Much of the effort in the lifting of OB 14 is indeed in preparing all the services crossing the bridge for the deck lift, which will be a princely 313 mm. NR have saved a lot of money by negotiating with the Statutory Undertakers to allow their cables to be lifted with the deck as it goes up, rather than having a traditional temporary services bridge alongside the main bridge. There is a 200 mm water main that will have a temporary route suspended above the deck, with teed in connections and valves that allows us to replace the existing main with a new polythene pipe in a protective steel sleeve along its original route. All the jacking will be done from trenches across the road, leaving the railway below free of obstructions.
It is also intended to keep a pedestrian route open over the bridge at all times, and the project will use their best endeavours to keep at least one road lane open as much as they can.
The bridge lifting works will start early next year. This survey is to trace the water main that is to be temporarily diverted. There's quite a lot of enabling works to do before the actual jacking up of the deck. The two side arches are to be concrete filled to ensure the bridge load capacity is maintained post lift.
The so called 6" masts were assessed as being inadequate in many situations. The usual mode of failure of masts is buckling at the bottom. To strengthen them one can add more steel to the lower third or so, or encase them in a reinforced concrete jacket.
The embedded masts can also suffer severe corrosion just above the concrete and these can be repaired in similar manner.
The design life for original and repaired OLE structures is 40 years (!)
Last Edit: Aug 12, 2017 13:17:47 GMT by BringBackBR: Bad grammar
Stations' tendency to be done later is really down to how the design is progressed. Programme pressure means that the project cannot wait until all the OLE design is done and dusted before physical work starts. As you chaps have alluded to, open railway is generally less physically restricted than stations, which means the preferred and easiest to install OLE foundation solution can be used. Piles for OLE can generally be quickly sized by looking them up in "allocation" tables and diagrams provided in the Overhead Line Equipment Master Index (OLEMI) whereas other foundation solutions require bespoke structural design, which need more detailed surveys and more design time. This is why you generally see the piles along the stretches of open railway going in earliest in the piece.
Where the new OLE interfaces with existing OLE and other users of the track, there will be other programme (possession) constraints meaning the more difficult foundations have to be prioritised. This was the case with Barking.
Any "what went wrong" investigation report should be available through a Freedom of Information Act enquiry I would have thought. I have mentioned the primary reason for the failure to deliver, I'm afraid I can't explain why the public comms weren't more accurate. The heavy civils were delivered to programme and under budget. I can say great effort and long hours have been spent trying to deliver the OLE steelwork but the wall was hit because repeatedly NR could not get the OLE designs in their hands in time to meet lead times for fabrication. I wish OLE were as simple as you seem to think it is!
I used to work for Tube Lines on the JNUP (Jubilee and Northern Upgrade Project), overseeing Thales' design for signalling structures. That was another example of an overseas designer not appreciating the difficulty of fitting new kit to a creaking and crumbling Victorian infrastructure. I ended up in their office coaching their very young design team to get stuff out the door.
The GOBe complies with current regulations by dint of track lowering and improving track fixity (i.e. slab track) to achieve the required clearances. The track lowering at WQR station necessitated lowering the platforms, which then introduced the need to make the platforms compliant with GI/RT7016 with respect to the refuge needed under the platform nosings. Considerable engineering effort went into minimising the extent of track lowering and of slab track to keep within budget and to minimise future track maintenance issues. There is one bridge, OB 14 at Crouch Hill that currently has "special reduced" electrical clearance, which will be jacked up in the future.
At Wightman Road we changed the originally proposed composite (steel beams with reinforced concrete on top) deck to "filler beam" (steel beams within the concrete) to maximise the electrical clearance. I got shouted at by the Route Asset Management team for not telling them!
The issue with clearances from platform to the pantograph horn is another country wide nightmare. Easy on the continent as they have low platforms.
Yes that's right. Some of the SPS has restriction on who supplies it and they are simply flat out. There are also issues with fabrication over here as the fabricators are so busy. The upshot is that practically all the steelwork will be in place come opening day, wiring to be done later.
Reading through this thread, perhaps I should clarify that the blockade was needed mainly for the heavy civils, which would have been impossible to achieve otherwise.