Where should HS3 go and why?

[po8crg]

It is worth noting that a High Speed line parallel to the SWML could quite easily serve the South West as well.....

A line to Southampton could quite easily have a Salisbury-Yeovil-Exeter spur, its less than a hundred miles, which means a train can cover it in half an hour or less.

My fantasy HS network beyond HS2 has a line going London-Southampton-Bristol-Exeter. Bit of a zig-zag but at HS speeds it gets there quick enough, and it interconnects far more places than direct London-Exeter or London-Bristol lines.

Also, Southampton (and the South Hants conurbation generally) has terrible connections by both rail and road going NW to Bristol. You can't cover the 75 miles from Southampton to Bristol in less than 100 minutes, either by road (A36) or rail. Any decent link between those two regions would very quickly dominate the route, and should generate a lot of new journeys.

 

[59CosG95]

It is worth noting that a High Speed line parallel to the SWML could quite easily serve the South West as well.....

A line to Southampton could quite easily have a Salisbury-Yeovil-Exeter spur, its less than a hundred miles, which means a train can cover it in half an hour or less.

Parallel to the SWML? Good luck trying to persuade the Surrey and Hampshire NIMBYs to budge over-and trying to get it through all the commuter towns...and the MOD land nr. Pirbright Junction. That said, the WoEML parallel would certainly help regenerate South Wilts rail-but a great deal of work will be needed to hide the line nr Tisbury (my 3rd local station), as I know quite a few people who wouldn't like a 200mph line go past every 5 mins-the diesels rattling by every hour is bad enough!!

 

[TheGrew]

Parallel to the SWML? Good luck trying to persuade the Surrey and Hampshire NIMBYs to budge over-and trying to get it through all the commuter towns...and the MOD land nr. Pirbright Junction. That said, the WoEML parallel would certainly help regenerate South Wilts rail-but a great deal of work will be needed to hide the line nr Tisbury (my 3rd local station), as I know quite a few people who wouldn't like a 200mph line go past every 5 mins-the diesels rattling by every hour is bad enough!!

Agreed, I think the bigger thing for the SWML would be to make a new high speed bypass within the M25 and increase line speeds further out, this coupled with 25KV OHLE (allowing 450s/444s to use 100% power draw) you should see journey times drop.

 

[po8crg]

How much impact will OHLE on Basingstoke-Southampton have on SWML times?

 

[Muzer]

I was under the impression that the Basingstoke-Southampton OHLE conversion might be rethought and perhaps not performed - wasn't it downgraded in priority in a recent report or something?

 

[59CosG95]

I was under the impression that the Basingstoke-Southampton OHLE conversion might be rethought and perhaps not performed - wasn't it downgraded in priority in a recent report or something?

2 weeks old, but this is still valid: look at Southern Region http://www.globalrailnews.com/2014/02/04/2-billion-electrification-framework-contracts-awarded/ -which implies that the SWML can still be 25kV wired! I'm sure that, if they get new motors, the 444s (or should I say 344s) would be able to reach 125mph! Unlikely but possible.

 

[Rhydgaled]

the 444s (or should I say 344s) would be able to reach 125mph! Unlikely but possible.

Not carrying passengers, the Health and Saftey pepole wouldn't allow it, I expect. Also, most >115mph stock has streamlined ends (eg. class 91s can't (or aren't allow to) do more than 110mph if running blunt-end first).

 

[TheGrew]

Not carrying passengers, the Health and Saftey pepole wouldn't allow it, I expect. Also, most >115mph stock has streamlined ends (eg. class 91s can't (or aren't allow to) do more than 110mph if running blunt-end first).

Agreed, the more useful thing for the 450s/444s would be the ability to actually reach and maintain 90+mph for much of the journey. I think in a number of places the inability to draw sufficient juice is the main problem. A couple of line speed increases would help too though.

Sent from my Nexus 4 using Tapatalk

 

[HSTEd]

If you are going to build some dedicated relief life inside the M25, I am pretty sure they would build it to high speed standards and use new CC stock.

Otherwise you can't make the most of the fifty kilometre dash.

 

[NotATrainspott]

Since HS2 effectively does the job of three mainlines, isn't it likely that the Great Western and South Western new relief/HSR lines would share a terminus and the tunnel out past the M25? I don't see passenger numbers on long-distance SWT trains being enough to justify such a large tunnel on their own, somehow. Similarly I would imagine that a dedicated London-Toton line would also take up the long-distance Anglia services.

 

[po8crg]

Since HS2 effectively does the job of three mainlines, isn't it likely that the Great Western and South Western new relief/HSR lines would share a terminus and the tunnel out past the M25? I don't see passenger numbers on long-distance SWT trains being enough to justify such a large tunnel on their own, somehow. Similarly I would imagine that a dedicated London-Toton line would also take up the long-distance Anglia services.

The Waterloo/Paddington split dating back to the GWR and L&SWR doesn't make much sense. Waterloo is the much better location, so any new line would surely terminate there (perhaps at the ex-International platforms for GC-gauge rail).

If you're running at 200mph+, a single line going Waterloo-Southampton-Bristol-Exeter is probably the most sensible solution. It's fast enough that the relatively long way around to Bristol isn't a hardship.

If you're running at 125 mph (or even 140mph with ERTMS), then you would ideally want to run a route to a dividing point, probably somewhere in Surrey or Berkshire, and then run one line to Reading for the GW route and another to Basingstoke for the SW route. If you're taking that option, then the Basingstoke-Salisbury-Yeovil route to Exeter is more attractive than Reading-Newbury-Westbury-Taunton.

I wonder what the costings would look like for these two options, ie HS3 (with the possibility of a future extension to the South Wales cities over a new Severn crossing and a future connection to HS2 with a Bristol-Birmingham line) against a new conventional line joining Basingstoke, Reading and Waterloo, and line-speed upgrades on Basingstoke-Southampton and Basingstoke-Exeter (Reading-Bristol being assumed to have been done with GWML electrification).

I'd expect that the additional costs of upgrade work on working railways would make the HS3 option pretty close in price terms, though it wouldn't relieve the Reading-Swindon commuter corridor as effectively. Getting the HSTs out of Paddington and pushing the short-distance commuters into Crossrail would make space for suburban trains using stock along the lines of 350s/450s doing Bristol-Swindon-Didcot-Reading-Paddington, while the long-distance services are all diverted to HS3.

 

[NotATrainspott]

The Waterloo/Paddington split dating back to the GWR and L&SWR doesn't make much sense. Waterloo is the much better location, so any new line would surely terminate there (perhaps at the ex-International platforms for GC-gauge rail).

If you're running at 200mph+, a single line going Waterloo-Southampton-Bristol-Exeter is probably the most sensible solution. It's fast enough that the relatively long way around to Bristol isn't a hardship.

If you're running at 125 mph (or even 140mph with ERTMS), then you would ideally want to run a route to a dividing point, probably somewhere in Surrey or Berkshire, and then run one line to Reading for the GW route and another to Basingstoke for the SW route. If you're taking that option, then the Basingstoke-Salisbury-Yeovil route to Exeter is more attractive than Reading-Newbury-Westbury-Taunton.

I wonder what the costings would look like for these two options, ie HS3 (with the possibility of a future extension to the South Wales cities over a new Severn crossing and a future connection to HS2 with a Bristol-Birmingham line) against a new conventional line joining Basingstoke, Reading and Waterloo, and line-speed upgrades on Basingstoke-Southampton and Basingstoke-Exeter (Reading-Bristol being assumed to have been done with GWML electrification).

I'd expect that the additional costs of upgrade work on working railways would make the HS3 option pretty close in price terms, though it wouldn't relieve the Reading-Swindon commuter corridor as effectively. Getting the HSTs out of Paddington and pushing the short-distance commuters into Crossrail would make space for suburban trains using stock along the lines of 350s/450s doing Bristol-Swindon-Didcot-Reading-Paddington, while the long-distance services are all diverted to HS3.

I think that the possibility of ever using Waterloo International for high-speed trains again is long gone. It was built for infrequent Class 373/Nightstar(?) services and was really just tacked on to the domestic station with only a single-lead junction connecting it to the rail network. It wasn't built for GC gauge and it is needed for SWT services.

I don't think the zigzag line is the best idea though because it would involve building almost as much track as a Y split but then slowing down journey times by some amount. For a new-build HSR line, I think a split around Reading would be ideal, with the main route continuing westwards without stopping to a/the Bristol Interchange/Parkway station and the other line stopping in Reading and other places towards Southampton/Bournemouth.

Between London and Reading, it would stop in Old Oak and then pass to the south of Heathrow without a through station there. However, a delta junction could be built to then run to the HS2 Heathrow T5 station running north-south. This is largely due to the same logic as why HS2 doesn't pass underneath/through Heathrow, as the cost of a station and tunnelling under the airport and the journey time increase involved in stopping all trains there is too great for the limited number of people who would use the station. With this delta junction and the use of the HS2 station, it would connect up HS2 and HS3 to allow any combination of services, such as Birmingham-Southampton or to allow mixing of services between Euston and the GW/SW HSR terminus in London via stopping at Heathrow. It's also a first step towards building the London orbital HSR route, which isn't a matter of if but a matter of when.

 

[HSTEd]

Stopping in Reading is pointless.
Stopping at Old Oak Common would also overload the facilities there.

Stopping at Heathrow provides a Crossrail based connection to HS2 at Old Oak but would not load everything into a single station which would cause problems for interchange passengers.
You could then provide a three way split with one branch proceeding to Bristol and South Wales, one stub to Reading to join the main line there and one line proceeding to Basingstoke.

 

[po8crg]

If we can't use Waterloo International, then expanding Waterloo would still be my preference; nowhere else has the connectivity that Waterloo has.

My argument for the zigzag is that it really isn't that much further London-Bristol (it's no worse a diversion than Birmingham on the London-Leeds line), and it gets you a South Hants-Bristol connection that you don't get from a Y-type solution.

Southampton and Bristol are only 75 miles apart, but you really wouldn't know it from their poor transport links. There's 1.5 million in the South Hants metro area, and a million in the Bristol-Bath metro area, so that's not an insignificant population to connect together.

The suggestion about an HS2-HS3 connection around Heathrow is well-taken; I'd be sorely tempted to build out to Gatwick, getting an airport-airport connection and a Gatwick-Waterloo Express.

I really wouldn't bother with an HS station at Reading. Just Southampton Airport and then Bristol. The various connections through Bristol actually make the case for a city station - there will be lines from the W/NW (Severn crossing to Wales), NE (Birmingham), E/SE (London, direct or via Southampton) and SW (Exeter) eventually. Any out-of-town station will still result in at least one line going right through Bristol, so, if you're doing major works through the city anyway, why get the benefit by putting the centre of the X in Temple Meads?

 

[JamesRowden]

The Waterloo/Paddington split dating back to the GWR and L&SWR doesn't make much sense. Waterloo is the much better location, so any new line would surely terminate there (perhaps at the ex-International platforms for GC-gauge rail).

If you're running at 200mph+, a single line going Waterloo-Southampton-Bristol-Exeter is probably the most sensible solution. It's fast enough that the relatively long way around to Bristol isn't a hardship.

If you're running at 125 mph (or even 140mph with ERTMS), then you would ideally want to run a route to a dividing point, probably somewhere in Surrey or Berkshire, and then run one line to Reading for the GW route and another to Basingstoke for the SW route. If you're taking that option, then the Basingstoke-Salisbury-Yeovil route to Exeter is more attractive than Reading-Newbury-Westbury-Taunton.

I wonder what the costings would look like for these two options, ie HS3 (with the possibility of a future extension to the South Wales cities over a new Severn crossing and a future connection to HS2 with a Bristol-Birmingham line) against a new conventional line joining Basingstoke, Reading and Waterloo, and line-speed upgrades on Basingstoke-Southampton and Basingstoke-Exeter (Reading-Bristol being assumed to have been done with GWML electrification).

I'd expect that the additional costs of upgrade work on working railways would make the HS3 option pretty close in price terms, though it wouldn't relieve the Reading-Swindon commuter corridor as effectively. Getting the HSTs out of Paddington and pushing the short-distance commuters into Crossrail would make space for suburban trains using stock along the lines of 350s/450s doing Bristol-Swindon-Didcot-Reading-Paddington, while the long-distance services are all diverted to HS3.

For the terminating capacity in central London, Crossrail 2 should hopefully produce enough space in Waterloo for a 20tph High Speed service. I think that it might not be too bad to keep to the standard 240m long British gauge trains so to maintain full flexibility over which route each service can run along. What about the following route for HS3:

Waterloo - IntoTunnel - OutOfTunnelOutSideLondon - Heathrow - An undefined distance west of Heathrow:

• GW Branchs Connects to GW at:
  • East of Reading (Reading towards Waterloo HS3)
  • West of Reading (Swindon HS3 towards Reading) Primary purpose is XC and during engineering works
  • West of Newbury (Taunton towards Waterloo HS3)
  • South of Oxford (Oxford towards Waterloo HS3)
  • West of Didcot (Swindon towards Waterloo HS3)
• LSW Branchs Connects to LSW at:
  • East of Basingstoke (Basingstoke towards Waterloo HS3)
  • West of Basingstoke (Bournemouth HS3 towards Basingstoke) Primary purpose is XC and during engineering works
  • North of Eastleigh (Eastleigh towards Waterloo HS3)
  • North of Fareham (Fareham towards Waterloo HS3)
  • West of Southampton (Bournemouth towards Waterloo HS3)

Some junctions could be built as three way to allow non-London services to Run along HS3 on the following routes when there is engineering works or disruption:

Oxford-Reading-Basingstoke-Southampton-Bournemouth (possibly using some of the HS3 bypasses to miss some of these stations)

Bournemouth-Fareham

EDIT:

I have attached a map of my idea

 

[HSTEd]

240m 'British' Gauge trains cut line capacity by half or more.

That (at least) doubles the effective cost of the solution.

 

[NotATrainspott]

Stopping in Reading is pointless.
Stopping at Old Oak Common would also overload the facilities there.

Stopping at Heathrow provides a Crossrail based connection to HS2 at Old Oak but would not load everything into a single station which would cause problems for interchange passengers.
You could then provide a three way split with one branch proceeding to Bristol and South Wales, one stub to Reading to join the main line there and one line proceeding to Basingstoke.

I agree that stopping South Wales/West Country HSR trains in Reading is silly, so they would just bypass it completely. However, trains heading down to Southampton and beyond make more sense stopping there because the current journey times are long and the complete journey isn't long enough to justify a non-stop service like South Wales/Bristol or the HS2 routes do. It's likely that a SW HSR line would use classic-compatibles until well into the future so if there is capacity at the existing stations, it would be sensible to use them rather than to have to build dedicated ones at great cost.

Whether stopping at Old Oak is a good idea depends most of where the interchange station makes most sense. Stopping at Heathrow for Crossrail has the disadvantage that it is only capable of feeding into Crossrail, the Piccadilly line, the future WRAtH and son-of-Airtrack lines, whereas Old Oak has the advantage of being like Stratford where many more lines will be built to connect it into the transport network. Old Oak can develop into a station site on the scale of Euston-Kings'-Cross-St-Pancras, which is capable of dealing with its number of passengers with Victorian infrastructure. Depending on where the central London station were placed, interchanging to Crossrail at Heathrow also has the disadvantage that it would increase journey times into London on Crossrail by a considerable amount unless the Heathrow Express paths were kept on the fast lines before going into tunnel and faster Aventra stock were ordered specially to keep up with the IEPs.

 

[JamesRowden]

240m 'British' Gauge trains cut line capacity by half or more.

That (at least) doubles the effective cost of the solution.

Since no new stations (apart from Heathrow) would need to be built, no new tunnels outside London (apart from possibly Heathrow and possibly the odd one to go through a hill) would be required for existing stations (e.g. an extra platform to two), I think that it would greatly reduce the cost of the project.

Also, would there be enough demand to justify 400m trains to all of the destinations?

 

[HSTEd]

Since no new stations (apart from Heathrow) would need to be built, no new tunnels outside London (apart from possibly Heathrow and possibly the odd one to go through a hill) would be required for existing stations (e.g. an extra platform to two), I think that it would greatly reduce the cost of the project.

Not really, you would still have to drastically reconstruct the stations concerned to deal with the inevitable surge in passengers.
And if you don't construct any new platforms at any outlying stations you won't actually generate any extra capacity and would just be trading trains on the old line for trains on the new line one-for-one.

We are rather heavily Platform constrained.

Also, would there be enough demand to justify 400m trains to all of the destinations?

Considering 240m trains now are heavily loaded, its not unreasonable to expect 400m Double decks to be required on many services rapidly after capacity constraints are moved, journey times collapse and season ticket prices stop skyrocketing.
--- old post above --- --- new post below ---

I agree that stopping South Wales/West Country HSR trains in Reading is silly, so they would just bypass it completely. However, trains heading down to Southampton and beyond make more sense stopping there because the current journey times are long and the complete journey isn't long enough to justify a non-stop service like South Wales/Bristol or the HS2 routes do.

Even if we were to run trains non stop to Southampton, that is still something approaching a hundred miles, its not so short as to make a non stop journey seem ridiculous.
They would clearly stop at whatever hub station has been selected on the outskirts of london but I see no reason to force them to stop again just to extend journey time.
There would likely be through trains to Weymouth (even if many trains would be double decks unable to proceed beyond southampton) which would extend journey time.

And remember with shorter journey times we can increase capacity by fitting interiors suited to such short journeys.

It's likely that a SW HSR line would use classic-compatibles until well into the future so if there is capacity at the existing stations, it would be sensible to use them rather than to have to build dedicated ones at great cost.

It is unlikely that there is sufficient spare capacity at these stations which are already heavily constrained.
And upgrading them will probably turn out to be almost expensive as new construction would be, if it is cleverly planned.

Whether stopping at Old Oak is a good idea depends most of where the interchange station makes most sense. Stopping at Heathrow for Crossrail has the disadvantage that it is only capable of feeding into Crossrail, the Piccadilly line, the future WRAtH and son-of-Airtrack lines, whereas Old Oak has the advantage of being like Stratford where many more lines will be built to connect it into the transport network.

As those lines have not yet been built or even mooted, its a little early to ascribe that as a benefit to OOC that cannot be transferred to nearly any part of London I care to name

OOC also has the disadvantage that the only practical terminal for a Western High Speed line is Paddington, the Waterloo approach is a collosal mess and all the other sites are far too constrained.

increase journey times into London on Crossrail by a considerable amount unless the Heathrow Express paths were kept on the fast lines before going into tunnel and faster Aventra stock were ordered specially to keep up with the IEPs.

Why are the IEPs even still running?
If we have a Reading connection the need for superfast intercity services on the normal GWML dissapears, we can easily dispatch a pair of coupled CC sets a couple of times per hour which can pick up all the Oxford fasts and all the minor destinations on eroute to Bristol.

We have 18 paths an hour to play with remember.

 

[NotATrainspott]

Even if we were to run trains non stop to Southampton, that is still something approaching a hundred miles, its not so short as to make a non stop journey seem ridiculous.
They would clearly stop at whatever hub station has been selected on the outskirts of london but I see no reason to force them to stop again just to extend journey time.
There would likely be through trains to Weymouth (even if many trains would be double decks unable to proceed beyond southampton) which would extend journey time.

And remember with shorter journey times we can increase capacity by fitting interiors suited to such short journeys.

However, Southampton is closer to London than Birmingham is and it's nowhere near the same size. If you don't stop anywhere in between, you need to be able to guarantee you would fill a few trains an hour, which is quite probably something that wouldn't be possible for some time even after a capacity and demand boom. High Speed 1 works just fine with stops at Stratford, Ebbsfleet and Ashford and it's of similar length as a Southampton line. With the number of paths available on a new line, and the massive increase in speed even when stopping, there wouldn't be any issue stopping at intermediate stations as there is on HS2 where stopping at Milton Keynes or Calvert/Chilterns would ruin the journey time savings and cause unnecessary congestion.

It is unlikely that there is sufficient spare capacity at these stations which are already heavily constrained.
And upgrading them will probably turn out to be almost expensive as new construction would be, if it is cleverly planned.

In some locations the high-speed ones would effectively replace the classic ones, so it's not always going to be that big a problem. The main capacity issue on the former NSE lines is the London ends, which would always get new stations on HSR lines. However, if there are locations where a new station is required then that can be factored in to the design of the line.

As those lines have not yet been built or even mooted, its a little early to ascribe that as a benefit to OOC that cannot be transferred to nearly any part of London I care to name

OOC also has the disadvantage that the only practical terminal for a Western High Speed line is Paddington, the Waterloo approach is a collosal mess and all the other sites are far too constrained.

No, there are definite aspirations to modify the Overground to connect with Old Oak at the moment, and Network Rail want to put the local WCML routes through Old Oak onto Crossrail as well. Unless Heathrow is abandoned and turned into a new borough/garden city, it will forever remain an airport where there is not the need for the kind of local transit which makes development zones like Canary Wharf or soon to be the Park Royal city special.

Why are the IEPs even still running?
If we have a Reading connection the need for superfast intercity services on the normal GWML dissapears, we can easily dispatch a pair of coupled CC sets a couple of times per hour which can pick up all the Oxford fasts and all the minor destinations on eroute to Bristol.

We have 18 paths an hour to play with remember.

On second thoughts it does seem unlikely that there would be many non-stop IEP paths past Heathrow left after a dedicated line is built. However, Heathrow is still much further from central London and has the disadvantage that it wouldn't ever be served by the Crossrail 'core' at 24tph. Once HS2 opens, the core will expand westwards from Paddington to Old Oak so that HS2 passengers won't have to compete for space on the train with people from Heathrow or Maidenhead. Doing the same for Heathrow would be too expensive for the number of passengers using it.

 

[HowardGWR]

It seems to me that there are far too many solutions chasing an envisaged need. I agree that an HSL from Southampton to Bristol (and then to Wales or Brum and points north) looks commercially and strategically justified, in advance of analysis of possible flows. London to Southampton and then on to Bristol looks like two separate flows to me, as I just don't believe that London to Southampton HSl is politically 'on' or needed, if IEP service was provided on an updated route, possibly via Reading to OOC and PAD.

That brings me to solutions. As I have just written, I challenge anyone to get out his crayon and devise an HSL from OOC or LHR route to Southampton, that would be politically acceptable.

It gets worse when considering Southampton to Bristol. The possible route is across several AsONB (Areas of Outstanding Natural Beauty), not to mention the topographical aspect of getting over or through the vast hills of Salisbury Plain and Mendips. How long do you want your tunnels?

It would make the Chilterns protests seem a mere local difficulty.

 

[JamesRowden]

It seems to me that there are far too many solutions chasing an envisaged need. I agree that an HSL from Southampton to Bristol (and then to Wales or Brum and points north) looks commercially and strategically justified, in advance of analysis of possible flows. London to Southampton and then on to Bristol looks like two separate flows to me, as I just don't believe that London to Southampton HSl is politically 'on' or needed, if IEP service was provided on an updated route, possibly via Reading to OOC and PAD.

That brings me to solutions. As I have just written, I challenge anyone to get out his crayon and devise an HSL from OOC or LHR route to Southampton, that would be politically acceptable.

It gets worse when considering Southampton to Bristol. The possible route is across several AsONB (Areas of Outstanding Natural Beauty), not to mention the topographical aspect of getting over or through the vast hills of Salisbury Plain and Mendips. How long do you want your tunnels?

It would make the Chilterns protests seem a mere local difficulty.

The London and South East RUS predicts that there will be over crowding on the GWML between Reading and Paddington by 2031 even with a 20tph service on the fast tracks made up of Intercity services and 12-car Thames Valley EMUs. This level of service is only possible if Heathrow Express is removed from the fast tracks during the peak. I would not be suprised if the route via Woking would be in a worse position.

If these predictions are correct, do you have a better option than the construction of new a High Speed Line or do think that the 'do nothing' approach is the best option?

 

[MarkyT]

. . . I challenge anyone to get out his crayon and devise an HSL from OOC or LHR route to Southampton, that would be politically acceptable.

Perhaps better to rebuild the existing route for 4 tracks all the way from Basingstoke to Southampton. It is fairly straight and very direct and 4 tracks could nicely segregate more frequent faster expresses from increased stoppers and freight, and be more flexible and resilient.

 

[The Ham]

Perhaps better to rebuild the existing route for 4 tracks all the way from Basingstoke to Southampton. It is fairly straight and very direct and 4 tracks could nicely segregate more frequent faster expresses from increased stoppers and freight, and be more flexible and resilient.

Why not just four track from Reading to Southampton and run CC stock from (for example) Paddington to Basingstoke then split it with half going to Weymouth via Southampton and the other half going to Salisbury. You would probably need to rebuild Basingstoke to do away with the flat junction, but that maybe required by then anyway.

 

[NotATrainspott]

It seems to me that there are far too many solutions chasing an envisaged need. I agree that an HSL from Southampton to Bristol (and then to Wales or Brum and points north) looks commercially and strategically justified, in advance of analysis of possible flows. London to Southampton and then on to Bristol looks like two separate flows to me, as I just don't believe that London to Southampton HSl is politically 'on' or needed, if IEP service was provided on an updated route, possibly via Reading to OOC and PAD.

That brings me to solutions. As I have just written, I challenge anyone to get out his crayon and devise an HSL from OOC or LHR route to Southampton, that would be politically acceptable.

It gets worse when considering Southampton to Bristol. The possible route is across several AsONB (Areas of Outstanding Natural Beauty), not to mention the topographical aspect of getting over or through the vast hills of Salisbury Plain and Mendips. How long do you want your tunnels?

It would make the Chilterns protests seem a mere local difficulty.

The logic behind HS2 applies equally well to any other line once all sensible upgrade options are expended. Once there's OHLE, speed increases and as many tracks as it is reasonably possible for there to be on the route the only sensible decision is to build new lines, which again would be much better being high-speed.

 

[HowardGWR]

The London and South East RUS predicts that there will be over crowding on the GWML between Reading and Paddington by 2031 even with a 20tph service on the fast tracks made up of Intercity services and 12-car Thames Valley EMUs. This level of service is only possible if Heathrow Express is removed from the fast tracks during the peak. I would not be suprised if the route via Woking would be in a worse position.

If these predictions are correct, do you have a better option than the construction of new a High Speed Line or do think that the 'do nothing' approach is the best option?

I think RDG to PAD will probably go to 6 tracks.
--- old post above --- --- new post below ---

Perhaps better to rebuild the existing route for 4 tracks all the way from Basingstoke to Southampton. It is fairly straight and very direct and 4 tracks could nicely segregate more frequent faster expresses from increased stoppers and freight, and be more flexible and resilient.

Yes I think that may be pragmatically the best way.

 

[MarkyT]

I think RDG to PAD will probably go to 6 tracks

Perhaps, but maybe only as far as Maidenhead, after which Relief line stations become much sparser, and you've got a Welwyn plus sized problem through the Ealing bottleneck and across Wharncliffe viaduct, then there's all those listed structures and station buildings . . .

 

[TheGrew]

Perhaps better to rebuild the existing route for 4 tracks all the way from Basingstoke to Southampton. It is fairly straight and very direct and 4 tracks could nicely segregate more frequent faster expresses from increased stoppers and freight, and be more flexible and resilient.

You might struggle with that approach at Winchester where the line runs in a cutting right through the centre of town. Admittedly everything minus freight is scheduled to stop their but I believe this is one of the main capacity constraints on the line, the other being the popham tunnels.

 

[59CosG95]

You might struggle with that approach at Winchester where the line runs in a cutting right through the centre of town. Admittedly everything minus freight is scheduled to stop there but I believe this is one of the main capacity constraints on the line, the other being the popham tunnels.

Would a two-tiered track be a solution? (i.e. having the fast tracks over the stopping tracks from just south of the cutting to about a mile north of the station) It could solve the cutting capacity problem and allow full segregation of expresses/freight and stoppers in one fell swoop. As for the tunnels, a "Watford" situation can be developed, with the down fast and slows in one twin tunnel (the new one, (bored to the east of the existing tunnel, near the disused oil terminal) and the up fast and slows in the existing bores. As for the Civic Centre Tunnel, a new tunnel could probably be bored to the north of the existing one, with re-retaining done as necessary.

 

[MarkyT]

Would a two-tiered track be a solution? (i.e. having the fast tracks over the stopping tracks from just south of the cutting to about a mile north of the station) It could solve the cutting capacity problem and allow full segregation of expresses/freight and stoppers in one fell swoop.

There was another north-south railway through Winchester, the former GWR line through Chesil station. A independent freight bypass route approximating that lower speed line could leave the existing line to the various passenger services, stopping or not, and avoid having to widen or double deck the existing alignment. Whilst much of the Chesil route to the south is not built over significantly through the urban area, there is a large multi-storey car park on the former station site and an access road to it from the south (Barfield Close). North of the station tunnel, the alignment emerges into what is now a quiet housing estate before entering an industrial area however and some housing has been built over the track bed (Fiona Close), so that route is probably difficult if not impossible.

Perhaps the biggest obstacle is through the 'Worthys' where the former GWR alignment was taken over by the dual carriageway A34. It might be possible to squeeze a lower speed rail alignment back in alongside the busy, noisy road, but proximity to such large roads has the risk of entailing very expensive and disruptive roadworks.

If the Worthys could be overcome an alternative to the Chesil route might be following the M3 motorway route around the east, then cutting back across the old bypass route to rejoin the Chesil connection line to the LSWR. Is Swampy still out there?

As for the tunnels, a "Watford" situation can be developed, with the down fast and slows in one twin tunnel (the new one, (bored to the east of the existing tunnel, near the disused oil terminal) and the up fast and slows in the existing bores.

Good solution - the actual line directions and designations would probably depend on the optimal arrangements at adjacent junctions and station at Basingstoke and Winchester/ Eastleigh and any intermediate 'weaves'

As for the Civic Centre Tunnel, a new tunnel could probably be bored to the north of the existing one, with re-retaining done as necessary.

I don't think it's neccessary to insist on four tracks all the way through to Southampton Central station itself. The primary objective would be Eastleigh and the airport, where freights can be regulated and slotted into the altogether slower general traffic beyond, There are some difficult sections south of the airport, under the M27 bridge for example, which was built shortsightedly for only 2 tracks. Nevertheless as part of such a large scheme it would be sensible to reconstruct or add a bore to the Civic Centre tunnel, adding at least 1 extra local approach track to help the fairly small station cope with traffic increases, in particular allowing a down passenger train to be held close to the platforms whilst a freight overtakes it, then 'nipping in' after it.