seat there and then, wandering across the concourse and away you go...
 
Joined
18 Oct 2017
Messages
214
I cannot cite a reference, but I recall HS2 saying the intent is that all passengers will be in a "booked in advance" seat so no-one should be standing anywhere. "In Advance" could be as late as a few minutes before departure, (via screens, phone apps, etc.) but essentially you won't be sold a ticket unless there's a seat to sit in. Essentially, it's an "airline" style model instead of the "tube/rail" model we are used to in the UK.
 

NSEFAN

Established Member
Joined
17 Jun 2007
Messages
3,504
Location
Southampton
I cannot cite a reference, but I recall HS2 saying the intent is that all passengers will be in a "booked in advance" seat so no-one should be standing anywhere. "In Advance" could be as late as a few minutes before departure, (via screens, phone apps, etc.) but essentially you won't be sold a ticket unless there's a seat to sit in. Essentially, it's an "airline" style model instead of the "tube/rail" model we are used to in the UK.
That's going to be interesting once the services run onto the mainlines, where people currently enjoy turn-up and go frequencies. I can't imagine that the railway would be happy with the reduced capacity by not allowing people to stand.
 

The Planner

Veteran Member
Joined
15 Apr 2008
Messages
15,836
Splitting / Joining at Preston is not on the agenda. There simply isn't enough capacity on the WCML over Shap to allow it.

There are broadly three options.
Carstairs
Carlisle
No splitting

Within that there are some sub options like having a split at Carstairs but without a passenger call there and the no splitting has East and West coast options for serving Edinburgh.

I think Carstairs is the least likely to happen with no split vs Carlisle being finely balanced.
None of that is decided, Preston isn't binned and there is no timetable yet that says there is not enough capacity over Shap either.
 
Status
Not open for further replies.

Top