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.
I will have to see what's happening about extending STO and HRY platforms, not my bag normally.
One of the biggest problems with GWEP is the plethora of direct buried cables that makes piling for OLE a nightmare. GOBe piling has been much easier, apart from the risk of hitting unexploded ordnance!
The only civil/structural works in the GOBe scope are those directly required to achieve the electrification of the route. Generally the bridge works you see are all part of renewals and other works plans, apart from the parapet height extensions you might see springing up along the route. There happen to be some significant bridge replacements on the GOB route: the Lea Viaduct, River Lea Bridge 35, Palmerston Rd, Tottenham High Rd and Wightman Rd, all on GOB but not part of the electrification scope.
Platform lowering works such as at WQR have been required to match the track lowering needed to fit the OLE under the many low headroom bridges on the route. Platform extensions generally can be done in possessions so they are programmed to suit resource, but obviously they will be in place in time for the longer trains!
Bridge 32 over the Lea and the AFA works are separate from GOBe but obviously timed to make use of the blockade - not without some difficulty in the case of UB 32, as replacing the deck meant cutting off access for engineering trains and on-track plant.
There are two OLE bases to be squeezed in at the back of the Blackhorse Road platforms, adjacent to the stairs. The OLE foundations along Ferry Lane are concrete pads rather than the much preferred steel piles because the Vic line tunnels are running below.