Design Development of the Marine Foundations for the Forth Replacement Crossing

This paper describes the collaborative approach used to develop the design and construction proposals of the marine foundations for the Forth Replacement Crossing. The three authors come from the public client, the technical advisor, and the design and build team therefore provide a different perspective on this process to produce a successful design. The programme of construction trials used to demonstrate the suitability of the construction proposals are described together with the design approach used to address the various challenges inherent in constructing marine foundations within the Firth of Forth.

The Forth Replacement Crossing is the largest infrastructure project in Scotland for a generation and the new cable stayed bridge will form a new 21^st century landmark to set alongside the existing 20^th century road bridge and the iconic 19^th century rail bridge. The design and construction of the marine foundations for the main crossing is one of the key challenges of this project. The 2.6 km crossing, of which 2 km is cable stayed bridge, passes over the Firth of Forth which is one of the busiest stretches of water in the UK with vessels servicing the ports and oil based industries further upstream. This paper focuses on the process of developing the foundation design from initial concept through production of the specimen design to the final adopted design approach based around a significant dialogue process between the Employer’s and bidding contractor’s teams.