Case Study: WSP builds 50-story Principal Tower on a tiny footprint while protecting Victorian-era rail tunnels with Bentley (PLAXIS and RAM Concept)

WSP Overcomes a Small Footprint to Construct 50-story Principal Tower, Protecting Victorian-era Rail Tunnels

WSP, a global engineering and consultancy firm, was commissioned to design the 50-story Principal Tower on a constrained footprint beside Liverpool Street station and Victorian-era masonry rail tunnels. Their challenge was to deliver the owner’s architectural vision while building two basements and installing piles as close as 50 mm to live, vibration-producing tunnels, secure Network Rail approval, and use top-down construction to fit the tight site—tasks that required advanced analysis with Bentley products PLAXIS and RAM Concept.

Using Bentley’s PLAXIS and RAM Concept, WSP modeled 2D/3D soil movement, validated a top-down approach with the ground-floor slab as a horizontal prop, optimized temporary miniature piles and a steel piling deck, and modeled elastomeric bearings for vibration and acoustic isolation. The Bentley-enabled design won Network Rail approval, reduced reinforcement and support materials by 60% (about 17 tonnes), lowered temporary works, cut material and labor costs, and enabled a more efficient construction sequence that protected the tunnels and accelerated returns.

WSP

Nello Petriolli

Associate Director and Project Engineer