How does the OHLE work on the Norwich swing bridge?

[alex17595]

Question is in the title.
I was going through Norwich and was wondering how it came apart when the bridge opens (if it does anymore).

Thanks in advance.

 

[MarkyT]

Question is in the title.
I was going through Norwich and was wondering how it came apart when the bridge opens (if it does anymore).

The overhead conductor wire is substituted by a fixed rail system over Trowse swing bridge itself and wires are terminated either side. I don't believe it's actually used very much at all now for water traffic, but has to remain serviceable and is presumably tested periodically.

 

[w0033944]

Question is in the title.
I was going through Norwich and was wondering how it came apart when the bridge opens (if it does anymore).

Thanks in advance.

Through Norwich? Clever that, given that it's a terminus (I suppose you might have entered on one line and left on another).

 

[snowball]

If Selby to Hull electrification gets the go-ahead, there'll be a similar but double-track example at Selby.

 

[alex17595]

Through Norwich? Clever that, given that it's a terminus (I suppose you might have entered on one line and left on another).

I have been through Norwich a few times today. Gone out/in the east side three times and over the bridge four times!

 

[w0033944]

I have been through Norwich a few times today. Gone out/in the east side three times and over the bridge four times!

Which line(s) did you go on?

 

[John Webb]

They say a picture is worth a thousand words:
National Express East Anglia train crossing Trowse swing bridge

© Copyright Evelyn Simak and licensed for reuse under this Creative Commons Licence.
(Click on photo to go to the larger original - there are a few others of the bridge and the OHLE at the same GeoGraph page.)

 

[table38]

In Holland, they don't always bother with the wires

[youtube]JLKAUIGXnLY[/youtube]

 

[TheGrew]

Would the Dutch approach work in the UK? I would have thought the pantograph would fully extend and the pull down the wires on the other side (or rip off the pantograph)

Sent from my Nexus 4 using Tapatalk

 

[alex17595]

Which line(s) did you go on?

Basically my day went:

Burton on Trent to Norwich
Norwich to Ipswich
Ipswich to Lowestoft
Lowestoft to Norwich
Norwich to Great Yarmouth
Great Yarmouth to Norwich (Via Berney Arms)
Norwich to Diss
Diss to Norwich
Norwich to Burton (Via London)

Would the Dutch approach work in the UK? I would have thought the pantograph would fully extend and the pull down the wires on the other side (or rip off the pantograph)

Probably a bit of both.
They can extend pretty far:

 

[TheKnightWho]

If Selby to Hull electrification gets the go-ahead, there'll be a similar but double-track example at Selby.

If this is successful, could we see the Norwich one redoubled?

 

[snowball]

I think Trowse bridge was completely replaced when it was electrified and any double tracking would require replacing it again, so I would have thought not likely to happen.

Presumably the reason it's single track is because double track would have been more expensive and single was thought adequate for the traffic, rather than because of any supposed technical difficulties of an electrified double track bridge.

Presumably on that Dutch bridge the wire is close to the maximum height to which the pantograph can stretch, and for the final approach the wire becomes a rigid rail, with an upward curve at the end. I doubt their pantographs are much different from ours.

 

[telstarbox]

What's the speed limit on the swing bridge?

 

[tom1681]

What's the speed limit on the swing bridge?

If you mean Trowse then it's 40mph - but with a 30mph shortly afterwards and then soon after that a 25mph on the approach to Norwich station it's not reached by anything except perhaps the third pantograph on the daily visit of a 321 when it's leaving Norwich.

 

[O L Leigh]

I think Trowse bridge was completely replaced when it was electrified and any double tracking would require replacing it again, so I would have thought not likely to happen.

Presumably the reason it's single track is because double track would have been more expensive and single was thought adequate for the traffic, rather than because of any supposed technical difficulties of an electrified double track bridge.

I believe it also has to do with the width of the bridge deck once swung into the open position for river traffic. A double-track bridge deck would probably be so wide to still be an obstruction whereas a single-track deck is sufficient. Admittedly I don't know how much river traffic there is now and how often the bridge needs to be opened, but it may be the case that the need for a swing bridge has passed.

Presumably on that Dutch bridge the wire is close to the maximum height to which the pantograph can stretch, and for the final approach the wire becomes a rigid rail, with an upward curve at the end. I doubt their pantographs are much different from ours.

Not really. I'm guessing that these Dutch units must have some sort of maximum height restriction beyond which the pantograph can not rise. British trains don't have this restriction and the pantograph would simply continue to rise until it either "breaks it's back" or, if fitted with Automatic Dropping Device (ADD), it goes over-height and vents out the air causing the pantograph to drop.

It's simpler to fit the only electrified swing bridge with a metal rail than it is to re-equip every electric train with a new pantograph.

O L Leigh

 

[tom1681]

I believe it also has to do with the width of the bridge deck once swung into the open position for river traffic. A double-track bridge deck would probably be so wide to still be an obstruction whereas a single-track deck is sufficient.

Although the original was double tracked... https://www.flickr.com/photos/hodgesprints/7178900178/ (not my image).

 

[w0033944]

Basically my day went:

Burton on Trent to Norwich
Norwich to Ipswich
Ipswich to Lowestoft
Lowestoft to Norwich
Norwich to Great Yarmouth
Great Yarmouth to Norwich (Via Berney Arms)
Norwich to Diss
Diss to Norwich
Norwich to Burton (Via London)

Pretty intense and thorough itinerary! Seems as though the only line you didn't use was the Bittern Line to Cromer and Sheringham. What was your impression of the trips?

 

[alex17595]

Pretty intense and thorough itinerary! Seems as though the only line you didn't use was the Bittern Line to Cromer and Sheringham. What was your impression of the trips?

I did the Bittern line on New years eve so I didn't bother.

I like how you can do Ipswich to Norwich via Lowestoft on 1 unit.