Tamar Road Bridge - Recoating Scheme.

Descriptions

The Tamar Bridge (opened in 1961) forms a vital link across the Tamar estuary between the town of Saltash in Cornwall and the city of Plymouth in Devon and is part of the A38 trunk road network. The crossing is jointly owned by Cornwall Council and Plymouth City Council (the Joint Councils) and operated on behalf of the two authorities by the Tamar Bridge and Torpoint Ferry Joint Committee (TBTF). Funding for the facility is principally provided through a toll charged in the eastbound direction (Saltash to Plymouth), 24 hours a day, 365 days a year. Approximately 16 million vehicles cross the facility annually. In 1999 the bridge underwent a major strengthening and widening project which provided an additional traffic lane (north cantilever), a dedicated pedestrian/cycle path (south cantilever), elimination of a dangerous road junction, improved public transport priority and safer access for toll collectors and maintenance staff. The main deck carries three traffic lanes, which are operated in a tidal fashion to match the dominant traffic demand.The bridge is a conventional suspension bridge with symmetrical geometry, having a main span of 335 metres and side spans of 114 metres, and with anchorage and approach spans the overall length is 642 metres.The towers are constructed from reinforced concrete, and have a height of 73 metres with the deck suspended at half this height. The towers sit on caisson foundations founded on rock.The main suspension cables are 350 mm in diameter and each consists of 31 locked coil wire ropes, with vertical locked coil hangers at 9.1 metre centres. The main cables are splayed at the anchorages and anchored some 17 metres into rock.The suspended structure comprises a stiffening truss that is 5.5 metres deep and composed of welded box sections, and a lightweight steel orthotropic deck composed of 13 mm deck plate stiffened by “U” shaped troughs 6 mm thick and 230 mm deep, spaced at approximately 600 mm centres.TBTF operate a robust inspection and maintenance regime in line with current standards which meet the requirements set out in the Department for Transport Design Manual for Road and Bridges (DMRB), Volume 3 and relevant sections contained therein.Following extensive investigations and the development of an appropriate recoating strategy the Joint Councils wish to appoint a specialist, ICATS registered, contractor to recoat the bridge structure, in accordance with the preferred coating strategy. This will initially involve undertaking relatively small controlled trials, of up to 6 different Highways Agency approved coatings, to determine the optimum performing coating to be applied, where necessary, on the underneath of the bridge structure, below the road deck. Therefore, a key matter to consider and address will be safe and secure access to some particularly difficult areas of the Bridge structure that will need significant recoating.The intention is to let an initial 2 year contract towards the end of this year but, allowing for mobilisation etc.,commencing operationally in early Spring 2015, with an option to extend by up to a further 2 years (one plus one).It should be noted that, although this is an Open Procedure procurement exercise, prospective providers will be required to meet some fairly stringent minimum thresholds concerning financial health and insurance etc. in order to fulfil the requirements of the Invitation to Tender document.Further information on the Tamar Bridge service is available at www.tamarcrossings.org.uk