ICE London Civil Engineering Awards 2013
Bond Street Station Upgrade Project
Principal Contractor (Design & Build): Costain Laing O'Rourke Joint Venture
Client: London Underground
Specialist Trade Contractor: Abbey Pynford Foundation Systems Ltd
Designer: Halcrow Atkins Joint Venture
Specialist Demolition Contractor: Expanded Demolition
The Bond Street Station Upgrade will provide a new entrance to this key interchange in the heart of London’s West End, together with much enhanced capacity and step free access to all platforms. This innovative project involves a new reinforced concrete ticket hall structure constructed below a 1770 Grade 2 listed building, achieved with minimal disruption to the fabric of the building above street level. The new ticket hall, twice the depth of the original basement, was constructed using the “Pynford” stooling technique by specialist contractor Abbey Pynford. This enables a top down construction, whereby the original load path throughout the heritage structure is passed to a heavily reinforced slab.Designed to minimise movement and to preserve the original heritage features, this slab was temporarily supported on numerous temporary props until the permanent supports were complete. The Tanzanian High Commission shares a party wall, so it was vital that minimal disturbance was caused to the operations of the commission and in particular the visa office located in their basement.
The new ticket hall structure is supported on mini piles constructed within the basement. These include 450mm diameter, 18 meter deep plunge piles which, due to space restraints, temporary propping requirements and high magnitude horizontal loads, required a unique solution based on a rock socket design. This incorporated steel sections installed using a high tensile strength 140N/mm2 concrete after all of the 32 piles were complete. Due to varying site ground conditions the design required over 150 piles in an area less than 150m2. The traditional underpinning solution supporting the foundations of the High Commission party wall was replaced by two rows of mini-piled walls, propped by a piled RC slab which became suspended as the work progressed. The integrity of this horizontal propping system was adjusted and maintained during demolition and excavation of the adjoining structure. The new basement slab is founded 3 m below that of the High Commission and designed to cope with effects of constructing a deeper basement and 2 large diameter shafts, 28 m deep below basement slab to the south.
On the south side of the site, and facing Oxford Street, a former bank building built in the 1960’s was demolished to provide access to the shafts and tunnels which will form the new passages and escalator shaft providing improved access to the platforms. The extremely restricted city centre site adds to the complexity of the project. Challenging logistics dictated by the enabling legislation require all deliveries routed away from Oxford Street to enter site through our single Marylebone Lane gate. Regular consultation throughout the construction period with high profile businesses and other organisations inform and reassure them that their interests are being addressed. This has been very successful and has resulted in a Silver Award by the Considerate Constructor’s scheme. An open book relationship with the client and a directly employed and flexible workforce, which is verified on a daily basis by the Aurora system, is a key contributor to provide value for money.
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