Engineering analysis and design software
Bridge design and engineering

Case Study

Twin Sails Bridge

  • World's first triangular-leaf lifting bridge

Twin Sails Bridge open to shipping. Image: Jeff Owen

Twin Sails Bridge is a novel steel bascule road bridge that spans a navigation channel linking Holes bay with Poole Harbour in the UK. The bridge provides a second road link connecting Poole town centre with Hamworthy - a site of planned redevelopment. Ramboll worked closely with architect Wilkinson Eyre and mechanical engineer Bennett Associates to develop the bridge concept and used LUSAS Bridge analysis software to assist with its design of the crossing.


Twin Sails Bridge is the world’s first triangular-leaf lifting bridge and was constructed by HOCHTIEF (UK) Construction Ltd. The bridge has an overall length of approximately 139m which includes a central opening span of 23.4m between main bearings and two approach spans of approximately 27m. Its 10.8m wide carriageway incorporates two vehicular lanes segregated from two cycle lanes. In addition, two 2.5m wide footways cantilever either side of the bridge. The twin sail-like structures forming the lifting leaves weigh 65 tonnes each. Each leaf is connected to pivot bearings at one of the main piers and rests on a single bearing near the apex of the triangle on the other main pier. To permit the unrestricted passage of shipping the lift spans are pivoted through 88 degrees by two hydraulic rams to provide a clear channel width of 19m between the faces of fenders of the main piers when in the open position.

The bridge opened to traffic on 4th April 2012 and operates alongside the existing Poole Bridge, with one of the bridges always open for vehicular traffic when the other is open for shipping.

Twin Sails Bridge closed to shipping. Image: Jeff Owen

When closed to shipping the bridge looks quite unassuming.


Twin Sails Bridge lifting in progress. Image: Tanya Hart

Twin Sails Bridge fully raised. Image: Alex Martin

Raising the pair of 65 tonne lifting leaves takes 
around two minutes
When fully raised the bridge creates the impression 
of two passing yacht sails



Other LUSAS Bridge case studies:


Software Information

  Bridge / Bridge plus
green_arrow.gif (94 bytes) Software overview
green_arrow.gif (94 bytes) Modelling in general
green_arrow.gif (94 bytes) Advanced elements, materials and solvers
green_arrow.gif (94 bytes) Load types and combinations
green_arrow.gif (94 bytes) Staged construction modelling
green_arrow.gif (94 bytes) Geotechnical / Soil-structure modelling
green_arrow.gif (94 bytes) Analysis and design
green_arrow.gif (94 bytes) Design code facilities
green_arrow.gif (94 bytes) Viewing results
green_arrow.gif (94 bytes) Software customisation

  Bridge LT
green_arrow.gif (94 bytes) Software overview

  Choosing Software
green_arrow.gif (94 bytes) Software products
green_arrow.gif (94 bytes) LUSAS Bridge LT
green_arrow.gif (94 bytes) LUSAS Bridge
green_arrow.gif (94 bytes) LUSAS Bridge Plus
green_arrow.gif (94 bytes) Software selection
green_arrow.gif (94 bytes) Software options

green_arrow.gif (94 bytes) Videos
green_arrow.gif (94 bytes) Case Studies

  Additional Information
green_arrow.gif (94 bytes) Linear and nonlinear buckling analysis
green_arrow.gif (94 bytes) Curved girder analysis
green_arrow.gif (94 bytes) Integral or jointless bridges
green_arrow.gif (94 bytes) Post-tensioning
green_arrow.gif (94 bytes) Concrete modelling
green_arrow.gif (94 bytes) Interactive Modal Dynamics
green_arrow.gif (94 bytes) LUSAS Programmable Interface (LPI)

  Example applications
green_arrow.gif (94 bytes) Footbridge design
green_arrow.gif (94 bytes) Rail solutions
green_arrow.gif (94 bytes) Soil-Structure Interaction Modelling

  General information
green_arrow.gif (94 bytes) Hardware specification
green_arrow.gif (94 bytes) Licencing and Networking options
green_arrow.gif (94 bytes) Software prices
green_arrow.gif (94 bytes) Documentation
green_arrow.gif (94 bytes) Links page

Request information


innovative | flexible | trusted

LUSAS is a trademark and trading name of Finite Element Analysis Ltd. Copyright 1982 - 2019. Privacy policy. 
Any modelling and analysis capabilities described on this page are dependent upon the LUSAS software product and version in use. Last modified: June 03, 2019.