Werrington and Glinton Jn Type

[Legolash2o]

I'm wondering why the new Glinton Jn in the Werrington area has the type of points that require the train to ever so slightly travel on the other track (red line) rather than more curved approach (green line)?

I thought green would be cheaper and would require less moving parts to main. one mechanical switch as opposed to three. Although there could be a small bi-directional working for reversals on the line the train is currently on.

 

[swt_passenger]

The double junction with three (four altogether) sets of points is the preferred choice nowadays, as long as there is room (ie overall length), because it removes the ‘diamond’ crossing which is a long term maintenance issue because of the wear it gets.

(It can also give you a crossover and reversing facility in some locations depending on the overall signalling available.)

 

[Legolash2o]

Thanks for the reply and info!

Is there a good document/website to look up different types of junctions please?

 

[Watershed]

I'm wondering why the new Glinton Jn in the Werrington area has the type of points that require the train to ever so slightly travel on the other track (red line) rather than more curved approach (green line)?

I thought green would be cheaper and would require less moving parts to main. one mechanical switch as opposed to three. Although there could be a small bi-directional working for reversals on the line the train is currently on.

View attachment 105655

You're alluding to the difference between a diamond crossing (green annotation) and a ladder crossing (red annotation).

For a diamond crossing to avoid having mechanical switches/points ("fixed diamond"), the angle of the crossing can be no flatter than 1 in 8. This inherently restricts the speed of the diverging line - typically to no more than 30mph or so (though this depends on the width of the six-foot).

Therefore a turnout that's any faster will require either a ladder crossing or a switched diamond - where, as shown in this picture

you end up with the same number of moving parts as a ladder crossing.

A switched diamond is much more labour intensive and hence expensive to maintain than a ladder crossing, and has to be custom built for each junction. This means it can take a long time to replace something like a cracked crossing nose, whereas a ladder crossing which will often contain "off the shelf" components that are more quickly replaced.

The ride over a ladder crossing is obviously less comfortable than that over a diamond crossing, but the lower maintenance costs and additional signalling flexibility which you gain through a ladder crossing mean that diamond crossings are definitely the non-preferred option. In newly designed layouts, they will now typically only be used where space or other considerations mean that a ladder crossing is impracticable.

 

[swt_passenger]

The weave looks far worse than it really is of course because the photo compresses distance so much.

I found a quick discussion we had back in 2014 that, (despite its title), went on to discuss the pros and cons of a ladder type junction. You sometimes see it referred to as a “simplified double junction” by NR - which seems odd because at first glance it looks much more complicated. As @Watershed mentioned, if there’s a switch diamond involved that’s effectively a couple more sets of points anyway, but I think they’re sometimes present without being noticed?

Single lead Junctions

travelling down from Fort William today, I noticed at westerton Junction we were travelling wrong line for quite some distance until we diverged towards cowlairs. I am surprised at how long this lead is on a busy suburban line. Is this at all exceptional in the UK, especially with the safety...

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[Roast Veg]

Therefore a turnout that's any faster will require either a ladder crossing or a switched diamond - where, as shown in this picture
View attachment 105658
you end up with the same number of moving parts as a ladder crossing.

I'm assuming Colwich is an example of a switched diamond?

 

[InOban]

As a matter of interest, when it's finally in use - and it seems to me that all they've done since the signalling finished in September is titivating it and clearing the site - why is the original down line being retained ? All trains which currently use it will use the dive under,

 

[GB]

All trains which currently use it will use the dive under,

Where have to read that?

 

[Legolash2o]

Thanks everyone.

As a matter of interest, when it's finally in use - and it seems to me that all they've done since the signalling finished in September is titivating it and clearing the site - why is the original down line being retained ? All trains which currently use it will use the dive under,

I suspect it may be used primarily by passenger services.

 

[zwk500]

Thanks everyone.


I suspect it may be used primarily by passenger services.

The original will also be used by freight in the event of line blockages, or for freight to/from the ECML (although down freight may still cross the stamford lines rather than the ECML fasts.

 

[TheBigD]

As a matter of interest, when it's finally in use - and it seems to me that all they've done since the signalling finished in September is titivating it and clearing the site - why is the original down line being retained ? All trains which currently use it will use the dive under,

The local EMR service to/from the Spalding line will continue to use the existing route, as will any liners to/from London Gateway. The liners to/from Felixstowe and stuff to/from Anglia like the Middleton Towers sand trains will use the dive under, and the dive under also allows for a trains to be held there if needed.

 

[GB]

The liners to/from Felixstowe and stuff to/from Anglia like the Middleton Towers sand trains will use the dive under,

Unless they need to access Peterborough V.Q

 

[Crun]

Unless they need to access Peterborough V.Q

V.Q?

 

[GB]

Sorry, Virtual Quarry.

 

[Watershed]

V.Q?

Virtual Quarry.

 

[InOban]

I had thought that since the purpose of the diveunder was to free up paths on the ECML, that they would be keen to get any Gateway freight on to the slows as soon as possible, ie in Peterborough, rather than blocking the up fast as it crawls slowly across the flat junction.

 

[Starmill]

You're alluding to the difference between a diamond crossing (green annotation) and a ladder crossing (red annotation).

For a diamond crossing to avoid having mechanical switches/points ("fixed diamond"), the angle of the crossing can be no flatter than 1 in 8. This inherently restricts the speed of the diverging line - typically to no more than 30mph or so (though this depends on the width of the six-foot).

Therefore a turnout that's any faster will require either a ladder crossing or a switched diamond - where, as shown in this picture
View attachment 105658
you end up with the same number of moving parts as a ladder crossing.

A switched diamond is much more labour intensive and hence expensive to maintain than a ladder crossing, and has to be custom built for each junction. This means it can take a long time to replace something like a cracked crossing nose, whereas a ladder crossing which will often contain "off the shelf" components that are more quickly replaced.

The ride over a ladder crossing is obviously less comfortable than that over a diamond crossing, but the lower maintenance costs and additional signalling flexibility which you gain through a ladder crossing mean that diamond crossings are definitely the non-preferred option. In newly designed layouts, they will now typically only be used where space or other considerations mean that a ladder crossing is impracticable.

The picture looks awfully familiar. It looks like it has been taken from the bridge that carries the footpath of Minsthorpe Lan, the road at Moorthorpe station.

 

[waverley47]

We should see most down freight destined for the joint line using the diveunder, either crossing from the down fast ECML onto the down Stamford, and thence underneath, or from the Ely lines.

Up traffic is more varied, with ECML destined freight (Dollands Moor or Gateway primarily) using the ECML up reversible, and Ely bound freight using the diveunder.

Of course, anything needing the yards on the up side of the ECML may still need to cross, but this has reduced considerably in recent years after NR control requested that driver changes take place at Peterborough station instead. Most movements into the yards are either bulk flows of ballast to the VQ, loco trips to Whitemoor, or freight being recessed overnight.

 

[Watershed]

The picture looks awfully familiar. It looks like it has been taken from the bridge that carries the footpath of Minsthorpe Lan, the road at Moorthorpe station.

It would appear so.

 

[TheBigD]

I had thought that since the purpose of the diveunder was to free up paths on the ECML, that they would be keen to get any Gateway freight on to the slows as soon as possible, ie in Peterborough, rather than blocking the up fast as it crawls slowly across the flat junction.

Depends. There's a number of options. Crossing over to up slow* at Spital Junction just north of Peterborough station is 15mph, crossing over at Werrington Junction is 40mph. They could also cross on to the Down Stamford at New England Junction and access the dive under from there. There's a couple more options too.

* Up slow is bi directional between Peterborough and Werrington and allows the Spalding trains to run in and out of Peterborough without crossing the ECML fast lines.

 

[fgwrich]

The double junction with three (four altogether) sets of points is the preferred choice nowadays, as long as there is room (ie overall length), because it removes the ‘diamond’ crossing which is a long term maintenance issue because of the wear it gets.

(It can also give you a crossover and reversing facility in some locations depending on the overall signalling available.)

After Network Rail's experience with the ever troublesome Diamond Crossing in Basingstoke (Up main / Down Reading), I'm not surprised why they favour using double junctions. I believe they would like to do away with that one at some point in the future given it's near permanent speed restriction these days.

 

[Crun]

Trains on the ECML around Werrington Junction in mid-November 2021. A YouTube film by werrington junction:

 

[adamedwards]

Are the new lines through the diveunder reversible? The line to Spalding appears to be signalled as such (judging from a vist last weekend) so it would be logical for reversible working to continue into Peterborough station.

 

[Shwam3]

Are the new lines through the diveunder reversible? The line to Spalding appears to be signalled as such (judging from a vist last weekend) so it would be logical for reversible working to continue into Peterborough station.

No, both lines are unidirectional.

 

[adamedwards]

Thank you for that. Sadly no news today from the govt of money of my pet project to extend Thameslink to a Peterborough North via the new tunnel. I'll keep my hopes up for 2060.

 

[Boodiggy]

I'm assuming Colwich is an example of a switched diamond?

Happy to be corrected by I think Colwich is a fixed diamond - obtuse crossings.

 

[Watershed]

Happy to be corrected by I think Colwich is a fixed diamond - obtuse crossings.

The geometry helps; the trackbed is very wide on the approach to the junction so the angle is rather sharper than it might otherwise be. The line to Stone is 45mph, though that's arguably more as a result of the curve radius.

 

[Crun]

As a matter of interest, when it's finally in use - and it seems to me that all they've done since the signalling finished in September is titivating it and clearing the site - why is the original down line being retained ? All trains which currently use it will use the dive under,

Dear Christopher,

Thank you for contacting us to request information on the opening of Werrington junction dive under.

Werrington junction dive-under is due to open to freight traffic in December.

There will be a ministerial visit when the dive under opens, this will not be accessible to members of the public.

I hope that you find this information helpful.

Kind Regards
Sharon Neil
Network Rail

 

[Mag_seven]

As the question that the OP placed in the opening post has been answered we will bring this thread to an end at this point.

For discussion of Werrington grade separation updates please use this thread:

Werrington grade separation updates

I thought there was a thread about the recent announcement that unspecified improvements to the ECML would go ahead, but I can't find it, so I'll start a new one for this item. The T&W Act Order for Werrington grade separation north of Peterborough has been approved...

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