Procurement and construction
The procurement exercise for the project was one of the biggest ever undertaken in Scotland. Various methods of funding and constructing the project were considered before Ministers decided the most suitable procurement route was a traditional “design and build” contract for a fixed price and funded from existing capital budgets.
After around a year of complex, technical competitive dialogue with the potential bidders for the project, the Principal Contract to build the new bridge and connecting roads was awarded in April 2011 to the Forth Crossing Bridge Constructors (FCBC) consortium. The successful tender price of £790m was significantly below the original estimated price range of £900 to £1.2 billion. FCBC is a consortium of Hochtief from Germany, American Bridge from Pittsburgh, USA, Dragados from Spain and Morrison Construction from Scotland.
On the south side, the contract to upgrade M9 Junction 1a at Kirkliston was awarded in July 2011 to a consortium between Irish contractors John Sisk and Roadbridge.
The contractors began mobilising in the summer of 2011 – establishing compounds in Echline, Kirkliston, Rosyth docks and Inverkeithing. The main compound for FCBC and Transport Scotland – which has an “Employers Delivery Team” co-located to oversea the contractor – was established on the site of an old Ministry of Defence fuel bunker near Ferrytoll. The three-storey building is made of temporary modular units which were previously the main office for the London Olympics construction site.
The works kicked off in earnest on all fronts in the late Summer and Autumn of 2011. Particularly noteworthy aspects of work included the blasting of Beamer Rock to lower the surface ready for the construction of the central tower.
Also, in May 2012, the arrival of massive steel caissons certainly got the public’s attention as they made their way slowly up the Firth of Forth and under the Forth Bridge and Forth Road Bridge.
2012 was the year of the foundations, when the caissons (and cofferdam sections for the Central Tower) were carefully located using minute GPS positioning to allow work to begin on the marine foundations for the towers and viaduct piers.
They were then sunk to the sea bed, where teams working from barges excavated and cleaned the bed rock. Over 28,000m3 of underwater concrete was poured to form a concrete plug laying solid foundations for each of the three towers. Temporary caisson sections were then made watertight and the water pumped out to create a dry environment for the teams to begin work on the towers themselves from up to 14 metres below the waterline.
The handover to the tower construction teams was completed on each of the three main towers during July, August and September. This significant milestone saw the move from working in the wet to working in the dry and ensured that 2013 was the year of the towers.
Meanwhile, on dry land, the upgraded M90 in Fife and M9 Junction 1a at the southern end of the entire scheme were both completed in the Winter of 2012/13. Both contracts included the introduction of Intelligent Transport Systems (including gantries managing congestion via variable mandatory speed limits and use of the hard shoulder for buses).
The southern bridge approach viaduct started to take shape in 2013, with the first deck sections being launched over piers to where they would eventually meet the deck sections spanning out from the South Tower. Also largely invisible to the public was the preparation for the South Queensferry Junction and connecting roads, which are largely in cuttings and behind noise bunds. This is an example of the mitigation measures that were implemented to minimise the visual and noise impact of the new roads.