44 | the rail engineer | february 2013
(Top) Blackfriars Bridge. (Bottom) Main cavern in Buenos Aires.
Here, however, application could be discontinuous with the untreated areas between the coated areas being sprayed at a time more convenient to other trades. In total 20,000m² of Integritank HF was successfully installed in the two caverns of Buenos Aires Metro Line B. Both the contractor’s requirement for rapid installation to meet a short programme and the client’s for a high degree of water tightness were met.
Blackfriars Bridge Back in the UK, Stirling Lloyd’s bridge deck waterproofing systems have been used by VolkerLaser on the second phase of a £3 million refurbishment contract now nearing completion at London’s Blackfriars Bridge. The 125 year old landmark wrought iron bridge was refurbished as part of the
bridges & tunnels Thameslink programme to give greater rail capacity through the centre of London. The works, carried out in two phases, consisted of applying some 10,000m² of Eliminator spray waterproofing to the largely steel, with concrete elements, substrate and 1,000m² of Hytec sheet waterproofing to the end abutments. VolkerLaser overlayed 4,000m² of the waterproofing with 900 tonnes of Laserphalt high modulus mastic asphalt, with the remaining area being covered in ballast. The company also installed 50 metres of bespoke expansion joints and applied 25,000 metres of Stirling Lloyd’s Metaset Flex Sealant to joint gaps in the deck plate. Due to adverse weather conditions, VolkerLaser designed and erected bespoke tenting to cover the works and operated around the clock to ensure that each stage of the programme was completed on schedule and achieved the client’s key performance indicators. The scheme also provided another excellent rail bridge showcase for Stirling Lloyds’s waterproofing capability and, as Andrew Welsh, VolkerLaser’s associate director said: “Blackfriars Bridge is one of London’s most congested sites where rigid timescales and health, safety and environmental standards are of paramount importance.”
Londonderry to Coleraine rail track In Northern Ireland, Londonderry’s status as the UK’s 2013 City of Culture has led to improvements in transport infrastructure to accommodate increased visitor numbers. This has included major engineering works on the main line between Londonderry and Coleraine with the track closed until April this year. The work is the first phase of a £75 million upgrade to the track and represents a significant investment by Northern Ireland Railways. It includes a full relay of the track system between Coleraine and Castlerock and between Eglinton and Londonderry and it is on a number of bridges close to the Coleraine section that Stirling Lloyd’s approved bridge deck waterproofing systems have been used. Four bridge structures have been treated in total. Two road-over-rail structures have seen the installation of Stirling Lloyd’s spray applied ‘tightly-bonded’ Eliminator system, with captive blasting of the concrete substrate used to prepare the deck ahead of the application of a coat of PAR1 Primer, membrane and Tack Coat No.2, the latter being used to enhance the strong bond between the membrane and the subsequent 120mm of surfacing. Two separate rail bridges have been waterproofed using Stirling Lloyd’s ‘looselaid’ Hytec system, a flexible polypropylene sheet membrane offering exceptional mechanical properties. Hytec, designed especially for fast track rail possession where deck and climate conditions are uncertain, was the ideal choice for these Coleraine rail bridges. These three examples show the variation of waterproofing challenges faced by structures engineers, and the lengths that they have to go to to keep water where it belongs - not on the railway.
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