The project is part of a massive infrastructure investment in Scotland’s transport network.
The construction work includes almost 8 km of new dual-lane motorway and hard shoulders between Stepps and Mollinsburn; 2.7 km of the existing A80 road upgraded to three-lane motorway between Mollinsburn and Auchenkilns; and finally, almost 7.3km of the existing A80 upgraded to dual-lane motorway between Auchenkilns to Haggs with hard shoulders and climbing lanes.
Work on the M80 project requires extensive demolition and reconstruction on existing structures along the route, including the widening of existing bridges and construction of new ones. This is complicated by the fact that, as a vital arterial route across Scotland’s most densely populated region, the road must remain in use throughout the construction period. Harsco Infrastructure is playing a vital role providing specialist access, formwork and falsework systems for this contract.
Concrete and Civil Engineering specialist T-Mac Construction, is carrying out all the ‘on-line’ work – that is, constructing new and extensions too, existing bridge structures on the main route itself, in total about 16 structures.
T-Mac was awarded the subcontract via a traditional competitive tender process and part of its winning bid was a methodology developed in partnership with Harsco Infrastructure, to minimise disruption on the A80 by closing off the hard shoulder and slow lane.
The work requires a varied approach to access and formwork. This not only entails considerable health and safety risk, but also imposes significant logistical and design problems. The safety challenges have been met by using Harsco Infrastructure’s equipment to create an enclosed working area to isolate the workforce from the traffic, but this in itself presents challenges as space within the structure is limited.
“We are utilising a variety of systems from our portfolio to offer workable and time saving solutions” says David Hancock, Sales Manager for Harsco Infrastructure.
CUPLOK®and MkII Soldier Falsework components are used to create a safe hydro-demolition deck under each bridge which serves as a working platform, as well as access for steel-fixing operatives before the introduction of falsework for the new in-situ concrete.
“Essentially, the work involves hydro-demolition to break out existing concrete to expose the steel reinforcement before erecting formwork, stitching in the new rebar and casting the bridge extensions” explains T-Mac Managing Director Mike Traynor.
The newly-widened carriageways, the existing bridge cantilevers and RC bridge beams are partially demolished and new ones cast. The bridge cantilevers are then extended at either side of the decks and new parapets formed. The central sections of the carriageway are also being strengthened by casting new in-situ concrete beams and in-situ soffits.
Examples of these works are on the Dullatur, Forrest Road and Old Inns Bridge structures, where T-Mac achieved the HMC Monthly Health and Safety Award as a direct result of planning hand in hand with Harsco Infrastructure’s Design department, equipment and resources.
“We planned this project for months in conjunction with the main contractor and sub contractor to ensure the correct solutions for each individual structure” comments Mr Hancock. “This included the use of our MULTIFORM®parapet brackets, for on-line as well as off-line bridge structures”.
T-Mac also used the TOPEC®soffit panel system supported by modular aluminium GASS®legs for the soffit stages on the existing structures reinstatement, due to extremely restricted work space on these structures. Mr Hancock explains “TOPEC®allows the contractor to fit large soffit areas of completed falsework by simply lifting the aluminium panels into place because they are lightweight. Traditional falsework solutions would have required prolonged work in a confined space for both erection and striking the system”.
The original plan was to complete all the extension work on the southern (i.e. west-bound) carriageway, then switch to the northern (east-bound) side and then finally travel back to Haggs, carrying out bridge strengthening work along the central reserve. However, the need to adapt to unforeseen circumstances has resulted in a flexible working regime and the methodology has altered slightly.
“This project has demanded the highest possible level of planning, engineering, design and logistics. In January 2010 we had the worst winter weather for several years, with record low temperatures and heavy snow” he adds, “but although the project suffered delays, the contractors have managed to adapt to the conditions and the final completion date has not been affected. The meticulous planning has paid off.”
Construction work is due for completion in early 2011.