On the Bridge to Nowhere, Glasgow, Scotland
In Glasgow, the infamous Bridge to Nowhere was supposed to connect two lively communities in Charing Cross and Anderston. However, the project that started in the 70s wasn’t completed until 2013. The finished bridge, the Anderston Footbridge, connects once-exiled communities to the city centre. Raynesway Construction, a Balfour Beatty company, contracted TGS to design and install permanent bearing piles for the bridge’s pier foundations.
TGS’ project scope involved designing and installing the permanent bearing piles to support the bridge’s pier foundations. The narrow and restricted site was bounded by imposing walls from Waterloo Street to the north and a multistorey car park to the south. TGS’s work included installing 12 vertical bearing piles with loads of up to 800 kN in both tension and compression. A sacrificial preliminary test pile installation was also carried out just outside the working area. We had to overcome numerous challenges, including the sensitivity of nearby structures to vibration. Logistical issues concerned placing the single length steel reinforcement into the top of the pile.
TGS installed the 220/190 mm permanently cased drilled piles 30 m below ground. We used a Klemm 702 minipiling rig, with a remote power pack located about 50 m from the rig and connected via umbilical-hydraulic hoses. The permanent casings were installed to the top of the rock using an overburden drilling system, before using a down-the-hole hammer to form the rock socket. All piles were grouted using a tremme immediately after drilling and inserting a full length central reinforcing bar. The pile heads were reinforced with a universal column to carry the anticipated lateral loads safely. This element was placed using lifting equipment on the upper floors of the nearby car park.