HS2 construction updates

[Bletchleyite]

If it was up to me, I'd have looked at an interchange station between HS2 and East West Rail. That would have a use beyond appeasing locals and making HS2 useful to people along the line would be a bonus.

Verney Junction Parkway?

 

[Jozhua]

Except they saw benefits - ability to get to the motorway and reduced local town traffic in some cases I expect as the M40 is a huge long bypass, it certainly helped towns like Southam and Banbury. There's zero benefit on HS2 for Chilterns - it flies through non-stop.

Well, apart from all the released capacity on the WCML and paths into London, which will result in better service for the Chilterns.

Although you did say on HS2. I guess reality is meaningless if it isn't perceived in that way

 

[Bletchleyite]

Well, apart from all the released capacity on the WCML and paths into London, which will result in better service for the Chilterns.

Although you did say on HS2. I guess reality is meaningless if it isn't perceived in that way

I'm forever shouting that HS2 will not only benefit MK, but that MK is the main reason for even building Phase 1 - but people still don't get it. Chiltern isn't likely to see a "metro style" London services off the back of HS2 (but that is proposed for MK) so you can see why that's even harder to sell, particularly as unlike MK it is "in their back yard".

 

[Ianno87]

I'm forever shouting that HS2 will not only benefit MK, but that MK is the main reason for even building Phase 1 - but people still don't get it. Chiltern isn't likely to see a "metro style" London services off the back of HS2 (but that is proposed for MK) so you can see why that's even harder to sell, particularly as unlike MK it is "in their back yard".

An interesting theoretical exercise would be what would the Chiltern timetable look like if it were less designed around chasing Birmingham-London revenue.

 

[Bletchleyite]

An interesting theoretical exercise would be what would the Chiltern timetable look like if it were less designed around chasing Birmingham-London revenue.

That sounds like an interesting thread in its own right: https://www.railforums.co.uk/threads/chiltern-timetable-what-if-it-wasnt-about-brum-london.213772/

 

[edwin_m]

If it was up to me, I'd have looked at an interchange station between HS2 and East West Rail. That would have a use beyond appeasing locals and making HS2 useful to people along the line would be a bonus.

With the intensity of operation of this part of the HS2, every train calling at such a station would result in one train fewer between London and Birmingham, unless at least a third of trains stopped which would be far in excess of the demand.

Interchange with EWR may look useful at first glance. But doing the numbers it's evident that from Bicester or MK or anywhere beyond, it would be quicker to travel to London or Birmingham by existing routes without the hassle of changing trains. So interchange would be limited to people making very short journeys on EWR, and to justify the new station there would have to be settlement around Calvert getting towards the size of MK. Or perhaps a future main London airport. I think the locals would find either of those far less palatable than HS2.

 

[miami]

If it was up to me, I'd have looked at an interchange station between HS2 and East West Rail. That would have a use beyond appeasing locals and making HS2 useful to people along the line would be a bonus.

If tied in with a new airport, and be a termination of an extension of the Aylesbury line, it might have made sense.

But I fail to see what this has to do with construction of HS2. In actual construction related news:

Protests at Euston continue, yesterday they applied for an injunction which was not only refused, the court ordered the protesters to tell authorities the layout and size of the tunnels! There's reports of 5 people still underground.

There was a minor protest involving climbing walls this morning too. I don't think they are getting the type of media traction they would hope for.

 

[GRALISTAIR]

Look at all the resistance to EWR, a perfectly normal two track railway, as it approaches Cambridge. Sometimes NIMBYs gotta NIMBY.

Exactly

 

[quantinghome]

What it comes down to is that there is no long term overarching plan for the railways as there is in Switzerland or Germany. HS2 is as close as we have to one, but the government have not taken the next step and actually defined the service improvements for the 'classic' network beyond broad brush strokes. The argument may be 'it's too far in the future to make a plan' but that's not stopping other countries. You make the plan and then change it if needed.

If there was a plan, you could say to folk in the Chilterns, "as part of the national railway plan we will be improving your local rail service by doing X Y Z". Then when the complaints roll in about HS2, the simple answer would be "it's all part of the national railway plan, it's all connected, we can't do X Y Z without building HS2".

 

[CW2]

The question of an interchange station between HS2 and the (then) entirely putative EWR was looked at in some detail.

As it would be right in the middle of the highest-speed section of HS2, any stop would consume more than one additional train path, because of the time taken to decelerate from full speed and accelerate back up to full speed - and of course the end-to-end journey times would be extended by the same amount + station dwell. Since the number of paths is limited, a choice would come down to something like "Do we stop one train per hour at Chiltern Parkway and accept longer journey times on subsequent services or run an additional train to (say) Leeds." If the likely interconnecting traffic had been strong, then it would still have been a tricky case to make. Remember an HS2 loop serving Heathrow Airport was ditched on much the same logic.

There could never be sufficient traffic at Chiltern Interchange to justify stopping any high speed trains there.

Obviously this makes selling the case for HS2 to the locals all the more tricky - but I suspect they would have been against it regardless.

 

[Watershed]

As it would be right in the middle of the highest-speed section of HS2, any stop would consume more than one additional train path, because of the time taken to decelerate from full speed and accelerate back up to full speed - and of course the end-to-end journey times would be extended by the same amount + station dwell. Since the number of paths is limited, a choice would come down to something like "Do we stop one train per hour at Chiltern Parkway and accept longer journey times on subsequent services or run an additional train to (say) Leeds." If the likely interconnecting traffic had been strong, then it would still have been a tricky case to make. Remember an HS2 loop serving Heathrow Airport was ditched on much the same logic.

It wouldn't necessarily have to limit line capacity at all. You just have to four-track the line for a sufficient distance either side of the station, and have four platforms at the station.

Obviously that would mean even greater land take and cost, so it makes the BCR for a Chiltern Parkway even weaker.

 

[Ianno87]

It wouldn't necessarily have to limit line capacity at all. You just have to four-track the line for a sufficient distance either side of the station, and have four platforms at the station.

Obviously that would mean even greater land take and cost, so it makes the BCR for a Chiltern Parkway even weaker.

Not correct.

With 18tph, each calling train needs to vacate one path south of the station, and then re-enter a second path after departing, so each calling path consumes two paths in total.

The only way to avoid this is to have two platforms per direction and stop absolutely everything. Which means slowing down every passenger to/from London for the benefit of a relative minority joining at "Chiltern Parkway".

 

[CW2]

Not correct.

With 18tph, each calling train needs to vacate one path south of the station, and then re-enter a second path after departing, so each calling path consumes two paths in total.

The only way to avoid this is to have two platforms per direction and stop absolutely everything. Which means slowing down every passenger to/from London for the benefit of a relative minority joining at "Chiltern Parkway".

... and because of the speeds involved, the braking phase will cause the train behind to be delayed, and the acceleration phase will cause the next train behind to catch up and have to slow down.

 

[The Planner]

200mph S&C anyone?

 

[miami]

With 18tph, each calling train needs to vacate one path south of the station, and then re-enter a second path after departing, so each calling path consumes two paths in total.

Couldn't you try to time it so that a train leaving Verney filled the slot that was just left?

 

[CW2]

Couldn't you try to time it so that a train leaving Verney filled the slot that was just left?

No. The trains are running at 3-minute intervals, with a couple per hour left spare for contingencies. The slot it has vacated is proceeding south at 300+ kph. By the time you come to a stop, the following slot is right behind you, or already overtaken you. While you stop for a couple of minutes, a third slot is fast approaching. Once you accelerate, you might just about make it into the fourth slot, but no guarantees.

 

[quantinghome]

200mph S&C anyone?

Out of interest what limits current designs to 140mph turnout speed?

 

[Bald Rick]

200mph S&C anyone?

I thought that!

 

[Ianno87]

Out of interest what limits current designs to 140mph turnout speed?

AIUI (and may be wrong), the angle of the crossing becomes so shallow it just doesn't work.

 

[edwin_m]

There are intended to be 225km/h turnouts where the 4-track section starts/ends south of Birmingham Interchange, and the headway can be adjusted far enough from the nominal 3min that a northbound stopping train can diverge at this speed without delaying the following non-stop. So in principle you could do this at a Chiltern station too, but for maximum capacity you'd have to stop every third or fourth train - @CW2 I think it would be the third because if I recall correctly the stop-start penalty is 5min plus dwell time so it should make it back into the slot 9min later. I believe Japan does something like this with its mix of fast and slightly less fast trains on the Shinkansen.

 

[Ianno87]

There are intended to be 225km/h turnouts where the 4-track section starts/ends south of Birmingham Interchange, and the headway can be adjusted far enough from the nominal 3min that a northbound stopping train can diverge at this speed without delaying the following non-stop. So in principle you could do this at a Chiltern station too, but for maximum capacity you'd have to stop every third or fourth train - @CW2 I think it would be the third because if I recall correctly the stop-start penalty is 5min plus dwell time so it should make it back into the slot 9min later. I believe Japan does something like this with its mix of fast and slightly less fast trains on the Shinkansen.

That is how the "stoppers" on the Tokaido Shinkansen work, but only with a maximum of 15tph per direction, and a fully self-contained line.

 

[edwin_m]

That is how the "stoppers" on the Tokaido Shinkansen work, but only with a maximum of 15tph per direction, and a fully self-contained line.

Indeed. It would also increase the vulnerability to trains arriving from Network Rail in the wrong order. Currently if one presents late it can drop into the next available slot on HS2 with following trains delayed by decreasing amounts of 3min or less until it all catches up. That wouldn't work if they had different stopping patterns.

 

[Bald Rick]

AIUI (and may be wrong), the angle of the crossing becomes so shallow it just doesn't work.

That can be, and is, solved by swing nose crossings (required for any turnout on any line above 125mph here, regardless of turnout speed).

However a higher turnout speed results in much longer switch rails, the movable section of which is the problem. It will require multiple drive mechanisms and very precise handling and maintenance.

 

[ABB125]

200mph S&C anyone?

On first reading this, I thought "Settle and Carlisle"

 

[miami]

No. The trains are running at 3-minute intervals, with a couple per hour left spare for contingencies. The slot it has vacated is proceeding south at 300+ kph. By the time you come to a stop, the following slot is right behind you, or already overtaken you. While you stop for a couple of minutes, a third slot is fast approaching. Once you accelerate, you might just about make it into the fourth slot, but no guarantees.

Surely depends on the length of the acceleration and deceleration lanes and dwell times.

Assume 20tph every 3 minutes, 6km/minute, Verney is at 90km, deceleration lane starts at 66km, acceleration lane ends at 126km, points can run at line speed, dwell time of 12 minutes and stop 4 trains per hour.

Of course that's a hell of a lot of land and complicated switching mechanisms, but if you say stop every 3rd train, with a dwell of 6 minutes you can fit them in without losing paths. The train that stops (the 10:00 departure) is overtaken by the 10:03 and 10:06 fasts, then the 10:09 stops and the 10:00 takes its path

Heading north, before Verney you'd have departures at 1000, 1003, 1006 etc.

After Verney the order would be

1003 Manchester
1006
1000 (taking the 1009 slot)
1012
1015
1009 (taking the 1018 slot)
1021
1024
1018 (taking the 1027 slot)
1030
1033
1027 (taking the 1036 slot)
1039
1042
1036 (taking the 1045 slot)
1048
1051
1045 (taking the 1054 slot)
1057
1100
1054 (taking the 1103 slot)

Repeating every 3 hours.

It might work if there was a good reason to stop at Verney on occasion (say a large London+Birmingham replacement airport which could justify 6tph from north and south at the cost of slowing and the added maintenance and land take)



Still confused why this conversation is happening in "HS2 Construction" and not speculative ideas though.

 

[Ianno87]

Surely depends on the length of the acceleration and deceleration lanes and dwell times.

Assume 20tph every 3 minutes, 6km/minute, Verney is at 90km, deceleration lane starts at 66km, acceleration lane ends at 126km, points can run at line speed, dwell time of 12 minutes and stop 4 trains per hour.

Of course that's a hell of a lot of land and complicated switching mechanisms, but if you say stop every 3rd train, with a dwell of 6 minutes you can fit them in without losing paths. The train that stops (the 10:00 departure) is overtaken by the 10:03 and 10:06 fasts, then the 10:09 stops and the 10:00 takes its path

Heading north, before Verney you'd have departures at 1000, 1003, 1006 etc.

After Verney the order would be

1003 Manchester
1006
1000 (taking the 1009 slot)
1012
1015
1009 (taking the 1018 slot)
1021
1024
1018 (taking the 1027 slot)
1030
1033
1027 (taking the 1036 slot)
1039
1042
1036 (taking the 1045 slot)
1048
1051
1045 (taking the 1054 slot)
1057
1100
1054 (taking the 1103 slot)

Repeating every 3 hours.

It might work if there was a good reason to stop at Verney on occasion (say a large London+Birmingham replacement airport which could justify 6tph from north and south at the cost of slowing and the added maintenance and land take)



Still confused why this conversation is happening in "HS2 Construction" and not speculative ideas though.

Stopping "every third train" is still (in all likelihood) negatively impacting more passengers than it benefits, with a complex operation that pretty much would have to run spot on time to have a chance of working.

 

[vic-rijrode]

The obvious answer to serving a Chilterns Parkway, without losing any train paths, is the reintroduction of slip coaches, which could be detached when approaching Calvert and diverted into the loop line serving the platform. After passengers have detrained or joined, it would then be reattached to a following train by a loco (from a slip siding) buffering up behind the slip coach and pushing it out behind the passing train. Of course the loco would have to be able to run faster than the train it was catching, which shouldn't be a problem with the new generation of hydrogen powered engines. I don't know why anybody else has thought of this solution - seems obvious to me....

 

[Yindee8191]

The obvious answer to serving a Chilterns Parkway, without losing any train paths, is the reintroduction of slip coaches, which could be detached when approaching Calvert and diverted into the loop line serving the platform. After passengers have detrained or joined, it would then be reattached to a following train by a loco (from a slip siding) buffering up behind the slip coach and pushing it out behind the passing train. Of course the loco would have to be able to run faster than the train it was catching, which shouldn't be a problem with the new generation of hydrogen powered engines. I don't know why anybody else has thought of this solution - seems obvious to me....

Clearly the slip coaches should be brought back to line speed by putting them through a small Hyperloop system which allows for very fast acceleration.

 

[ABB125]

Clearly the slip coaches should be brought back to line speed by putting them through a small Hyperloop system which allows for very fast acceleration.

Or maglev

 

[vic-rijrode]

Clearly the slip coaches should be brought back to line speed by putting them through a small Hyperloop system which allows for very fast acceleration.

Of course, how silly of me.....