Castleton South Junction Renewal and M62 bridge replacement

[cin88]

It isn't rumour, it was completely shot. Those chunks that were missing were from concrete that had fell away rather than any strikes.

 

[roughyed]

If you go through the dates the Google car has been under you can see the concrete is getting progressively worse. I have lived near by all my life never heard of any bridge strikes, I think it was just genuinely ready to fall down.

Railway rumors' say it should've been replaced a decade ago, and on the last inspection it was basically a case of "if you don't do something now its coming down by itself!"

The damage on the demolished bridge was definitely caused by strikes, as I stated previously, probably by mobile cranes etc. I too studied the dates on Google and I suddenly realised that from the date the bridge was built approximately 1970 until about 2020, there was very little damage. About 2020 the motorway was converted to a SMART!!!!! motorway. The hard shoulder on the original motorways was under engineered because it only had to cope with the occasional broken down vehicle. When it was decided to have all lanes running, the hard shoulder had to be strengthened. Obviously during this process lane 1 had somehow ended up with less headroom, resulting in more strikes.
If the new bridge has a similar headroom then it to is vulnerable. Hopefully the Network Rail engineers have realised this and created more headroom.

 

[david l]

The bridge 'may' have been hit by the odd bridge strike, but it has suffered from what the layman would call 'concrete cancer' which is certainly the principal reason for its replacement. For some time there has been a 20 mph restriction on the bridge and a 1 train only regulated by the signalboxes on each side. Discussions regarding replacement have been going on for some time, with regular and increasing inspections concluding the somewhat obvious. Indeed the diamond crossing which is actually on the bridge was plain lined some time ago (without informing the users!) to reduce the hammer blow on the bridge from the full bio-mass trains which go that way.

 

[Flying Claret]

The damage on the demolished bridge was definitely caused by strikes, as I stated previously, probably by mobile cranes etc. I too studied the dates on Google and I suddenly realised that from the date the bridge was built approximately 1970 until about 2020, there was very little damage. About 2020 the motorway was converted to a SMART!!!!! motorway. The hard shoulder on the original motorways was under engineered because it only had to cope with the occasional broken down vehicle. When it was decided to have all lanes running, the hard shoulder had to be strengthened. Obviously during this process lane 1 had somehow ended up with less headroom, resulting in more strikes.
If the new bridge has a similar headroom then it to is vulnerable. Hopefully the Network Rail engineers have realised this and created more headroom.

You're suggesting the new lane 1 was higher than the rest of the lanes..? How would it end up with less headroom?

 

[swt_passenger]

You're suggesting the new lane 1 was higher than the rest of the lanes..? How would it end up with less headroom?

The drawing of the existing bridge in the planning application, (linked a while ago in post #33), does show a slightly lower clearance over the westbound lane 1 which would have originally been the hard shoulder. 5020 mm which is about 16ft 5⅝ in. But AFAICT still not enough to justify warning signs. I think it might be the normal sort of camber on the slight right hand curvature of the road.

 

[J s]

The bridge 'may' have been hit by the odd bridge strike, but it has suffered from what the layman would call 'concrete cancer' which is certainly the principal reason for its replacement. For some time there has been a 20 mph restriction on the bridge and a 1 train only regulated by the signalboxes on each side. Discussions regarding replacement have been going on for some time, with regular and increasing inspections concluding the somewhat obvious. Indeed the diamond crossing which is actually on the bridge was plain lined some time ago (without informing the users!) to reduce the hammer blow on the bridge from the full bio-mass trains which go that way.

I have no knowledge about this bridge in particular but ‘concrete cancer’ does sound like a very plausible explanation for the poor state of the bridge. You see this a lot in buildings which obviously don’t suffer from bridge strikes in the same way. ‘Concrete cancer’ is just a result carbonation of the concrete. This happens because carbon dioxide dissolves in rainwater which causes the rain to become very slightly acidic. Concrete in its virgin state protects the steel reinforcing bars (which are necessary for strength) from rusting because the concrete interior is alkaline. If the concrete is left exposed to the atmosphere, the slightly acidic rainwater reduces the alkalinity of the concrete very slowly over time, working inwards from the exposed surface. Over many years, when the depth of carbonation reaches the reinforcing bars, the slightly acidic composition of the concrete allows the steel to react with oxygen which causes the reinforcing bars to rust. Rust takes up more volume than steel, so the bars physically get bigger which causes bursting stresses in the concrete which will eventually spall (i.e lumps fall off). Good design practice today tells you to put the reinforcing bars deep enough into the concrete so that the carbonation will never reach the reinforcing bars. concrete carbonation wasn’t a well understood mechanic until relatively recently, so you see this effect a lot on older buildings and bridges from the 70s and earlier. I had a look on street view and you can see where they have marked locations where rusted bars have caused lumps of concrete to spall off. Quite a nice example actually. It wouldn’t surprise me if the exhaust from cars made this effect worse. Nitrogen oxide I think causes a stronger acid.

 

[roughyed]

The bridge 'may' have been hit by the odd bridge strike, but it has suffered from what the layman would call 'concrete cancer' which is certainly the principal reason for its replacement. For some time there has been a 20 mph restriction on the bridge and a 1 train only regulated by the signalboxes on each side. Discussions regarding replacement have been going on for some time, with regular and increasing inspections concluding the somewhat obvious. Indeed the diamond crossing which is actually on the bridge was plain lined some time ago (without informing the users!) to reduce the hammer blow on the bridge from the full bio-mass trains which go that way.

A couple of weeks ago, I was looking at the old bridge in a nostalgic kind of way to see just how bad it was, and it was seriously bad. I still maintain that it was damaged by several strikes as well as the obvious corrosion. The lower edge on the west side is undamaged and the other 2 edges on the east bound carriageway also are undamaged.
However it was the possibility that the new bridge could be struck was the main concern.
I contacted Network Rail and they have given me some figures. A survey of the old bridge prior to demolition showed a minimum headroom of 5.135m westbound above lane 1 it is now 5.402m. Apparently the modern standard is 5.300m. To quote them " This increase in headroom will significantly reduce the risk of bridge strikes in the future. However should a vehicle collide with the new structure both the deck and bearings have been designed to resist accidental vehicle impact loading such that there is no loss of structural performance."
Over and out.

 

[RikGarner]

Newbie question, what does plain-lining mean?

 

[Mcr Warrior]

Newbie question, what does plain-lining mean?

Usually means removing all the points, crossovers, junctions, etc., on a particular section of railway line.

 

[Ploughman]

And replacing with Plain length of rail, often replacing just some of the Baseplates and timbers. Especially if there is a possibility of more renewal work in the future.

 

[swt_passenger]

Found a video which includes the new bridge being transported into position. Surprised NR haven’t released a similar video yet.

 

[buz33]

Surprised NR haven’t released a similar video yet.

Here is the Network Rail press release from 25th Sept which includes a video.

Network Rail completes work to rebuild motorway bridge near Rochdale​

Rail passengers and motorists are being thanked for their patience during work to demolish and rebuild a bridge over the M62.


The railway between Manchester Victoria and Rochdale reopened this morning (25 September) following a 19-day closure, allowing Network Rail to complete the £22m essential upgrade.


In recent months, engineers excavated over 50,000 tonnes of earth to create a safe and bespoke worksite next to the busy motorway to assemble the new bridge. Two 42-metre, 70-tonne steel beams were fabricated in Ireland and travelled over 200 miles by land and sea to site.


Over two weekends in September, the M62 was closed, and the 100+ strong team worked around the clock to demolish the existing 2000-tonne bridge, then replaced the old structure with a brand-new, future-proofed bridge.


The new bridge is expected to last 120 years and will never need painting due to its weathering steel design.


Network Rail has unveiled timelapse footage of the project which shows the huge scale of work required.

 

[swt_passenger]

Here is the Network Rail press release from 25th Sept which includes a video.

Ah thanks, that wasn’t there when I last looked, I was searching for Network Rail in a YouTube search box, but there’s been a few ‘unofficial‘ versions including the same sequence.

 

[themiller]

I have no knowledge about this bridge in particular but ‘concrete cancer’ does sound like a very plausible explanation for the poor state of the bridge. You see this a lot in buildings which obviously don’t suffer from bridge strikes in the same way. ‘Concrete cancer’ is just a result carbonation of the concrete. This happens because carbon dioxide dissolves in rainwater which causes the rain to become very slightly acidic. Concrete in its virgin state protects the steel reinforcing bars (which are necessary for strength) from rusting because the concrete interior is alkaline. If the concrete is left exposed to the atmosphere, the slightly acidic rainwater reduces the alkalinity of the concrete very slowly over time, working inwards from the exposed surface. Over many years, when the depth of carbonation reaches the reinforcing bars, the slightly acidic composition of the concrete allows the steel to react with oxygen which causes the reinforcing bars to rust. Rust takes up more volume than steel, so the bars physically get bigger which causes bursting stresses in the concrete which will eventually spall (i.e lumps fall off). Good design practice today tells you to put the reinforcing bars deep enough into the concrete so that the carbonation will never reach the reinforcing bars. concrete carbonation wasn’t a well understood mechanic until relatively recently, so you see this effect a lot on older buildings and bridges from the 70s and earlier. I had a look on street view and you can see where they have marked locations where rusted bars have caused lumps of concrete to spall off. Quite a nice example actually. It wouldn’t surprise me if the exhaust from cars made this effect worse. Nitrogen oxide I think causes a stronger acid.

The rebar should have a minimum of 50mm of concrete cover to prevent this damage shown in the photo. It doesn’t look like ‘concrete cancer’ to me as there’s no sign of chemical damage, only mechanical damage. PIt can be repaired quite easily but the concrete has to be dug out until clean steel is exposed on all surfaces. The steel is then cleaned and coated with a special proprietary repair paste before being buried once more to the required depth by a special repair grout. Of course it would depend on the extent of damage, an assessment of further rebar bursting of the concrete and the life expectancy of the structure.

 

[J s]

Depth is dependent on exposure class and cement mix, but 50mm is probably a safe bet for most circumstances.

 

[Meerkat]

Why were there containers under the old bridge whilst they chewed it away?

 

[td97]

Are there any bright ideas why the 2 minute engineering allowance is still included post timetable change?

 

[The Planner]

Are there any bright ideas why the 2 minute engineering allowance is still included post timetable change?

Why would it go? Box time is a permanent fixture.

 

[td97]

Why would it go? Box time is a permanent fixture.

Sorry, misunderstanding then. I thought that allowance was included on account that only 1 train (in either direction) was permitted to cross the old bridge.

 

[jfollows]

Sorry, misunderstanding then. I thought that allowance was included on account that only 1 train (in either direction) was permitted to cross the old bridge.

That’d be pathing allowance, wouldn’t it, in the old days inside a circle in the WTT? More recently in round brackets such as (1). To denote additional time because of conflicting movements.
Engineering allowance became “box time” because it used to be shown in a rectangular box, although it’s now shown in square brackets such as [2].

 

[DynamicSpirit]

Now I'm intrigued. What's the difference between 'engineering allowance' and 'pathing allowance'?

 

[jfollows]

Now I'm intrigued. What's the difference between 'engineering allowance' and 'pathing allowance'?

I’m just a long-time reader of working timetables, I don’t work in the industry.

The former is a standard allowance added to the timetable in specific places to allow for delays caused by engineering such as speed restrictions over newly installed tracks. It can vary by time of day but is generally the same for all trains and makes up a similar total of minutes for all trains over a route, such as Manchester to London. If the train suffers this amount of delay it will still arrive on time.

The latter is because of conflicts, delaying one train because otherwise it’d be at the same place at the same time as another, and clearly the signalling wouldn’t allow this. It’s specific to one train path only.

== Doublepost prevention - post automatically merged: 18 Dec 2024 ==

The “official” description may use slightly different words from mine.

 

[zwk500]

Now I'm intrigued. What's the difference between 'engineering allowance' and 'pathing allowance'?

Engineering allowance is specified in the Rules and is agreed with operators to account for time specifically in the realm of engineering (primarily ESRs/TSRs but you also get Engineering allowance for single-line working or when 4-track railways are reduced to 2-track).
Pathing allowance is time inserted into the schedules by planners (TOC or NR) to maintain the necessary margins and headways between trains required in the rules.
You also have performance allowance (in diamond brackets <>) which is to allow for general delay recovery approaching sensitive areas, and adjustment allowance (in curly brackets {}) which is strictly for modifying the runtimes due to a lower speed route (exceptionally negative adjustment is allowed)

 

[jfollows]

https://www.railforums.co.uk/threads/25-6-25-kv-electrification-removed.245616/page-4#post-6160292 contains examples of boxes and circles. The other two types of allowance described by @zwk500 hadn’t been invented then.

 

[zwk500]

https://www.railforums.co.uk/threads/25-6-25-kv-electrification-removed.245616/page-4#post-6160292 contains examples of boxes and circles. The other two types of allowance described by @zwk500 hadn’t been invented then.

Adjustment allowance is technically considered part of the runtime, so wouldn't ordinarily be shown in any timetable, even today.

 

[jfollows]

Adjustment allowance is technically considered part of the runtime, so wouldn't ordinarily be shown in any timetable, even today.

Thanks, I thought I hadn’t seen it explicitly, unlike the <> which has been around for a while.