Trowse swing bridge - maximum capacity?

Bald Rick · 19 Mar 2019

edwin_m said:
Was the second one checked by signals on the approach?

I think what happened is that the London was given the road from the platform to the signals protecting the bridge (CO564/566), ie a single yellow. Just as station duties were being completed and it was RA’d, the inbound EMT cleared the bridge, and the platform starter cleared to green. The driver thus went out at full tick (it was a beautiful day), and less than 2 mins later was on the bridge. It is, after all, only about half a mile from the platform ends at Thorpe to the bridge.

Adrian1980uk said:
Yes I was 6 / 7 when it was done so don't remember much... although crown point had an open day in 87 I think which my parents took me to.

We have to remember that was during the decline of the railways so it probably made sense to build single track. In those days too the solution to more capacity was generally another coach on the train rather than extra trains

There was a great article in Modern Railways at the time; back then there were basically 2 trains an hour each way over it with an occasional extra. Much later in his career I worked with the chap who built it, retired now of course.

I was at that open day too, first time I’d got myself across London on my own (I would have been about 14/15). The train down was pretty full, and full of anoraks - I’d never seen them in such numbers before, including one chap who was using a dictaphone to record numbers, and he almost expired with breathlessness as we went past Ilford. Then on the way back I had to stand the whole way, and got a horrendous migraine.

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eastdyke · 19 Mar 2019

Crown Point open day 1987? Took the family.
Video on youtube (not mine).

dk1 · 20 Mar 2019

Trowse Bridge no longer requires to be swung. It was last done to remove that Cadets training ship that was moored opposite Thorpe Station in 2017 which transferred to a new home in Woodbridge. It was quite an operation in the early hours when Carrow Road Bridge was also raised for the first time in many moons. There are now no large vessels between it & Foundry Bridge in the city & there is no requirement for anything to pass through except pleasure craft.

eastdyke · 20 Mar 2019

dk1 said:
Trowse Bridge no longer requires to be swung. It was last done to remove that Cadets training ship that was moored opposite Thorpe Station in 2017 which transferred to a new home in Woodbridge. It was quite an operation in the early hours when Carrow Road Bridge was also raised for the first time in many moons. There are now no large vessels between it & Foundry Bridge in the city & there is no requirement for anything to pass through except pleasure craft.

And I thought that Navigation Rights were (even) more zealously guarded than Rights to do just about anything else?
The Navigation body is the Broads Authority and this is what they say on their website:

Trowse Bridge currently is currently experiencing mechanical problems requiring extra assistance to operate. Network Rail therefore require seven days’ notice to open the bridge. The opening times are 9.05 am on Sundays and any day between 02.00 am and 04.00 am. To arrange opening please call Network Rail on either 01603 675297 or 01603 763440. Any problems in arranging the opening of the bridge should be reported to the Broads Authority Monitoring Officer on 01603 756018 or to [email protected], who will be pleased to assist.

http://www.broads-authority.gov.uk/boating/navigating-the-broads/bridge-heights-and-opening-times

chubs · 20 Mar 2019

dk1 said:
Trowse Bridge no longer requires to be swung. It was last done to remove that Cadets training ship that was moored opposite Thorpe Station in 2017 which transferred to a new home in Woodbridge. It was quite an operation in the early hours when Carrow Road Bridge was also raised for the first time in many moons. There are now no large vessels between it & Foundry Bridge in the city & there is no requirement for anything to pass through except pleasure craft.

Trowse bridge has been broken for ages hasn't it? I read somewhere that Carrow Bridge was being refurbished too as it's in pretty poor condition.

I've never seen either of the two footbridges on riverside open either. Presumably they must have to let the cadets old boat out. I wonder if the derelict floating restaurant may follow.

dk1 · 20 Mar 2019

The jacks at Trowse Bridge where damaged shortly after installation in 1986 & its always been a headache. A team have usually been required to be present on the occasions it has swung 'just in case'. At one time rails where welded at each end as Railtrack/Network Rail found it far far cheaper to pay river fines than it was shelling out in compensation to Train Operators. Thankfully now there is no need to swing it & any future double tracked Bridge will be a fixed structure.

dk1 · 20 Mar 2019

chubs said:
Trowse bridge has been broken for ages hasn't it? I read somewhere that Carrow Bridge was being refurbished too as it's in pretty poor condition.

I've never seen either of the two footbridges on riverside open either. Presumably they must have to let the cadets old boat out. I wonder if the derelict floating restaurant may follow.

I think that grotty old 'junk boat' excuse for a restaurant will end up sinking or simply floating away. Yes to think of all that money spent on the two footbridges with capacity to swing/lift & only ever used a handful of times. Worse still the Novi Sad one nearest the football ground has just been closed for £250k of repairs & was only built in 2001.

HLE · 20 Mar 2019

dk1 said:
I think that grotty old 'junk boat' excuse for a restaurant will end up sinking or simply floating away. Yes to think of all that money spent on the two footbridges with capacity to swing/lift & only ever used a handful of times. Worse still the Novi Sad one nearest the football ground has just been closed for £250k of repairs & was only built in 2001.

Repairs? It's a footbridge! Shocked that's needed so soon.

dk1 · 20 Mar 2019

HLE said:
Repairs? It's a footbridge! Shocked that's needed so soon.

Aren't we all :lol:

chubs · 20 Mar 2019

The upkeep is poor.

When it opened it had little lights along the floor on both ends and I think some lights shining on it too. They seem to have tarmacked over the lights!

MarkyT · 21 Mar 2019

edwin_m said:
I've never really understood the cost saving claimed for single lead junctions, at least where there is room for a "ladder" junction without a diamond. Both have four sets of points so it seems to me the only saving is a hundred metres or so of plain line. And junctions are precisely where most capacity is needed, which usually happens when trains to and from the same route are timetabled to pass each other on the junction.

At some constrained sites, a single lead might allow a longer junction with higher turnout speeds than might be achieved with a double ladder or diamond. And don't forget that PW and S&T engineers abhor switched diamonds and try to avoid having them if at all possible.

edwin_m said:
Pretty sure it's been like that since the re-signalling in the 70s. It was relaied a few years back but I think that was like for like.

Thus avoiding interlocking and panel alterations for Golborne.

dk1 · 21 Mar 2019

If running in a little early with the xx:00 from Liverpool St & the xx:40 Norwich-Cambridge has departed a couple of minutes down (as is often the case at the moment) it can just clear the bridge as I roll up towards the Red that clears as soon as the local is off the track circuit. Whack open the power & I can be on the swing bridge around 90seconds after the previous train has.

Richard Ingram · 21 Mar 2019

MarkyT said:
At some constrained sites, a single lead might allow a longer junction with higher turnout speeds than might be achieved with a double ladder or diamond. And don't forget that PW and S&T engineers abhor switched diamonds and try to avoid having them if at all possible.

I believe they are also useful if the branch is rarely used, as one of the turnouts is not traversed constantly and thus requires less maintenance.

Bald Rick · 21 Mar 2019

MarkyT said:
At some constrained sites, a single lead might allow a longer junction with higher turnout speeds than might be achieved with a double ladder or diamond. And don't forget that PW and S&T engineers abhor switched diamonds and try to avoid having them if at all possible.

That’s exactly it. There are plenty of sites where a double ladder junction won’t fit, but a single lead junction does. Ely North Junction used to be horribly slow when it was all double, and the only way to speed it up without buying land was to make most of it single lead junctions. There is an argument that it has actually increased capacity, as the junction margins reduced considerably, particularly for long freight trains.

edwin_m · 21 Mar 2019

I'm not a track engineer, but there also seem to be plenty of places where a single lead was used somewhere with plenty of space for a double ladder, and indeed some of them have been so converted since. It just seemed to be the default choice for certain parts of BR in the 70s, particularly in Scotland.

MarkyT · 21 Mar 2019

edwin_m said:
I'm not a track engineer, but there also seem to be plenty of places where a single lead was used somewhere with plenty of space for a double ladder, and indeed some of them have been so converted since. It just seemed to be the default choice for certain parts of BR in the 70s, particularly in Scotland.

Compared to a traditional double junction with diamond, a single lead gives quite comprehensive (but not full) inbuilt facing crossover connectivity between tracks, signalled or otherwise, for emergency use, scheduled turnbacks, access to other siding turnouts around the junction etc. A double ladder gives some of that connectivity but less than a single lead. In the single lead, clearly it's paid for by reduced parallelism and more potential head-on conflicts without possibility of flank protection. TPWS or other future train protection should be able to manage that risk adequately today, but performance demands of today's busy railway often demands more parallism, even sometimes to the extent of sacrificing speed for resilience. The best value and most reliable junction is often the traditional double with fixed diamond as this only has TWO mechanised turnouts to purchase, maintain and fail compared to the double ladder's, switched diamond double's, and single lead's FOUR, but in many particular junctions' geometries these can severely limit turnout speed, as the crossing angle must be sufficiently large for the fixed diamond. In terminal throats for example, fixed diamonds are often perfectly acceptable as low 'blanket' speeds often apply. The same might apply if the junction turnout is followed immediately by an unavoidable tight curve or other feature that itself limits speed anyway, or a station that the majority of trains stop at.
http://www.townend.me/files/Junctions.pdf

Class 170101 · 21 Mar 2019

Bald Rick said:
That’s exactly it. There are plenty of sites where a double ladder junction won’t fit, but a single lead junction does. Ely North Junction used to be horribly slow when it was all double, and the only way to speed it up without buying land was to make most of it single lead junctions. There is an argument that it has actually increased capacity, as the junction margins reduced considerably, particularly for long freight trains.

But that junction is either still double Blocked or still required to be planned that way even with TPWS so not sure whether it has increased capacity or not. It must be pretty close to being full consulting RTT and that doesn't take Queen Adelaide Level Crossing into account.

Bald Rick · 21 Mar 2019

Class 170101 said:
But that junction is either still double Blocked or still required to be planned that way even with TPWS so not sure whether it has increased capacity or not. It must be pretty close to being full consulting RTT and that doesn't take Queen Adelaide Level Crossing into account.

My memory fails me, but from my time in Cambridge ‘box it’s only double blocked from Peterborough to Ely, and not any of the other routes.

dk1 · 21 Mar 2019

Bald Rick said:
My memory fails me, but from my time in Cambridge ‘box it’s only double blocked from Peterborough to Ely, and not any of the other routes.

It's double blocked from Ely to Kings Lynn & Norwich. TPWS apparently would have been too complicated to mitigate everything. Only moves that changed where from Peterborough at Ely West Jcn allowing trains in the up direction to go via the down & for the West Curve to become bidi.

Class 170101 · 21 Mar 2019

dk1 said:
It's double blocked from Ely to Kings Lynn & Norwich. TPWS apparently would have been too complicated to mitigate everything.

Interesting. Would be interesting to know how the old layout would work now under modern signalling regulations.

Only moves that changed where from Peterborough at Ely West Jcn allowing trains in the up direction to go via the down & for the West Curve to become bidi.

Not that the Bi-Directional operating from Ely West Jn to Ely since re-commissioing is used all that much. Something like 3 EMT services daily Monday to Saturday at most as far as I can tell and they aren't easy to find as I don't think they are shown any differently in scheduling systems. (unless someone knows differently)

dk1 · 21 Mar 2019

Class 170101 said:
Interesting. Would be interesting to know how the old layout would work now under modern signalling regulations.

Not that the Bi-Directional operating from Ely West Jn to Ely since re-commissioing is used all that much. Something like 3 EMT services daily Monday to Saturday at most as far as I can tell and they aren't easy to find as I don't think they are shown any differently in scheduling systems. (unless someone knows differently)

It does happen ad-hoc too as you can imagine with such a complex nature of services/routes. Came in recently side by side with a XC170.

stonojnr · 17 Apr 2019

Trowse is single track because it needed to operate as a swing bridge as the rivers/broads authority have access rights,and I believe nobody in the UK had any experience of building a swingbridge which also carried catenary wires for electric trains at that time, and swing bridges are pretty complicated beasts at the best of times trying to get the rails re-aligned, let alone some kind of dual track electrified section going too. So it in the end was made single track because that was the simplest solution for a swing bridge setup, I think they literally use a lump of metal strong enough to cope with pantographs hitting it and all the movements the bridge was expected to have to carry out, and thats also why the speed is restricted through it.

as it happened yes, they managed to damage the movement motion of the bridge, which shows how tricky swing bridges are, which meant it was effectively shut for most of the past 30 years and when it needed to open, they always had a crane to lift it and lots of people on site in case it got stuck open, which would be incredibly awkward for all concerned.

its a recognised bottleneck to the station as all the Brandon/Ely/Cambridge direction trains use it as well as the London trains. But the cost estimate is north of 100million plus however long it puts the station/Crown point effectively out of service to do it, so Network Rail arent in a hurry to spend money on it as it "works" for them, and frankly if they were fixing bridges in that area, Reedham swing bridge, which still works and opens multiple times per day in the summer season,but doesnt carry electricity, is slowly rusting away into the River Yare at a more problematic rate

Rick1984 · 26 May 2019

Anyone have a picture of Lady Julian Bridge at The Riverside open? Can't find one on Google

chubs · 27 May 2019

Rick1984 said:
Anyone have a picture of Lady Julian Bridge at The Riverside open? Can't find one on Google

I've looked before and not found one, or any of the novi sad friendship bridge opening. Spend all that money on operable bridges that never open...

Meerkat · 27 May 2019

stonojnr said:
But the cost estimate is north of 100million plus however long it puts the station/Crown point effectively out of service to do it

That much for a non-swinging bridge?!
Maybe needs a wider redevelopment with rail and road bridges to open up the land either side of the river by Crown Point....

Rick1984 · 27 May 2019

Could widening the existing bridge deck be an option. Or build the new bridge parallel to the old one to reduce time closed?

Meerkat · 27 May 2019

If closure period is a massive issue, and swinging is no longer required, maybe you could build a new single bridge (eventually to be the up line) then remove the old bridge and put in a new down bridge.
A complication looks to be a headshunt in the depot??

Bald Rick · 27 May 2019

Rick1984 said:
Could widening the existing bridge deck be an option. Or build the new bridge parallel to the old one to reduce time closed?

The bridge was built as single track because:

a) traffic did not warrant double track (and still doesn’t)
b) it had to be built alongside the old bridge whilst the latter was still open to traffic, and there was (and still is) only just enough space within railway land to get a single track bridge in.

You can’t build two swing bridges side by side too close to each other for obvious reasons.

lincolnshire · 27 May 2019

To put a fixed bridge in position will require an Act of Parliament to close the river to navigation as they had a temporary closure via an Act of Parliament when they installed the present bridge. I always remember someone saying that the contractors never took away there site huts as they was always back on site trying to make it work properly.

Meerkat · 27 May 2019

An Act of Parliament wouldn’t be that tricky unless there are local boating extremists?

Trowse swing bridge - maximum capacity?

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