Could the new Stevenage platform 5 be turned into a loop platform?

[cle]

Moderator note: Split from https://www.railforums.co.uk/threads/stevenage-platform-5.146540/

How much additional work would it be to do the full P5 Hertford works (i.e. through, not bay) compared to future possessions?

If it was done, what flexibility would it open up? Even if a service on the slow used P5 to allow one behind it to go in front, there would often be a Hertford Loop service in P5 turning back. So other than an option for when things go wrong, what would the purpose be?

Perhaps turning a Thameslink or Kings Cross train per hour, if timed up ok with the Hertfords? But I can't see how it could access the Up Slow to return south.

 

[malc-c]

I've posed the question to one of the engineers who worked on the signalling. Now it may well be that his section dealt with switches and track circuits rather than signalling itself, but hopefully he may be able to find out.

In the video at 12:00 on the timeline it was explained to me that what looks like fish plates was an insulated block joint (IBJ), but we didn't go into it any further in its function as to what it actually isolated, but I'm guessing as it was so near the platform (near six-hills bridge) that it was more to do with train detection than signalling.

 

[malc-c]

How much additional work would it be to do the full P5 Hertford works (i.e. through, not bay) compared to future possessions?

If it was done, what flexibility would it open up? Even if a service on the slow used P5 to allow one behind it to go in front, there would often be a Hertford Loop service in P5 turning back. So other than an option for when things go wrong, what would the purpose be?

Perhaps turning a Thameslink or Kings Cross train per hour, if timed up ok with the Hertfords? But I can't see how it could access the Up Slow to return south.

Personally, I can't see any advantage in making the the turnback a through line and then connecting it to the down slow north of the station, other than allowing any freight trains routed via the Hertford loop to "undertake" any north bound trains stopped in platform 4, rather than being held at Langley junction (or just after) for the down slow to become free. As for crossing over to run on the up slow and then branch off to Hertford, that would mean finding a gap over the other four lines so the train could make the crossing. But as it stands there is no means to cross over the two fast lines south of the station. Any train needing to do so would have to go north, to a point just north of Fairlands bridge, first onto the down slow, then down fast, then head south onto up fast and then to the up slow, head back through the station and then take the Hertford loop.... Can't see that being a regular happening myself

 

[Aictos]

Indeed it just be easier to terminate in Platform 4 or 5 and head back to London via the Hertford Loop.

The other thing as well is it would ease congestion especially in disruption because any fast service diverted via the Hertford loop can’t access the Down Fast until it’s passed though Plat 4.

Now if Plat 5 was a though line, you could still route the fast service though Plat 4 and signal the service calling at Stevenage to use Plat 5 by which time the Down Slow should be able to have a route set.

Neither train gets delayed with the exception of being diverted via Hertford.

It also has the benefit of being able to hold two freights, one at Platform 5 and one at Langley Jcn while a semi fast uses Plat 4 etc.

Basically if the provision is there and it’s not going to cost much more then I think yes it should be a though line.

 

[mr_jrt]

Presumably the Hertford lines are bidi signalled for the bay? That would enable any terminating Thameslink to run into p5, then reverse over the flyover, then run into p1 without fouling the fast lines at all. The addition of a new p0 could make things very seamless

...but I suspect a new chord from the up and down Hertford to the up slow would be a better solution as that Thameslink could just head south without the palaver of reversing back into p1.

 

[John R]

Presumably the Hertford lines are bidi signalled for the bay? That would enable any terminating Thameslink to run into p5, then reverse over the flyover, then run into p1 without fouling the fast lines at all. The addition of a new p0 could make things very seamless

...but I suspect a new chord from the up and down Hertford to the up slow would be a better solution as that Thameslink could just head south without the palaver of reversing back into p1.

We're getting a bit carried away here, aren't we. Have a look at the satellite imagery on google maps and consider the fact that there is the grade separation to overcome too (it's an diveunder by the way, not a flyover), and you'll see that the chord you suggest would not be cheap, assuming you mean it to be to the east of the mainline, which would be the only sensible place, to prevent occupation of the fast lines.

And to what end? Since the Hitchin flyover was built there's a perfectly good place for any mainline trains to crossover and return (Letchworth) which doesn't block the main lines and serves two additional major communities. There's really no need for anything more than the scheme which is currently in progress. It's a "solution" to a problem which doesn't exist.

Similarly the talk of making Platform 5 into a through route, given the current service level.

 

[Aictos]

Presumably the Hertford lines are bidi signalled for the bay? That would enable any terminating Thameslink to run into p5, then reverse over the flyover, then run into p1 without fouling the fast lines at all. The addition of a new p0 could make things very seamless

...but I suspect a new chord from the up and down Hertford to the up slow would be a better solution as that Thameslink could just head south without the palaver of reversing back into p1.

What flyover? The only flyovers that could be considered near to the area is at Hitchin and Welwyn GC.

There is a diveunder at Langley Junction BUT the Up Slow is not bidirectional unlike the Down Slow as far as Plat 4 at Stevenage.

Also that new chord wouldn’t help at all as you still have to cross the Down and Up fast lines.

A easier solution would be to just reverse at Langley Junction and run bi directional into Plat 1 but that is cost that is not acceptable to bean counters so I suggest that anything terminating at Stevenage using Plat 4/5 just has to head back to London via Hertford.

 

[malc-c]

Interesting discussion going on here.. One thing that did cross my mind is once platform 5 is operational would there be any need to retain bidirectional running on the down slow section between platform 4 and Langley Junction? I guess if its already wired as such then no need to change, but unless the turnback was out of commission, all trains on the down slow will be north bound with no need to head back south.

 

[Fred26]

Interesting discussion going on here.. One thing that did cross my mind is once platform 5 is operational would there be any need to retain bidirectional running on the down slow section between platform 4 and Langley Junction? I guess if its already wired as such then no need to change, but unless the turnback was out of commission, all trains on the down slow will be north bound with no need to head back south.

I suppose you could potentially have a South bound train in both of platform (4&5) during engineering work - say if the mainline is closed north of Stevenage. But that all depends on a specific set of circumstances, really, since you'll get different plans for different works.

 

[Aictos]

Interesting discussion going on here.. One thing that did cross my mind is once platform 5 is operational would there be any need to retain bidirectional running on the down slow section between platform 4 and Langley Junction? I guess if its already wired as such then no need to change, but unless the turnback was out of commission, all trains on the down slow will be north bound with no need to head back south.

Well seeing as Gordon Hill still has OHL for Platform 4 yet no track I can't see any reason not to retain the bidirectional running on the down slow between Stevenage and Langley Junction especially as there are no real advantages to removing it.

I suppose you could potentially have a South bound train in both of platform (4&5) during engineering work - say if the mainline is closed north of Stevenage. But that all depends on a specific set of circumstances, really, since you'll get different plans for different works.

Well seeing as Platform 5 won't be any longer for now then 6 coaches, you could time a stopping service (from Platform 5 formed of a Class 717) to follow a non stop service (from Platform 4 formed of a 8 or 12 Class 700) via Hertford but that's really time for another discussion.

More to the point in any case, if they do decide to extend the turnback and connect it at the north end to the Down Slow to form a loop, would they consider extending the platform to take a full length 12 car Class 700?

 

[D365]

Forgive me if I’m missing something, where did this discussion of sending terminating 717s from Platform 5 to Platform 1 originate from?

 

[mr_jrt]

Have a look at the satellite imagery on google maps and consider the fact that there is the grade separation to overcome too (it's an diveunder by the way, not a flyover), and you'll see that the chord you suggest would not be cheap, assuming you mean it to be to the east of the mainline, which would be the only sensible place, to prevent occupation of the fast lines.

Sorry, muddled my words. Never suggested it would be cheap! Land looks pretty clear though, so it's eminently doable if desired.

And to what end? Since the Hitchin flyover was built there's a perfectly good place for any mainline trains to crossover and return (Letchworth) which doesn't block the main lines and serves two additional major communities. There's really no need for anything more than the scheme which is currently in progress. It's a "solution" to a problem which doesn't exist.

The whole reason the bay is needed (and Hertford loop services haven't been reaching Stevenage for quite some time) is that there is a capacity bottleneck between Stevenage and the Hitchin flyover due to increased ECML services. Sending services north just to reverse using the flyover would cause all sorts of problems, otherwise we wouldn't have the bay at all and services would continue to terminate at Letchworth as they used to. That said, we're just musing about turning ECML services at Stevenage here. I can't imagine there would be any major need to do so on a regular basis given the demand further north, so it's all just a bit of a mental exercise to spur some debate.

Also that new chord wouldn’t help at all as you still have to cross the Down and Up fast lines.

No you wouldn't? You would run bidi back toward Hertford under the ECML's four lines, then branch off south to join the ECML's up slow.

A easier solution would be to just reverse at Langley Junction and run bi directional into Plat 1 but that is cost that is not acceptable to bean counters so I suggest that anything terminating at Stevenage using Plat 4/5 just has to head back to London via Hertford.

In fairness, I did suggest that as well, but the two options would be either that signalling or the chord, and I suspect the chord would offer the better solution.

Realistically, obviously neither are needed now, but it's interesting to think about what may happen one day.

 

[Hadders]

As I understand it the reason the loop services no longer to to Letchworth is because there is insufficient track capacity north of Stevenage on the slows since the introduction of the enhanced Thameslink timetable.

This is the key reason why the bay platform at Stevenage is needed. Historically trains from the loop terminated in platform 4 and reversed but the introduction of the additional 2 trains an hour to Cambridge means there’s not time for the Hertford loop trains to use platform 4.

 

[Ianno87]

I suppose you could potentially have a South bound train in both of platform (4&5) during engineering work - say if the mainline is closed north of Stevenage. But that all depends on a specific set of circumstances, really, since you'll get different plans for different works.

If there's a failed train in 5, or the points into it have failed, Platform 4 remains available as a contingency.

As I understand it the reason the loop services no longer to to Letchworth is because there is insufficient track capacity north of Stevenage on the slows since the introduction of the enhanced Thameslink timetable.

This is the key reason why the bay platform at Stevenage is needed. Historically trains from the loop terminated in platform 4 and reversed but the introduction of the additional 2 trains an hour to Cambridge means there’s not time for the Hertford loop trains to use platform 4.

Needed to:
-Introduce the 2tph Brighton-Cambridge and operate the Hertford Loop to Stevenage (presently its either one or the other)
-Also saves a unit (thus ongoing cost) compared to running to Letchworth and back (that was seeving no real demand need anyway)
-Operationally segregates the Hertford Loop, with performance benefits

 

[Aictos]

No you wouldn't? You would run bidi back toward Hertford under the ECML's four lines, then branch off south to join the ECML's up slow.

Ain't possible because you can't get to the Up Slow from Langley Junction once you've used the dive under to access the Hertford Loop for the simple reason that the track isn't set up to allow that plus you've got that OHL equipment sub station in the middle of the triangle which is set up for trains from the Down/Up Slow to Hertford or the Down Hertford to the Down Slow.

The only way any train could access the Up Slow would to be reverse past Langley Junction then run wrong line to reverse behind K656 to then gain the Up Slow, that takes time as it's two reversals.

Simply isn't going to happen unless by some miracle, a flyover is put in to allow access from the Down to the Up but that isn't going to happen in my lifetime.

 

[Aictos]

If there's a failed train in 5, or the points into it have failed, Platform 4 remains available as a contingency.



Needed to:
-Introduce the 2tph Brighton-Cambridge and operate the Hertford Loop to Stevenage (presently its either one or the other)
-Also saves a unit (thus ongoing cost) compared to running to Letchworth and back (that was seeving no real demand need anyway)
-Operationally segregates the Hertford Loop, with performance benefits

You could do that at the moment in any case by running the Hertford/Gordon Hills over the Up/Down Slow 2's between Alexandra Palace and Finsbury Park but it's not being done.

Doing that would mean the Hertford Loop services would not be affected at all by ECML issues apart from Finsbury Park to Moorgate.

 

[mr_jrt]

Ain't possible because you can't get to the Up Slow from Langley Junction once you've used the dive under to access the Hertford Loop for the simple reason that the track isn't set up to allow that plus you've got that OHL equipment sub station in the middle of the triangle which is set up for trains from the Down/Up Slow to Hertford or the Down Hertford to the Down Slow.

The only way any train could access the Up Slow would to be reverse past Langley Junction then run wrong line to reverse behind K656 to then gain the Up Slow, that takes time as it's two reversals.

Simply isn't going to happen unless by some miracle, a flyover is put in to allow access from the Down to the Up but that isn't going to happen in my lifetime.

...I think you may have misunderstood me. I'm musing new infrastructure - a set of points immediately east of the ECML on the bidi down Hertford line, curving south and immediately rising up to level with the ECML's up slow, joining it as soon as it can, gradient permitting. I think there's plenty of room past the substation, personally. Nobody's seriously suggesting this, btw - just musing how to get more use out of the shiny new platform 5. *shrugs*

 

[Aictos]

...I think you may have misunderstood me. I'm musing new infrastructure - a set of points immediately east of the ECML on the bidi down Hertford line, curving south and immediately rising up to level with the ECML's up slow, joining it as soon as it can, gradient permitting. I think there's plenty of room past the substation, personally. Nobody's seriously suggesting this, btw - just musing how to get more use out of the shiny new platform 5. *shrugs*

And I think you haven't a clue on the actual layout there which makes it a non starter - for one thing any route would make the tight curve at St Pancras seem like nothing.

The best way to get more use out of Platform 5 is to simply to add a set of pointwork at the north end to join the Down Slow and convert the turnback into a loop thus allowing non stop services to bypass a stopping service using Platform 4.

Equally if Platform 5 was extended to 12 cars, while a Cambridge or a Peterborough is looped in Platform 5 you could have a freight carry on though Platform 4.

Obviously not all the time but it might help pathing to allow Platform 4/5 to be used for services to overtake a service stopped at Stevenage.