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Home , East London line, Kingsland Viaduct, Metronet, North London line, Wapping, Whitechapel station

east line REBORN MAJOR PROJECT

REPORT London’s new Railway PLanning, design and construction of a new 10km rail route for 27|05|10 24 NEW CIVIL ENGINEER 27.05.1O | www.nce.co.uk www.nce.co.uk | 27.05.10 NEW CIVIL ENGINEER 25 LINE: INTRODUCTION

City slicker: The is a east end vital new link to London’s financial heart efficiency This week the London Overground East London Line opened a full service from West in “We are changing the “As a client team, we to in the north. In a remarkable face of London and worked very hard the way we think of towards letting the achievement, the project has been and use London in a main works contract delivered early. Jackie Whitelaw reports. permanent way. to programme” It is really dramatic” Peter Richards, Howard Smith, infrastructure director at to railway at Old Kent Road will allow a western London Overground east london trip to Junction via line REBORN Rye and Road and link to the Overground MAJOR Clapham Junction to were about to run out, and then existing infrastructure and main Junction Line. the Olympics came along, which works structures and rail sys- PROJECT The capital will have an outer finally tipped the balance and we tems to Carillion REPORT orbital metro railway under the could get on with building the as our main works contractor. banner of London Overground, project,” Smith says. “That is why we went for a interconnecting along the way Peter Richards was brought single NEC3 design and build with its Underground lines and in from the SRA to run the job main works contract. ne day after the serving 20 of its 33 boroughs; as infrastructure director for the “It has meant that BBCJV opening of the core and commuters will have oppor- LONDON OVERGROUND: THE FUTURE WHO’S WHO upgrade the East London Un- now dubbed London Over- has managed the interfaces, and route of the London tunities aplenty to avoid central derground Line that ran from ground, along with Mike Stubbs all the responsibility has rested Overground East bottlenecks when they are trying Client London Overground for to Gate as engineering director, and they with one party to get on and do O London Line last month, pas- to cross the city. since 1997. got stuck into design. the whole thing.” OVERGROUND Other parties London sengers were wandering around The key to creating this will Blackhorse Road Underground, had the idea to take a railway There had been a brief flirta- When Richards set up the job wide-eyed, taking in the wonder have been a £1bn Transport for East to Contractor Balfour Beatty into Hackney on a disused tion with funding the route he wanted to create momentum, of the capital’s newest rail route. London investment in infra- Barking Carillion joint venture viaduct that had once carried the through private finance. “But so he formed an integrated client Londoners who know the structure and new rolling stock. (BBCJV) North London Overground Line the ELL is a grey asset,” Smith team to manage the job and Gospel Contractor’s designers Scott detail of the Underground better This has reinvigorated and North West Oak from Broad Street Station, which says. “There is a lot of old in- drive its progress. This included than their bank pin numbers expanded the old East London to Watford & Wilson, Tony Gee & Partners had disappeared under the frastructure it would have been himself, Parsons Brincker- Junction were cooing contentedly to Line Tube line, reusing Victorian West Programme manager Parsons development in 1986. difficult to box up for PFI, and a hoff’s Ashok Kothari as head of Stonebridge Park themselves while looking at a infrastructure and introducing Dalston Junction Brinckerhoff It got Transport & Works Act PFI takes time to put together.” programme management and Haggerston Client’s technical adviser Mott map of the route which revealed some new modern landmarks Stratford (TWA) powers for the scheme, With the 2012 Olympics fast ap- designers from Mott MacDonald Willesden Queen’s Park MacDonald a whole new circuit board of along the way. Junction Euston Shoreditch High Street Rolling stock Bombardier which was then expanded again proaching, it was decided to go as technical adviser to the travel possibilities. As the first There are going to be huge Operator LOROL when it was realised the railway for a design and build option. project. section of ELL opened they benefits in terms of regeneration could interconnect with the It was a good decision. The Refurbishment work along could go from Dalston in Hack- and new jobs for some of the Shepherd’s Bush . Another scheme, built by a Balfour Beatty the route on some of the older ney in the north, south to the less developed parts of the City, Kensington (Olympia) EAST LONDON LINE IN BRIEF Transport & Works Act was ac- Carillion joint venture (BBCJV), structures like the Kingsland Docklands at Canada Water and rail-deprived Hackney will at Surrey Quays quired, and as the project by that opened early on 23 May. BBCJV Viaduct was let as enabling West Brompton Signalling,communications and then on to New Cross. From this last have a metro, and east and Queens Road stage had effectively become won the contract in October works contracts to Murphy and week, since the full line opened southeast London will acquire Peckham New Cross power systems, 3.5km of new part of Overground rather than 2006, started design immedi- Taylor Woodrow (now Vinci Denmark Hill on 23 May, the route will take some life changing infrastruc- New or refurbished viaduct from Underground rail, it was passed ately, and then started the major Construction). them as far into the south Lon- ture. Gardens Cross Whitechapel to Dalston Junction; to the newly formed Strategic structures in 2007. It got onto the “Refurbishment is risky and Clapham Clapham Gate don suburbs as West Croydon Around 33M passengers are Junction High Street Peckham 3.2km of track in south of Rail Authority (SRA) to manage. tunnel and south sections of the it was prudent to do some of and Crystal Palace. expected to be using the route To Richmond Rye Honor Oak Park Whitechapel to Surrey Quay ELL plans languished there site when the old East London that first before we let the bigger By early next year when phase every year by 2011, rising to a Forest Hill New stations at Dalston without a champion. But over Underground was closed in contract,” Richards says. 1a of the East London Line projected 39M by 2016. East London Line is vital for creating Junction, Haggerston, Hoxton at Transport for London it did December 2007 and handed over “And then, as a client team, opens, Croydon will have a direct “The really good part of this an outer orbital railway around the Sydenham and Shoreditch High Street; have its backers – Smith and his in late January 2008. we worked very hard towards connection to Highbury and job,” says London Rail chief capital. Phase 1 opened on 23 May. Crystal Palace West refurbishments at Whitechapel, managing director Ian Brown “From the start, we stressed to letting the main works contract Islington, and at Dalston travel- executive Howard Smith, under Shadwell, , at TfL’s developing London Rail everyone that this job is about to programme. lers will be able to switch onto a who’s remit the East London and Surrey Quays; an division in particular. And when delivering an operational railway “We didn’t let ourselves slip. KEY newly upgraded North London Line falls, “is that we are chang- Norwood Junction operational control centre; the SRA wound up and the route – infrastructure, rolling stock By doing that we created float Line to go east to Stratford and ing the face of London and the Phase 1 opened 23 May 2010 depot; and 44 four car was bequeathed to TfL in 2004 and operations,” says Richards. for the rest of the project and the Olympics or west to Willes- way we think of and use London Phase 1a completed by 2011 Electrostar 378 trains – 20 for they fought for, and won the “We have managed the integra- that has helped us come in early. den Junction and Richmond. in a permanent way. It is really Phase 2 completed by 2012 West Croydon the East London Line and 24 for funding. tion between these aspects and We are delighted to have opened And by 2012, construction of a dramatic.” the North London Line. “There was pressure to make given the responsibility for man- on 23 May, ahead of a pro- link from the East London Line There has been a plan to a decision as the TWA powers aging the interface between the gramme set back in 2004.” 26 NEW CIVIL ENGINEER 27.05.1O | www.nce.co.uk www.nce.co.uk | 27.05.10 NEW CIVIL ENGINEER 27 EAST LONDON LINE: Management

MaNAGING THE TEAMS Team work: The close cooperation culture of the job As BBCJV project director, Mike or £1.5M a day. has been vital to successful Casebourne has had to manage The job was divided into four construction of complex projects Working 640 professional staff, and 600 construction sections under the like Dalston Junction station designers off site in the offices of control of four BBCJV senior project Scott Wilson and Tony Gee and managers; northern civils under other designers. Andy Swift; southern and central Together civils under Paul Rasmussen; rail He is aslo responsible for 2,500 systems under Elliott Young and operatives on site at peak and the depot under Howard Williams. up to 1,000 people engaged in These were supported by design, as a team the offsite manufacture of all commercial and administrative the elements for the job all over managers within their teams and the UK. At peak, the project was reporting also to their department Collaboration between client, contractor spending £30M every four weeks directors. and supply chain was crucial as the construction project developed in scope, COMMUNITY RELATIONS writes Jackie Whitelaw. Community relations were a vital says head of communications for part of successful delivery of the London Rail Julie Dixon. “But we East London Line with full time always stress that the East London “That is why we went for a community relations managers Line is a regenerating railway with target cost design and build working for London Overground the priority being to give people east london contract rather than fixed price.” and BBCJV. access to jobs which has helped line REBORN But Richards points out that allay concern. there was always a total budget The usual issues of working “At New Cross Gate people were MAJOR and as the work grew, “we hours, noise and dust had to be unhappy at the idea of a 24 hour adjusted the scope to suit the addressed but it was either end of train depot. The solution was to PROJECT budget.” the project – at Dalston and New get the residents involved, listen REPORT “Is it safety critical?” was the Cross Gate where there were most to them and respond to their mantra. If it was, then the money sensitivities. concerns. For instance, the depot was found, if not, then as much “There was some resistance to the will have low level lighting so as cash was saved on each opera- idea of Dalston being gentrified,” not to create a nuisance.” hat is remark- tion as possible so there was able about the some to spare when needed. management That approach required close systems,” says Casebourne. venture finally got onto the line BBCJV drove itself along, SAFETY W of the London collaboration between the client “It was a requirement driven three months early at the end of and for added momentum it Overground East London Line team, BBCJV and its supply contract – for example to design January 2008. had a set of about one hundred construction work is that the job chain throughout the works. for three minute headways That is when the scope of the non-contractual milestones to The London Overground East has so successfully beaten its “The closely cooperative between trains.” job began to develop. There was hit, worked out with Parsons London Line scheme has had deadlines; particularly when the culture of the job has been vital,” “There were 6,000 require- the depot to add in. And two Brinckerhoff. an excellent safety record over scope of the scheme was some- says Balfour Beatty Carillion ments and about two thirds of bulk supply points for power. “In December 2008 we said the duration of the project. what fluid when the job was project director Mike Case- them were changed or modified “Those two 132kV bulk supply that we’d have all the structures, tendered. bourne. “It is one of complete as we all got on with the job,” points came on top of three 33kV track, and operational systems The site has twice recorded 1M Balfour Beatty Carillion Joint openness; no secrets, shared says Balfour Beatty Carillion traction substations already in complete to start test train accident free hours under the Venture (BBCJV) bid for and decisions and facing and solving engineering director Andy the contract, and those three had running 10 months later on 5 Reporting of Injuries, Diseases won the basic project against problems together.” Nettleton. “Without strong to change from pre-assembly October 09, and we did,” says and Dangerous Occurrences strong competition and with Richards agrees: “We have management of a resilient, to larger built insitu on site Stuart. “And from that date we Regulations (Riddor) 1995. the addition of many changes. some very dedicated people on “We had to design, responsive design organisation versions,” says Balfour Beatty “The scope increased, ran up to six of the new trains This was achieved in The final job is coming in at this project. There is a collabora- we would never have achieved so Carillion construction director every day for four months during December 2008 and again in £700M or thereabouts after new tive, positive culture which has construct, test, much in such a short time.” Adam Stuart. yet our design, which we finished the new November 2009. elements were added in and the all helped towards getting the commission and The key to pinning down the An enabling works contract construction and station buildings behind the The job hit over 1.5M amount of work required became job out the door on time and on scope was gaining access to the had beefed up the Victorian platforms; our track gives a very continuous Riddor-free hours, clearer as the construction teams budget.” deliver an operational old Underground section of the Kingsland brick arch viaduct commissioning period smooth ride and the Invensys and the current accident got stuck in on site. Actually the railway is two railway” route between Shoreditch and between Shoreditch High Street increased by only five signalling system proved fault- frequency ratio of reportable “We knew there would be months ahead of schedule. The Mike Casebourne, New Cross Gate. and Dalston. “But that still left months” less.” accidents to 100,000 man hours additional work in the central original opening date set at the “We pushed to get London BBCJV a lot of work in further “Also in December 2008 we worked is an excellent 0.12, a section but we couldn’t find out start of the job in 2004 was 30 BBCJV Underground to agree to get the assessment and strengthening,” Adam Stuart, BBCJV gave a date of 17 January 2010 to performance which recently how much until we took posses- June 2010. The full line opened route closed as early as possible,” says Stuart. hand over to trial operations and landed a coveted Rospa Gold sion of the railway from London on 23 May to coincide with says Parsons Brinckerhoff head The six “tunnel” stations on that very date we started the Award. Underground (LUL),” says the seasonal timetable change; of programme management between Whitechapel and week long process of handover “We have had a really big London Overground Infrastruc- and passengers were using the public,” Richards says. Ashok Kothari . LU agreed to Surrey Quays also needed much East London Line running when to Transport for London for trial push on the safety culture on ture director Peter Richards. central section of the route from “Right from the start, shut down the line in December more work than originally that project goes ahead. operations,” adds Casebourne. this project,” says health and “We also knew the depot, for 27 April. Not bad for a complex, when we signed the contract 2007 although it had originally thought and London Over- “One of the things I am most “In parallel the refurbishment safety manager Mike Davies. instance, had to be added in modern railway squeezed into a on 20 October 2006 we had wanted to keep it open until the ground decided to properly proud of here is that the scope of the tunnel stations was “We have focused on the but the contractor could not packed capital city. to remember that we had following April. refurbish them, he adds. has increased very significantly completed and the customer supervisors and gangers and put price that in the original tender “We are particularly pleased committed to design, construct, There was a slight delay “A grade separated junction yet our design, construction information systems were in some fun incentives like group because the designs from about getting the route into test, commission and deliver while Underground upgrade was also introduced to make the and commissioning period finished. Now customers are on of the month winning a fleece [rolling stock supplier] Bombar- service early as it will have a an operational railway, not just contractor stripped link with phase 2 to Clapham increased by only five months,” board and everything is working each,” he adds. dier were still being developed. huge benefit to the travelling its separate structures and rail out all of its assets but the joint Junction so as not to disrupt says Stuart. reliably.” WAPPING ROTHERHITHE Masonry construction HIGH WATER LOW WATER

Section View along the , c. 1835

28 NEW CIVIL ENGINEER 27.05.10 | www.nce.co.uk www.nce.co.uk | 27.05.10 NEW CIVIL ENGINEER 29 EAST LONDON LINE: DALSTON & NORTHERN STRUCTURES

Northern extension central section Central section Southern extension graphic: © www.paulweston.info 10m graphic: © www.paulweston.info Steel, Warren Precast concrete THAMES TUNNEL NEW CROSS GATE HOLYWELL VIADUCT SHOREDITCH HIGH SHOREDITCH HIGH truss bridge links up with the refurbished STREET BRIDGE box enclosure STREET STATION REFURBISHMENT WAPPING River Thames ROTHERHITHE FLYOVER 75m Bow arch bridge The East London line Masonry To avoid the need for construction span has its roots in the HIGH WATER points a much larger LOW WATER Skyway to Brunel’s construction grade crossing was Concrete ramp beneath the Thames required over the 32m BISHOPSGATE GE19 BRIDGE (c. 1825 and 1843). The existing, near capacity, 75m VIADUCT Steel, Warren truss bridge tunnel was refurbished Network Rail main lines. 1200t for waterproofing and to Section View along the Thames Tunnel, c. 1835 A 1200t Warren truss Concrete Network Rail of steel the north take slab track. bridge with a 75m span ramp main lines BISHOPSGATE was employed GOODS YARD 400m 84m CANADA GREENLAND WATER North 1/4 mile Prime develop- viaduct length span DOCK New Cross 6m 100m SHADWELL London THAMES TUNNEL ment area platform length DLR BASIN ROTHERHITHE NEW RD SE16 Station line 10m 300t NEW CROSS GATE ROAD E1 Shadwell Victorian road bridge 22m Rotherhithe Surrey Quays DALSTON LANE E8 above ground of steel Station replacement FLYOVER Great Station Station Dalston 21 - 23m Eastern Junction WAPPING HIGH STREET E1W On embankment spans GE19 main line WHITECHAPEL RD E1 Canada Water REGENTS CANAL Whitechapel COPE ST SE16 Haggerston BRIDGE Station Station New Cross Gate To Croydon BRUNEL RD SE16 Station RIVER Victorian road bridge Station KINGSLAND ROAD E2 Surrey Canal Precast Wapping THAMES replacement deck Road bridge Hoxton City line Station LOWER RD SE16 Station Shoreditch Precast NEW CROSS GATE Rails mounted on High Street panels Escape shafts DEPOT DALSTON STATION PODIUM Portal frame SLAB TRACK concrete block NEW CROSS ROAD SE14 Station sections sleepers A massive and complex 16m Masonry Vent Used on the new structure designed to BISHOPSGATE shaft depth viaducts and in BOOTED SLEEPER - SECTION support multi-storey Kingsland Viaduct, Cast iron Mass concrete slab VIADUCT SHOREDITCH struts tunnel sections, For areas requiring the most noise development and AIR RIGHTS DEVELOPMENT refurbished masonry track slab suppression sleepers are mounted in accommodate Cross- arches and addition STATION BOX WAPPING Made ground improves stability, an absorbent membrane rail of underbridges ENCLOSURE STATION noise suppression Boot Rail mounted - DETAIL and maintenance (absorbent on sleeper Podium slab VENT Drift intervals Extension for 10m membrane) HOXTON SQ N1 Air rights - To create a second completion 2012 Precast concrete Station Bishopsgate Goods Yard means of escape New opening New opening box enclosure 21 -23m for the station, London clay/ thin layer To Clapham protects the line spans, shafts were sunk HOLYWELL SHOREDITCH Pile cap group Concrete Track sections Concrete sleeper Junction from future 34m at either side of a 1,366 VIADUCT HIGH STREET development trough takes - lengths to 30m station tunnels Victorian, brick Mass concrete slab OLD KENT ROAD SE1SE1 foundation piles BRIDGE works pile depth entrance lined, smoke vent Mass concrete Thanet sands slab track suit project

blocks of up to 17 storeys that are for Dalston Kingsland Guy links,” he says.This gives a total apartment building which are be caused by such heavy point Dalston Junction station is a massive, DALSTON set to be constructed on top. Anstiss recalls. “In some places of 1,250kg of reinforcement per expected to be up to 7,000t. Here, loads. Once the beams were in complex structure that has been designed Within weeks of work starting, there’s an awesome amount of linear metre in some locations. steel I-beams have been used as place, the diaphragm plates were JUNCTION what had once appeared to be a reinforcing steel. One section However, in 19 beams, even part of the permanent reinforce- welded insitu, the voids between to support multi-storey buildings and to generously-proportioned, open of beam has over 100 H40 bars this heavily reinforced concrete ment, with pairs of I-beams the plates were filled with grout n theory, building a new cutting had become a highly at the top and bottom of the was unable to support the joined top and bottom with and then reinforcement cages accommodate the potential four-track four-platform congested construction site, with downstand beam, and multiple anticipated point loads from the diaphragm plates. placed in and around the beams line, as Margo Cole discovers. And Adrian station at Dalston Junction over 30 pieces of major plant These pairs of beams weigh to tie them into the podium slab I could have been fairly involved in excavation and pile up to 90t each, and span up before the concrete was poured. Greeman focuses on the array of civil straightforward. installation, as the London Over- to 33m. They sit on specially In all, there is 1,000t of structural engineering work in the northern section Admittedly, space was very ground East London Line team designed bearings supplied by steelwork in the new station, tight, but the new line runs set about building a 250m long Freyssinet that weigh up to 3t most of it in these massive linking the Victorian Kingsland Viaduct to through an existing cutting, so by 40m wide podium slab and its and are capable of handling the beams. surely it wouldn’t have been too supports. uplift and the rotation that could The downstand beams span the old East London Line at Whitechapel. much of a challenge to build a The loads from the proposed between walls and columns that roof slab over a section of the apartment blocks will go into sit on pile caps up to 2m deep, tracks and put a station building downstand beams built into the the largest of which takes up an on top – would it? 500mm thick podium slab, and “One section of area of 3,600m2. Beneath the pile The reality is not quite so from there into a series of walls beam has over 100 caps are heavily reinforced bored east simple. The area taken up and columns supported by deep H40 bars at the top concrete bearing piles, most of by the railway line as it runs piled foundations. The new plat- which are 650mm or 750mm in london line through the heart of Dalston is forms will sit under the podium and bottom of the diameter, and sunk to a depth of extension prime development land and an slab, just above pile cap level. downstand beam and 26m. However, at one end of the important area within Hackney’s For the most part, the down- site, provision has been made MAJOR regeneration plans. As a result, stand beams are 1m deep, and multiple links” for the possibility of the second PROJECT a slab had to be built over the were cast in situ along with the Guy Anstiss, Crossrail line passing diagonally tracks not only to support the deck slab. Some of the beams BBCJV beneath the East London Line. REPORT station building but also the were very heavily reinforced, In the original design, a raft loads from a series of apartment as BBCJV section manager Complete: A new train zips into Shoreditch High Street Station foundation would have 30 NEW CIVIL ENGINEER 27.05.10 | www.nce.co.uk www.nce.co.uk | 27.05.10 NEW CIVIL ENGINEER 31 EAST LONDON LINE: DALSTON & NORTHERN STRUCTURES

HOXTON AND HAGGERSTON STATIONs head Tight spot: Hoxton station was snugly fitted under Kingsland viaduct

The new station at Hoxton is and the jacks removed to allow Crossrail crossing: Piling at Dalston included working around the Crossrail route built inside an existing set of the brickwork to sit back down rail arches, with the concourse on top of the frame. The BBCJV’s constructed by punching through engineer Scott Wilson had to carry the brick piers. out considerable finite element analysis to ensure the new design To create this space, ground could carry loads from the tracks engineering specialist Bachy first above. For Haggerstone Station, installed low headroom mini-piles the old viaduct was demolished either side of each existing pier, and a new station built. and a ground beam was cast on top. Holes were then drilled through the brickwork, and needle beams threaded through the top of the pier, and jacked off the ground beam to support the arch roof while the material below was removed to form the required space. New columns and a lintel beam Transfer beam: Massive steel beams will carry were then grouted in place to form properry developments above Dalston Station a portal frame within the pier, Catalyst: The station at Dalston Junction is expected to trigger regeneration

spanned the line of the weighed up to 13t, and required turned into a “hybrid”, with the 300mm in diameter. “We wanted bentonite before we hit the of near dereliction, what was tunnel, carrying the building two splices to enable them to be post-tensioning remaining in 750mm diameter piles, but when sand, and then keep excavating OTHER once a huge, two-level railway “We established a loads into the ground. But there lowered into the pile bore. place on the eastern half, while we decided to keep the bridge, through the bentonite,” says unloading depot with a half truck route out of was concern about differential An inventive piling solution the parapet on the western side the question was: ‘how do we get Anstiss. “Then we had to grout STRUCTURES kilometre length of vaulted brick settlement between this section was also needed as part of the was demolished to allow the the rigs in?’” says Anstiss. under pressure to replace the arches supporting its rail tracks the Bishopsgate of foundation and the rest of remedial work to the Forest buses to turn off, with this half Rigs large enough to sink bentonite, and at the same time he northern section of has become the largest potential Goods Yard using a the site, which was piled, so an Road bridge, which spans the of the bridge supported by one 750mm diameter piles to the install the 18m long reinforce- the London Overground development zone in London Bailey bridge” alternative, piled, solution was rail cutting at the southern edge of the walls designed to take the depth required would not have ment cages.” East London Line, and is ripe for major office and developed. of the podium slab. podium slab loads. The new pier fitted under the bridge structure, Now that Dalston Junction T running mostly on once residential schemes. Andy Swift, Two rows of bored piles have In the original design, all of wall is topped by an I-beam that so the design was changed to station is complete, much of the abandoned Victorian viaduct, Early work for the BBCJV BBCJV been sunk on each side of the this post-tensioned concrete is tied into the existing bridge 450mm diameter piles instead. massive civil engineering work has to make a swing eastwards meant clearing thousands of tunnel line, topped with pile structure was due to be demol- reinforcement. “That would have worked, but will go unnoticed by passengers, as it reaches the edge of the tonnes of brick rubble from the caps that support walls carrying ished and replaced by a new Beneath the wall is a large pile we had a problem with ground but during construction it was . This enables it northern half of the nearly 5ha the podium slab, the station bridge with no parapet on one cap and a total of 66 piles, each conditions,” says Anstiss. “It one of the most complex parts of to link up with the old London site. This was the residue of concourse and the multi-storey side, to allow buses to come off looked OK from the boreholes, the entire scheme. Underground East London pre-contract demolition works its curry restaurants. The trucks development above. the Kingsland Road and into a but when we started piling, water At maximum there were 306 Line route to south London. which took away many of the old then passed over a still intact “This acts as a ground level new bus station being built on started boiling up from the base. operatives working on this part Two major bridges, substantial arches. Some remain, including Network Rail bridge, known as bridge, one of the biggest on the the podium slab. However, the “We wanted 750mm It meant that 450mm diameter of the site, and the major plant new viaducts, reshaped cuttings the famous and now listed GE19, whose later demolition job, so they can put the Crossrail BBCJV felt that full demolition diameter piles, but wouldn’t really work because used to construct it included a and a new, relocated station at Braithwaite brick arches, built by Murphy and replacement by tunnel in much later without too would be a complex process, as there wasn’t a rig available to 64m concrete pump – the biggest Shoreditch High Street, are just by Victorian civil engineer John BBCJV was one of the largest much settlement,” says Anstiss. the structure is full of services when we decided to allow us to manage the boiling available in the UK at the time. some of the works needed to Braithwaite in the 1830s. jobs in this section. It crosses It sounds straightforward, but that would have had to be keep the bridge, the sand.” With construction starting make the link. “We established a truck route a six track wide cutting for the each of the 40 piles in these four diverted at great cost. It was question was ‘how do Instead, the design had to on the apartments that will sit The new section takes the line out of the yard using a tempo- main lines between rows measures between 1.8m also very close to neighbouring be changed again for 300mm on top of the podium slab and through and across Shoreditch rary Bailey bridge,” says Andy Street Station for the East Coast. and 2.1m in diameter, and has properties that would be affected we get the rigs in?’” diameter piles, with construction passengers starting to use the High Street, and on into the Swift, BBCJV project manager Just beyond this bridge the been bored to a depth of 40m – by noise and vibration during Guy Anstiss, carried out in a sequence that bright, airy, stainless steel lined historic Bishopsgate Goods for the northern section civils line dips into cutting and then only just above the chalk layer the demolition. saw a series of casings driven, concourse, this ultra modern Yard area, once one of the works. The temporary bridge underground at the Valence that underlies the London clay. Instead BBCJV proposed that BBCJV with the piles augered out inside station will soon be a centre industrial wonders of Victorian took construction traffic over Road portal. The brick rubble The reinforcement cages alone the structure be retained, and them. “We had to introduce point of modern Dalston. London. After three decades famous , known for the trucks carried was used 32 NEW CIVIL ENGINEER 27.05.10 | www.nce.co.uk www.nce.co.uk | 27.05.10 NEW CIVIL ENGINEER 33 EAST LONDON LINE: DALSTON & NORTHERN STRUCTURES

to infill part of that cutting, concrete. “We used limpet vibra- pile” system to bore them, with primarily to safeguard the line 85m span over the six Liverpool the Bishopsgate Goodsyard all the emergency services, local reshaping the gradient and “The station tors on the formwork which gave polymer support, into water from future construction and Street main lines, went well. It site. There, the firm welded the authorities, and others for a road approach to the new GE19 enclosure is really us issues of noise and vibration saturated gravel. development planned for the was fully assembled on tempo- curving steel beams to form the closure,” Swift adds. The site bridge. It also helped fill another a permanent crash to manage, since this is a busy Piles were “substantial” says entire Bishopsgate area, with rary falsework on the track bow and set the vertical hangers. needed proper preparation for part of the cutting which area with a lot of residential Swift, between 1,200mm and over-site “air rights” construc- alignment in the space which A critical part of the job the crane which arrived on some continued on the Bishopsgate deck to keep trains property around,” says Swift. 1,500mm diameter. tion around the station, possibly became the approach ramp, and was a major crane lift for the forty trucks and took several side, swinging around towards running while work Clusters of five bored piles The larger diameter was used including a 40 storey high rise push launched into place. completed 330t bowstring arch days to assemble. Ground had to . support each end of a series of to achieve a shorter pile in a few office development. Work is “It was powered over using a bridge, using the 1,200t Sarens be properly cleared, and an area This was where the original is done later by the single pile caps as wide as the places, allowing the pile end to imminent, although delayed multi-axle transporter provided crane on a May weekend in 2008. piled to support the crane. Shoreditch Station was sited. developer” viaduct on which sit each pair remain in clay and avoiding the temporarily by the economic by Abnormal Load Equip- “The lift only took a couple of The viaduct continues west The new Shoreditch station Andy Swift, of the columns that support need for the polymer. Bachey situation. ment” says Swift. A 30m long hours but 12 months of prepara- of Shoreditch High Street with is set in the length of the old the viaduct above. One cluster Soletanche was subcontractor “The station enclosure is nose section was added for the tion were needed beforehand” the Holywell viaduct, curving goods yard, along much of a BBCJV was bored very close to London for the piling. really an expensive, perma- launching at the front end and says Swift, not least because the sharply to take the line back new viaduct which carries the Underground Central Line The longer piles carry the nent crash deck to keep trains the ALE transporter sat at the busy crane is much sought after. across the street as it links north track through the yard space tunnels and monitoring equip- heavier loads in the central part running while work is done later rear end. “It was a balancing “We also had to coordinate to the existing Victorian brick and out across Brick Lane. This ment was set up to give early of the viaduct where the 200m by the developer,” says Swift. exercise to keep the nose up” viaduct further on. Five 20m Bishopsgate viaduct carries the warning of possible distress. length of the new Shoreditch It is built from precast portal says Swift “so we concreted the spans were needed, built close line on 400m of a new concrete and are connected by a concrete Fortunately there was none. station is located. The entire frame sections attached to the back end deck and added more alongside a listed and untouch- elevated way, some 10m or so slab which forms the deep Piles are as much as 30m deep station at rail level is enclosed in viaduct at 7.5m intervals. Three weight, leaving the front deck “The GE19 bridge able building on Shoreditch above ground. trackwork trough between them. under the station section and a precast concrete box, creating 2m high panels are bolted to to be done later. The launching was powered over High Street, running within The viaduct comprises pairs Spans between are 21m to 23m around 22m deep elsewhere. a kind of “tunnel in the air”. The each side of these before an was done with the strand jacks using a multi-axle 330mm of it at one point. of mainly 6m high columns long apart from an extra long They were driven into London box tube comes in two widths, insitu top deck is formed and between the permanent concrete This part of the work was which are mainly circular or 34m span across the street at the clay on which much of the site a central portion enclosing the poured. abutments being used as the transporter. It was a preceded by significant archaeo- elliptical in cross section. They station entrance. rests. 100m long platforms and two There were challenges on the launch fulcrum, and the ALE balancing exercise to logical digging within the old carry a large 3.5m deep edge Concreting for these beams “The clay rises from the smaller parts extending the longer GE19 bridge to the east transporter at the rear end.” Holywell Yard. The Museum of beam on either side. “In fact was reasonably complicated Brick Lane end somewhat as station enclosure at either end; of the station site. This was West of Shoreditch Station, keep the nose up” London was delighted by the the depth varies at centre span since they required a mass of you approach Shoreditch,” says there is an option for future fabricated and assembled by the line crosses Shoreditch Andy Swift, discovery of the remains of an giving them a slightly arched heavy T40 bar reinforcement, up Swift. There is terraced gravel expansion of the platform Fairfield Mabey. The assembly High Street on a 35M span BBCJV old monastery, including foot- shape” says Swift. to five layers thick, which meant beneath and for the longer lengths into these. of the Warren truss bridge which bowstring arch bridge fabricated ings and columns, various burial The beams form the platforms care was needed in placing the piles that meant using a “wet The point of the enclosure is carries the new railway on a by Fairfield Mabey partly within sites, plates and knives.

New link: The line runs on a mixture of new and refurbished viaduct from Dalston to Shoreditch

Shoreditch High Street: A 35m span bow arch bridge is lifted into place

GE19: The bridge was launched over six mainline railway tracks WAPPING River Thames ROTHERHITHE Masonry construction HIGH WATER LOW WATER

Section View along the Thames Tunnel, c. 1835

34 NEW CIVIL ENGINEER 27.05.10 | www.nce.co.uk www.nce.co.uk | 27.05.10 NEW CIVIL ENGINEER 35 EAST LONDON LINE: SOUTHERN SECTION

Northern extension central section Central section Southern extension graphic: © www.paulweston.info 10m graphic: © www.paulweston.info Steel, Warren Precast concrete THAMES TUNNEL NEW CROSS GATE HOLYWELL VIADUCT SHOREDITCH HIGH SHOREDITCH HIGH truss bridge links up with the refurbished STREET BRIDGE box enclosure STREET STATION REFURBISHMENT WAPPING River Thames ROTHERHITHE FLYOVER 75m Kingsland viaduct Bow arch bridge The East London line Masonry To avoid the need for construction span has its roots in the HIGH WATER points a much larger LOW WATER Brunel’s construction grade crossing was Concrete ramp HEbeneath the Thamesa ding required over the 32m BISHOPSGATE GE19 BRIDGE (c. 1825 and 1843). The existing, near capacity, 75m VIADUCT Steel, Warren truss bridge tunnel was refurbished Network Rail main lines. 1200t for waterproofing and to Section View along the Thames Tunnel, c. 1835 A 1200t Warren truss Concrete Network Rail of steel take slab track. bridge with a 75m span ramp main lines BISHOPSGATE South was employed GOODS YARD 400m 84m CANADA GREENLAND WATER North 1/4 mile Prime develop- viaduct length span DOCK New Cross 6m 100m SHADWELL London THAMES TUNNEL ment area platform length DLR BASIN ROTHERHITHE NEW RD SE16 Station line 10m 300t NEW CROSS GATE MILE END ROAD E1 Shadwell Victorian road bridge 22m Rotherhithe Surrey Quays DALSTON LANE E8 above ground of steel Station replacement FLYOVER Great Station Station Dalston 21 - 23m Eastern Junction WAPPING HIGH STREET E1W On embankment spans GE19 main line WHITECHAPEL RD E1 Canada Water REGENTS CANAL Whitechapel COPE ST SE16 Haggerston BRIDGE Station Station New Cross Gate To Croydon BRUNEL RD SE16 Station RIVER Jubilee line Victorian road bridge Station KINGSLAND ROAD E2 District line Surrey Canal Precast Wapping THAMES replacement Hammersmith deck Road bridge Hoxton City line Station LOWER RD SE16 Station Shoreditch Precast NEW CROSS GATE Rails mounted on High Street panels Escape shafts DEPOT DALSTON STATION PODIUM Portal frame SLAB TRACK concrete block NEW CROSS ROAD SE14 Station sections sleepers A massive and complex 16m Masonry Vent Used on the new structure designed to BISHOPSGATE shaft depth viaducts and in BOOTED SLEEPER - SECTION support multi-storey Kingsland Viaduct, Cast iron Mass concrete slab VIADUCT SHOREDITCH struts tunnel sections, For areas requiring the most noise development and AIR RIGHTS DEVELOPMENT refurbished masonry track slab suppression sleepers are mounted in accommodate Cross- arches and addition STATION BOX WAPPING Made ground improves stability, an absorbent membrane rail tunnels of underbridges ENCLOSURE STATION noise suppression Boot Rail mounted - DETAIL and maintenance (absorbent on sleeper Podium slab VENT Drift intervals Extension for 10m membrane) HOXTON SQ N1 Air rights - To create a second completion 2012 Precast concrete Station Bishopsgate Goods Yard means of escape New opening New opening box enclosure 21 -23m for the station, London clay/ thin layer To Clapham protects the line spans, shafts were sunk HOLYWELL SHOREDITCH Pile cap Lambeth group Concrete Track sections Concrete sleeper Junction Crossrail from future 34m at either side of a 1,366 VIADUCT HIGH STREET development trough takes - lengths to 30m station tunnels Victorian, brick Mass concrete slab OLD KENT ROAD SE1SE1 foundation piles BRIDGE works pile depth entrance lined, smoke vent Mass concrete Thanet sands slab track suit project

to build the under rail structural To prevent movement of the The cost of “several millions” Negotiating exisiting tunnels, contracts TUNNELS elements during the ELL works. walls, work had to be done in has been met by the Crossrail and Victorian structures was all in a The ELL team also found itself two phases. In each phase, the project. & TRACKS involved in some other advance existing platform was broken day’s work for the East London Line team works for the Crossrail team. out in bays 4m to 9m long, new Wapping as it worked to construct and renovate he biggest civil engi- Crossrail has almost no space precast struts were laid across the At Wapping station the main neering challenges were in the streets above Whitechapel trackbed and then a pilecap was entrance uses the Brunel tunnel the railway. This section of the project at Whitechapel and for work platforms from which constructed at each side of the shaft to accommodate two lifts also involved work to ensure the new T Wapping as part of the to construct its excavations. To cutting. and a spiral staircase but at the need to provide all the under- find space it has prepared for a “We used hefty 406mm diam- other end there was no obvious structures did not interfere with planned ground stations with secondary major bridging structure to be eter tubular steel struts as tempo- second escape route. means of escape (SMEs) built over a 70m length of the rary support until the piles were “There was a brick lined smoke works for the Crossrail line which crosses Whitechapel cutting. cast,” says Bradshaw. “The struts shaft however, about 11m across” the route. Adrian Greeman reports. Whitechapel This “crash deck” work plat- were later reused for excava- says Bradshaw. It dates from At Whitechapel, a relatively form will need to support major tion support elsewhere on the the days when steam trains ran simple steel truss bridge sufficed equipment and heavy plant and project.” Circular voids had to underground which they did for the SME, with lattice towers demands correspondingly hefty Wapping: Here, the line runs south into Brunel’s twin bore Thames Tunnel be left in the pilecaps for later until early in the 20th century. on the platforms and steel stair- foundations, explains BBCJV sinking of the piles needed to Either side of this 16m deep vent, cases to link to an emergency engineering manager for central In order for the Crossrail support the Crossrail work plat- it was decided to sink shafts in street level exit. and southern sections Andy “We used big 530mm crash deck piles to be installed form. which steel staircases could be But on either side of Bradshaw. During its work, the diameter tubular BBCJV had to remove the old Two contiguous piled walls built, linked to the platforms by east london two large ELL team installed for Crossrail ELL service platforms at the base some 3.5m apart across the tracks cross passages at the base that line REBORN excavations will be required for two rows of 600mm diameter steel struts as of the 10m high Victorian brick were also cast to form the walls were created by breaking through the planned Crossrail station piles on each side of the ELL temporary support buttress-and-coffer retaining of the future Crossrail station the thinner infills between the MAJOR which will sit above the Crossrail tracks, with some careful design walls that make up the ELL connecting passage. A thick- retaining wall buttresses. tunnels but below the ELL. required to give pile lengths during the casting” Whitechapel cutting. This was a ened section of the track bed The original plan to form a PROJECT The two subterranean Crossrail which stopped short of the Andy Bradshaw, tricky job because the toes of the makes a roof slab for this pedes- rectangular box shaft with big REPORT concourses will be linked by a Crossrail track tunnels. “The BBCJV retaining walls had to be braced trian tunnel which will be exca- 1100mm secant piles did not pedestrian underpass beneath pile depths were limited to 10m,” off each other throughout the vated, when needed by Crossrail, work within the overall construc- the ELL tracks, and it made sense Bradshaw says. works. without disrupting the ELL. tion programme. A value engi- 36 NEW CIVIL ENGINEER 27.05.10 | www.nce.co.uk www.nce.co.uk | 27.05.10 NEW CIVIL ENGINEER 37 EAST LONDON LINE: SOUTHERN SECTION

Excavation through Wapping station: Orange temporary struts NEW CROSS GATE DEPOT brace the original 16m high buttress-and-coffer what had been The new ELL depot sits on old brick retaining walls while the original struts are thought to be London replaced with new, stronger white lookalikes sidings which for some years Clay instead turned had become a local authority site for impounded cars out to be rotten says Mark Walker of BBCJV timbers, possibly who supervised the depot from some long- construction. forgotten wharf The depot is domnated by the Whitechapel: Vital interchange four-track, four-crane, four train rolling stock maintenance facility and its three storeys of offices all housed in a huge 90m by 40m neering rethink suggested by 12m high rectangular steel- sinking jacked caissons with framed, steel-clad building. Inside mucking out by long reach exca- Depot: The South London site is a huge 90m by 40m steel framed structure the depot are three raised tracks vator “which paid a health and enabling clear access below safety dividend because you the trains. The fourth track is don’t need anyone in the shaft equipped with synchronized jacks until you have reached forma- capable of lifting a whole train tion level and pumped out,” says in one minute for the purpose of Bradshaw. bogie changing. This went well until the time Another 90m building, split came to make the first cross longitudinally into two, has one passage, excavating through track dedicated to a twin-headed what it had been thought would wheel lathe and a second in the be firm London clay. Instead old other half committed to heavy rotten timbers, possibly some cleaning and painting. It also temporary works left in place by has a blast and fire proofed top builders of the wall, were encoun- floor dedicated to an operational tered. These timbers posed a control and signaling centre problem because, once disturbed, which allows signallers 10 it was realised that they were minutes to safey shut down all providing a water flow route from rail systems in the event of a fire. the terrace gravels above. “And Hot stuff: Thermal welders at work Junction: The depot is just to the east of the massive New Cross Gate flyover since the Thames is just next door the water was not going to new steel to take the loads. Apart carriageway road and pedestrian strip of bridge deck with the two transverse I-beams were to form a new cutting taking traffic closures on weekends stop,” says Bradshaw from the complexity of this work South of pavement and were supported fibre optic cable intact while the then attached underneath the the connecting track down when Football Club had Initial grouting was just the job was a major exercise in in the middle by a central pier. rest was rebuilt with new precast new deck, to support the power and around, with a slab placed home games, says Bradshaw. washed out and a programme of logistics, with a crane at the top the thames Originally rail tracks ran either concrete beams. “And then we line slab, on either side of its across the top of this cutting to minipiling between buttresses of the shaft juggling old and new side of the pier but now they only had to move the cable once support pier. carry the up-line. The new grade New Cross Gate Flyover and shafts was devised to form pieces of steel around both the nce the ELL emerges only run on the western side. onto the new part and finish the With the power cable slab load separated junction has been A much bigger grade separated a grout curtain to cut off the permanent struts and three sets from its tunnels just The cast iron piers did not construction,” says Bradshaw. transferred to these temporary built to avoid service disruption crossing was needed near the flow while the cross passage was of 250kN temporary props. past Surrey Quays meet modern derailment resist- beams, the pier could be in the future when the project to end of the renewed East London completed. On the other shaft, Marc and Isambard Brunel O onto conventional bal- ance standards and had to go. At Rotherhithe New Road Bridge demolished. A third steel I-beam connect the East London Line Line section where it merges forewarned, the grout curtain had accessed their Thames lasted track, it might be thought the Cope Street bridge, an initial At the second bridge, Rother- was then installed between the to Clapham Junction gets under with and uses the existing was created before any trapped Tunnel works via a shaft on the there was less to do. scheme for a single unsupported hithe New Road Bridge, an even temporary ones, to be a perma- way. Network Rail slow lines at New ground water was disturbed. south bank of the Thames. But renewing bridges, span was dropped because the more expensive utility diversion nent support, while the outer Further south, a third road Cross Gate on the route south Meanwhile inside the smoke To make a lasting contribu- providing for new connections deck beams would have been too was needed to handle several two were removed. bridge was replaced, this time to Croydon and Crystal Palace vent a series of Victorian cast iron tion to London’s engineering to the mainline and future deep. Instead new concrete piers high voltage cables which served The new Rotherhithe bridge with the straightforward demoli- at New Cross Gate. New Cross struts needed upgrading. Two heritage, BBCJV cast a whole London Overground extensions were installed but set back from most of South London. These has one single span. It is longer tion and lifting in of a new deck Gate flyover avoids the need for levels of three rather elegantly new floor in, sealing it off and installing big flyover at New the live track, creating one long were embedded in a concrete than before but does not run the with a 1,000t crane. Apart from a four-track ladder of switches shaped struts, with flared ends, from the tunnel and trains, so Cross were all significant chal- and one short span. block which had replaced one of full length of the old bridge’s finding space between buried and crossings to carry the ELL had to be replaced. Architec- leaving it available to the Brunel lenges. Simple replacement of the the original jack arches between two spans. Instead the far abut- services to put crane outriggers, trains across four near-capacity tural heritage considerations Museum to develop as additional And there was the building of deck above was complicated two I-beams. ment was built outwards on the main problem was to avoid main line tracks onto its own dictated that the replacement exhibition space, including a a brand new carriage servicing by the high concentration of Rather than a double move for the disused side of the cutting. line which runs past the new struts should resemble the origi- chance for visitors to see the orig- depot to add into the mix. services carried within the decks, the cables at an overall cost of Rebuilding the bridge in this service depot. nals as far as possible. The upper inal shaft structure. most critically a fibre optic cable. £1.4M, and some risk of blacking way produced a net saving to The connection takes north- struts were removed completely Other station work was also Cope Street Bridge Diverting it to a temporary out a big part of the conurbation, the client of around £1M, says Renewing bridges, bound trains heading for the and new steel struts installed in complex. Two significant bridges carry bridge during the work would BBCJV devised a system to leave Bradshaw. providing for ELL off the main slow line and their place, but the lower struts “After contract award the client busy South London road have been very expensive – the block intact and rebuild the Further south in the Silwood connections to the then up an inclined concrete were more difficult because it decided to completely refur- connections across the line around £250,000. “And diverting rest of the bridge around it. depot, there is to be an eventual ramp to a 75m steel bridge which was hard to see exactly how they bish the station buildings and just after Surrey Quays station, it back afterwards would have The bridge was tackled in connection to the South London mainline and future spans the four tracks. A short connected at the wall. platforms bringing them up to where it is still in cutting, rising doubled that,” says Andy two halves in order to leave a Line. Points suffice to make London Overground 32m steel span continues the Rather than risk displacing modern standards; this devel- out of the river tunnel section to Bradshaw, BBCJV construction carriageway open for busy traffic. the transition on the up-line 10m wide bridge from a concrete anything the lower struts were oped into interior demolition surface running. Both of these engineering manager for the Most of one side was demol- into London, but the down-line connections and a pier onto another inclined cut away in the centre and new back to bare walls and even some were old Victorian bridges, 10m section. ished first, leaving the power trains will have to dip under the flyover at New Cross concrete ramp that carried the steel sections were inserted. of those were reconstructed,” says wide, comprising parallel cast Costs were contained after a line slab in place supported on up line to travel west to Clapham were big challenges trains through the new depot Around the remaining cast iron BBCJV stations project manager iron I-beams and masonry jack value engineering study devised its portion of the pier. Once the Junction. and onto the ELL’s dedicated lengths a sleeve was devised in Phil Wharton. arch infills. Both carried a single a scheme that left the narrow new steel beams were installed, Secant piled walls were used line. 38 NEW CIVIL ENGINEER 27.05.10 | www.nce.co.uk EAST LONDON LINE: SOUTHERN SECTION

The most complex part of the operation to build the four track crossing was placing the main 1,200t Warren truss for the 75m span. “Fortunately there was some unused Network Rail land alongside the mainline tracks where our subcontractor Fairfield Mabey could assemble the bridge,” says Bradshaw. To get it into position needed a 56 hour possession, booked long in advance. “We used multi-axle self- powered transporter units for the move. The truss was jacked at finished height onto trestles on the back of the transporter units and then moved south- wards some 60m. Then one end of the truss was slewed across in a 60m long arc while the south end took a shorter 20m long path” says Bradshaw. Big move: Four multi-axle transporters move the 1,200t Warren truss for the New Cross Gate flyover into position The construction yard embankment area was previ- ously surfaced with a 300mm thick layer of recycled demoli- tion aggregate to improve its load bearing capacity for the move. To prepare the four mainline tracks for the heavy loadings of the bridge and its transporter units, various bespoke level crossing options were consid- ered. But they would have been expensive, not only because a lot would have been needed but they would have had to be Covering up: Temporary fill cover the track during the flyover move Truss: Last minute adjustments tailored to fit irregular track and sleeper spacings. TRACK Instead, a simpler solution was found. By removing the On the new viaducts and in the track construction manager for concrete track slab poured around third rails that provide traction tunnel, the East London Line three years of the project. The it has to be reinforced to handle the power for trains in Network sees the first application of the difference lies in the concrete additional movement created by Rail’s Southern Region and Sonneville boot system of slab surround for the blocks. Mostly this the addition of the membrane. protecting the running rails track. is just mass concrete poured around The boot system is complex to with steel channel sections, it the booted blocks that are carefully install, since each sleeper end is was possible to build up a load For new viaducts and tunnels, positioned by hanging them from independent and must be accurate bearing platform using conven- slab track was installed, using the precisely positioned rails that for rail inclination, gradient, gauge, tional ballast. This meant it the Sonneville system of concrete have been placed inside a basic alignment and more, before fixing was unnecessary to keep the blocks to support either end of concrete trough. But for additional in concrete. It is the first application temporary fill and the existing the sleeper, all embedded in a noise suppression on viaducts, the in the UK. Drivers have already line ballast separate. Any surplus concrete slab. Each independent trough is lined with an additional informally declared the line the would simply form part of the block sits on a neoprene pad inside absorbent membrane and the smoothest they have experienced. railway afterwards. a rubber “boot” which dampens vibrations; and the blocks can be extracted and the boot renewed easily when necessary. Noise “To get the flyover suppression was the key factor on into position needed viaducts particulary as they run through crowded areas of the city, a 56 hour possession. but reduced maintenance was the We used multi- prime reason for the choice in the axle self powered tunnels, where only night-time access is possible. transporter units for “We had two variants of slab, the move” the basic one and in some places the mass spring system,” says Andy Bradshaw, BBCJV BBCJV’s Steve Bradley who was Sound solution: Rubber “boots” under the track damp down vibration