Here's a summary of a lecture about current progress on the East London Line extension. Please note that it's taken from my own notes and I apologise for any likely errors or inaccuracies. My note taking is not that fast and I still don't know how to use shorthand. Also sitting near the back row doesn't help. Railway Civil Engineers’ Association Evening Meeting
Institution of Civil Engineers 28 February 2008
The East London LineSpeaker: David Place, ELL Technical Advisor, Mott Macdonald
IntroductionTfL brand London Overground will the run East London Line which opens in 2010.
Procurement of Phase 1 works through a design & build contract awarded to the joint venture between Balfour Beatty & Carillion
The East London Railway ProposalPhase 1North section – Old Broad Street alignment to Dalston Junction
Central section - LUL East London Line Bishopsgate-Whitechapel to New Cross/NXG (North/Central section - 12tph increasing to16tph in Phase 2)
Southern connection onto existing Network Rail infrastructure-Crystal Palace-West Croydon 4tph
Phase 1A - extension to Highbury & Islington along NLL
Phase 2 – Extension to Clapham Junction (4tph)
Dalston Junction station – a new station & future multi-storey over-station development including 4 platforms (2 bay platforms + 2 through platforms + single track tunnel portal for possible future connection to NLL east of Dalston Kingsland???).
Design AuthorityMott Macdonald employed as an independent technical certifier for design approvals with LUL/TfL scrutinising. Use of hybrid LUL/NR standards.
A Brief History1825 Thames Tunnel construction begins
1843 The Thames Tunnel opens becoming a tourist attraction and eventually a commercial failure
1865 North London Railway City Extension opens
1867 East London Railway buys the Thames Tunnel converting it for rail traffic and establishes the New Cross-Wapping route
1878 Route is extended to Shoreditch
1986 North London Railway Broad Street branch closes
1996 Northern extension authorised through the Transport & Works Act (TWA)
2001 Southern extension to Clapham Junction authorised through TWA
2007 End of LU service
2010 London Overground service opens to mainline gauge 4-car Class 378 EMU 3rd rail DC traction
Phase 1 Progress to DateNorth Section
Enabling WorksTaylor Woodrow enabling works contract at the disused Kingsland Viaduct included vegetation clearance, deck waterproofing, drainage installation and assessment of brickwork arches & steel girder/brick jack arch underbridges. The majority of structures were found to be in good condition only requiring remedial works (covered below). The exception was a number of plated steel girder structures found to be in an advanced state of deterioration and required replacement. Since the underbridges were of sub-standard headroom clearance collision protection beams were fitted to all.
BridgesReplacement of 10 single span bridges with varying degrees of skewness is taking place. Typical bridge replacement was to cap the existing abutments with concrete cill beams and install pre-cast main girders with steel secondary cross beams. Features would include jacking points for future replacement of bearings and earthing points for the 3rd rail traction. The chosen structural form is a half through type bridge with shear studs on the cross beams to facilitate composite action with the deck slab.
Kingsland ViaductThe retained Kingsland Viaduct consists of 171 brick arches which each was inspected and assessed. Remedial works included pinning, re-pointing, stitching and grouting. Grouting is used in normal practice to fill voids and delamination of internal brickwork but voids need to be located. Initial grouting operations found that the take up was much less than predicted and radar surveys failed to detect druminess within the brickwork. The best method of detection was found to be injecting water into drill holes and watch for seepage.
Of all the arches, only three were found to be not capable of sustaining rail loading with extensive cracking to the intrados. These are at the site of the future Haggerston station. The viaduct was originally built for 3 tracks and was widened for a 4th track. Inspection found no physical connection between the two structures thus load transfer between the two was not possible. A strengthening option was considered involving piling below the piers to prevent differential settlement, removal of the spandrels and fill above, installing concrete saddles over the existing arches to relieve rail loading and reinstatement of the fill. The eventual choice was complete demolition of the arches to be replaced by a new steel half through bridge. Access to the new stations in this section will feature stairways and MIP lifts. Hoxton station concourse will be situated under arches.
Regents Canal BridgeThe existing structure is a 2 span steel structure featuring a central cast iron column pier. Due to the close proximity of a major power cable route, replacement of the existing column was ruled out. A new 45m single span steel bow string arch bridge will replace it. Strengthening of existing abutment foundations is required.
Kingsland Road BridgeThe structure was rebuilt into its present form in 1910. Its construction is 3 separate truss girders connected to each other by overhead bracing. Original alignment had 2 tracks running between each truss. New works taken place include the installation of two reinforced concrete troughs on the deck each carrying a single track. Bracing members were strengthened or replaced. The over the road bridge was completely repainted over a 9 month period requiring traffic management and extensive sheeting containment during removal of existing paint.
Bishopsgate Goods YardFacilitation of the new ELL route saw the demolition of GE19 at the site of Bishopsgate. The new alignment will cross Shoreditch High Street over the new Holywell viaduct, a bow string arch bridge. The tight alignment was further constrained by a listed building on the high street. To date the abutments have been constructed with transverse RC beams. The steel bridge has been assembled on site and will be lifted in next month March 2008.
The tracks over the new Bishopsgate viaduct will be enclosed in a protective concrete box due to future construction of a new large high-rise development beside and above. This also includes the new High Street station. Prior to construction of the substructure to Bishopsgate viaduct an archaeological dig was conducted on the site. Demolition of GE19 by main contractor Murphy required closure of GER lines to Liverpool Street over the new year period. The 6 tracks below were protected by crash mat as the GE19 brick abutments were cut down and then capped allowing brickwork to fall onto the mat. A possession overrun occurred as OHL work on the GER was not completed on time.
The new structure is an 84m span Warren-truss bridge assembled on site by Fairfield Mabey (consultants are Scott Wilson) with steel erection completed in February 2008. The bridge will be launched during a further 50 hour closure starting 4 May 2008. The launch method will use a self propelled vehicle (SPV) at the back end of the bridge while the front end will be pulled across the GER by jacking against steel cables fixed into the brick abutment on the opposite side. The concrete deck will be only 45% complete during launch to act as a counterweight at the back end until the launch reaches the western abutment. The lower soffit of the bridge is constructed of weathering steel that requires very little maintenance. This solution is particularly suitable as OHLE will be located close to the deck underside. However, the remainder of the structure is built from standard steel. This was a requirement of the maintainer, the reason was that any graffiti removal by grit blast method would strip away the protective layer of surface rust formed on weathering steels.
Central Section – Former LUL infrastructure In general, there were no gauging issues for the future rolling stock though clearance is tight in some places. Previous 4th rail track form will be replaced by slab track that is relatively maintenance free. The existing central six foot drain was found to be in various states of maintenance.
Shoreditch CuttingThe former LUL section has had its track removed and the cutting filled and levelled with the GER.
Whitechapel StationCongestion relief works include construction of a new cross platform footbridge. In future, Crossrail 1 will cross underneath the District line tunnels and to facilitate interchange deep shafts will be sunk either side of the station and removal of the cutting walls. Infrastructure protection measures include strutting of the cutting and construction of a crash deck. A disused stair and subway will be reopened as a secondary means of escape.
Wapping StationA new shaft will be sunk beside the station with an escape stairway.
(*Notes say Wapping shaft has provision for MIP lift???)The Thames Tunnel The tunnel underwent major refurbishment in 1990s with slab track. New cable runs are installed and change over to 3rd rail traction.
Rotherhithe stationAn unspecified secondary means of escape is to be constructed.
Surrey Quays stationNew stairs to be constructed.
New Cross Gate Depot Currently steel erection of the main sheds is underway. Construction of a new Carriage Service Depot will feature:
Stabling;
Heavy lift roads;
Train control centre;
Carriage wash facility;
Wheel lathe;
Facility for testing of 25kV OHLE pantograph;
London Overground intend to maintain trains on a two day wash cycle. Water usage by the wash facility will be 70% rainwater.
Southern SectionThe connection to NR infrastructure to West Croydon route will feature a flyover crossing NR Brighton lines north of New Cross Gate for the up line. The down line is located on the opposite side of NXG depot (
). A May 2008 closure of the Brighton mainline is scheduled for the launch of a 75m span truss bridge using a number of SPVs. Two bridge launching sequences were considered which one was to rotate the bridge over the mainline was discounted due to close proximity of newly constructed NXG depot sheds.
Phase 1A Northern connection to NLL Highbury & IslingtonDalston Western Curve– the existing alignment is a series of covered ways. Consisting of 3 tracks plus a more recent covered way structure for the additional 4th track. This single track covered way is to be filled in and the buildings above demolished.
Phase 2 South London Connection-Clapham JunctionIt is planned to re-use the abandoned track bed at Silwood Triangle to connect to the Old Kent Road junction. A grade-separated junction is required.
). A May 2008 closure of the Brighton mainline is scheduled for the launch of a 75m span truss bridge using a number of SPVs. Two bridge launching sequences were considered which one was to rotate the bridge over the mainline was discounted due to close proximity of newly constructed NXG depot sheds. 
