Carriageway resurfacing works

Tender description

Resurfacing of the Main Deck of the Tamar Bridge, including the north and south cantilever lanes. The successfully appointed contractor will also be required to safely remove the existing installed series of illuminated lane studs and ensure resurfacing work is completed to the agreed programme, to allow for prompt installation of the replacement studs by the separately appointed supplier, as a key part of the overall resurfacing project. There is also the potential scope to include ancillary expansion joint replacement and resurfacing of the Toll Plaza Area. The value of the works is estimated to within the range of GBP 4.5 million to GBP 5.3 million. The work is anticipated to take place over a period of up to 6 months, anticipated to commence from April 2021. The resurfacing overall is concerned with implementing Stage 2 of the current resurfacing strategy and follows on from the resurfacing Stage 1 of the Plymouth side span in 2011. The stage 1 works just replaced the worst section that had failed prematurely, due to onerous loading conditions. Stage 2 of the resurfacing strategy, which includes the main deck centre span and the Saltash side span and north and south cantilever lanes, was based on a policy of lifetime maximisation of the existing surfacing system until such a point when noticeable and problematic degradation commenced. At the time it was anticipated that the remaining areas would achieve their anticipated design life span in excess of 12 years and at the then anticipated levels of degradation was expected to last for another 3-7 years (2014-2018). It is now the point where the maximum life has been extracted from the remaining surfacing and replacement is required, commencing in Spring 2021. Key constraints: • The bridge must remain open to vehicular traffic with a minimum of one lane in each direction throughout the entire duration of these proposed works and two lanes in one direction and one lane in the other at specified peak times. • The maximum thickness of the proposed surfacing system shall not exceed 55 mm (nominal) and the minimum thickness shall not be less than 40 mm (nominal) as part of the requirements for deflection control and wheel-load distribution into the structure. Although 55 mm depth has already been used successfully on the Plymouth side there is a considerably more significant structural loading implication if it is proposed to be used over the full length of main span and the Saltash side. Preferred solutions will therefore minimise the depth as far as possible to the lower end of the permissible 40 mm – 55 mm range. Preferred solutions will also consider variance of the proposed thicknesses between the main deck and the cantilever lanes. The cantilever lanes experience lower traffic levels and preferred solutions will be at the lowest end of the thickness range. The North and South cantilevers shall have the same proposed surfacing thickness. • Localised tapering of the edges of the surfacing along kerb lines and at expansion joints will be necessary for proposed systems exceeding 40 mm nominal thickness. (This was successfully achieved on the 2011 Plymouth side resurfacing and is possible). Anticipated provisional solutions: The following systems are expected to be the most likely to be suitable as the choice for the final proposed system. • approved sprayed methyl methacrylate waterproofing system (2 layer) plus; • (up to) a maximum of 55 mm ‘Gussasphalt’ type surfacing (as applied on Plymouth sidespans), or similar equivalent; • or 40 mm Polymer modified mastic asphalt; • or 40 mm Mastic asphalt (notionally as per the current 38 mm system but with an additional 2 mm depth to compensate for the removal of the original nominal 2 mm bituminous waterproofing); • other surfacing system materials may be considered provided they can be shown to be equivalent to the above and compatible with the other requirements of this document; • the Toll Plaza surfacing system will be different and the outline specification will be a subject for discussion in dialogue. The outline specifications for discussion in dialogue will all be based on a design life of 20 years for the surfacing system. Tamar Crossings project team intend for this to result in a service life of 20 years subject to the assumptions of the design life (e.g. traffic effects) not being exceeded. The appointed surfacing contractor will be responsible for ensuring that all material supply and installation is compliant with final specifications. It is envisaged that the client will seek to develop and enhance the agreed specification and scope of works, in collaboration with a likely maximum of 3 contractors, to be selected to discuss practical possibilities and options, through a formal competitive dialogue procurement process, to arrive at an optimum working solution for the most suitable surfacing application of the somewhat limited known options. over an agreed period of time. Please note: a detailed contractor briefing document has been prepared and access to that, to further electronic information concerning this project, and to the pre- qualifying questionnaire documentation can only be gained via the Supplyingthesouthwest.org.uk portal, wherein this project has the reference DN422865. All formal communications or queries regarding this opportunity, must only be accessed or made via the supplyingthesouthwest.org.uk portal under Project Reference DN422865.