Bow Junction, why does it need to be modified?

[delticdave]

A silly question perhaps, an article in the March Modern Railways states that it needs to be changed to allow 30 tph (from current 22 tph) to / from Liverpool Street, but doesn't explain why.

AFAIK, the spur to Gas Factory Junction can't be a real problem 'cos it only has a passenger service at weekends, the new junction to Crossrail is located further towards Stratford.

Maybe the ECS moves to & from Orient Way are the reason?

DC

 

[swt_passenger]

A silly question perhaps, an article in the March Modern Railways states that it needs to be changed to allow 30 tph (from current 22 tph) to / from Liverpool Street, but doesn't explain why.

AFAIK, the spur to Gas Factory Junction can't be a real problem 'cos it only has a passenger service at weekends, the new junction to Crossrail is located further towards Stratford.

Maybe the ECS moves to & from Orient Way are the reason?

DC

Yes, it is all about better parallel routes from the fast lines into the platforms freed up by Crossrail, and allowing the ability to “bounce back” empty peak arrivals to Orient Way via a dedicated line. So in the morning peak there’d be capacity for more arrivals than departures as counted through Stratford, with 12 of the trains passing through P9 to the up electric (slow) line, and 16 though P10 to the up main.

Originally the London and SE route study a few years ago explained it all, with a track diagram, I think it’s come up in a more recent thread, and probably revised in detail in later studies. However it’s probably just as easy to link to the 2011 explanation. It is option D2, page 125 in this:
http://www.sydenhamsociety.com/wp-c...nd-south-east-route-utilisation-strategy1.pdf

 

[colchesterken]

If they are re-doing the junction could they do something to increase the speed limit.?
Out of Paddington and other main line stations 100 is the speed in a couple of miles out of the station
on G E the speed does not get up to even 90 till after Maryland and 100 till after Shenfield aprox 20 miles out

 

[306024]

Since then Greater Anglia have ordered new rolling stock that won’t fit in platforms 16 and 17 at Liverpool St, even after they have been lengthened to 205m, unless they are restricted to a five car formation (or a Stadler bi-mode combo). Platforms 16 and 17 can only be accessed from the electric lines at the throat. A five car in the morning peak is not advisable, and there won’t be that many bi-modes available to wander all the way up to London so the whole plan needs a bit of a rethink.

Increasing the line speed down to Stratford could require additional cant on the track, Bow Jn and Stratford are both on curves. Canted rails and lots of pointwork are not very compatible.

 

[delticdave]

Yes, it is all about better parallel routes from the fast lines into the platforms freed up by Crossrail, and allowing the ability to “bounce back” empty peak arrivals to Orient Way via a dedicated line. So in the morning peak there’d be capacity for more arrivals than departures as counted through Stratford, with 12 of the trains passing through P9 to the up electric (slow) line, and 16 though P10 to the up main.

Originally the London and SE route study a few years ago explained it all, with a track diagram, I think it’s come up in a more recent thread, and probably revised in detail in later studies. However it’s probably just as easy to link to the 2011 explanation. It is option D2, page 125 in this:
http://www.sydenhamsociety.com/wp-c...nd-south-east-route-utilisation-strategy1.pdf
View attachment 59610

Thanks for the information & the link, very interesting indeed.

DC

 

[swt_passenger]

Since then Greater Anglia have ordered new rolling stock that won’t fit in platforms 16 and 17 at Liverpool St, even after they have been lengthened to 205m, unless they are restricted to a five car formation (or a Stadler bi-mode combo). Platforms 16 and 17 can only be accessed from the electric lines at the throat. A five car in the morning peak is not advisable, and there won’t be that many bi-modes available to wander all the way up to London so the whole plan needs a bit of a rethink.
...

Isn’t the idea that P16 and P17 will be mainly used by the remaining Crossrail Liverpool St terminators in the peaks, which will arrive and depart on the electric lines anyway?

 

[306024]

That should only need one platform if the timings can work. Still leaves 15 and 16 going begging, for which the Bow Jn remodelling idea was originally envisaged. One of the main reasons for lengthening 16 and 17 is that should the tunnel be blocked for any reason at least passengers can get to Liverpool St, which is as far as many want to go anyway. Trying to terminate trains at Stratford would obviously not be practical in the morning peak in an emergency situation.

With the much higher passenger capacity of the new GA trains, the requirement to run more trains to meet demand is perhaps put back a few years.

 

[hwl]

Since then Greater Anglia have ordered new rolling stock that won’t fit in platforms 16 and 17 at Liverpool St, even after they have been lengthened to 205m, unless they are restricted to a five car formation (or a Stadler bi-mode combo). Platforms 16 and 17 can only be accessed from the electric lines at the throat. A five car in the morning peak is not advisable, and there won’t be that many bi-modes available to wander all the way up to London so the whole plan needs a bit of a rethink.

Increasing the line speed down to Stratford could require additional cant on the track, Bow Jn and Stratford are both on curves. Canted rails and lots of pointwork are not very compatible.

ASDO on the new stock should deal with the platform length issues what we don't know is the precise location of the new points in the throat as regards junction blocking.

 

[306024]

ASDO won't get you behind the signal at Liverpool St to go back again. The pointwork will be right on the end of the platform. Platform 18 has to be sacrificed because there is so little room.

 

[47421]

If they are re-doing the junction could they do something to increase the speed limit.?
Out of Paddington and other main line stations 100 is the speed in a couple of miles out of the station
on G E the speed does not get up to even 90 till after Maryland and 100 till after Shenfield aprox 20 miles out

come to WestAnglia where you can *never* get up to 100, in fact you can go to Whittlesford way and only go over 80 for about 10 seconds north of Brox before the anchors come in for the 55 through Roydon