Bridge to the Isle of Wight

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Group Design Project
The design of a road bridge to the Isle of Wight, including a feasability assessment, detailed design and economic appraisal
Group Members
Dinuk Weerasekera, James Warbey, Prabin Limbu, Rishi Patel, Said Al-Dhaybes, Thomas Rackham

Supervisors
Dr. David Brown, Dr. Simon Clubley

Supporters
Isle of Wight Prolink Group

Currently, there is no fixed link between the Isle of Wight and the south of England. This limits the economic growth in the area and severely hinders the free movement between the mainland and the island. This project designed a dual carriageway road bridge, with a cycle and pedestrian path, which spans across the Solent.

The project started with analysing potential sites on both the mainland and the island. This involved desk studies, site visits and consultation with a transport planner with in depth knowledge of a possible fixed link in the area. Multiple aspects were considered, including environmental issues, shipping areas and the population density across the area, Lepe and Gurnard were selected as the most suitable landing points for the bridge.

The design process began by producing numerous physical models which were refined to achieve the best aesthetic, and the most striking structure. It was important to make each component as slender as possible, so a multi-span cable stay bridge was deemed to be the most appropriate solution. LUSAS bridge plus was used to model the main spans. This was an iterative process of making changes to each part of the bridge to produce an efficient structure.
The bridge is designed with a concrete and steel composite multi-cellular deck. The shape of the deck allows for reduced wind loadings without the presence of vortex induced vibrations; as demonstrated by extensive wind tunnel testing. The deck designed allows for modular construction across the entire length of the main span. This allows for quick fabrication, and therefore reduced costs.

LUSAS bridge plus was also used to develop a construction sequence of the bridge. Each step of the balanced cantilever method was analysed in detail. This resulted in further refining of the design of the structure to improve the competence of the bridge.

The final bridge design consists of three towers that support the deck, via connections of two planes of 165 mm cables, to form two main spans of 500 m. The height of the bridge, from the sea bed, is equal to 214 m. Including approach viaducts, the bridge is the longest three towered cable stay bridge in the world.

The bridge not only provides a permanent crossing to the mainland, but also significantly reduces the time taken for the majority of the popular journeys. The suggested toll prices from an economical evaluation of the bridge illustrates the reduction in cost compared to the current ferry prices.

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