Murphy Eltel Joint Venture achieved a key milestone on National Grid’s Richborough OHL Connection project this week, installing two 110-metre-long temporary bridges across the River Stour.
The bridges are required to unlock the final land sections of the 400Kv overhead line route and allow for construction of the remaining nine, 60-metre-high, lattice towers.
The bridges, which weigh 227 tonnes and were fabricated by Mabey Bridge, were delivered to site in 22 loads and pre-assembled within a small footprint at each site.
Murphy Eltel JV project director Andy Ingram said: “There has been a lot of collaborative work behind the scenes over the last six months here to achieve this milestone. From obtaining the third-party consents within the constraints of the Development Consent Order to the detailed design and fabrication of both structures there has been strong teamwork across the joint venture and client team.”
Each bridge was installed using different methods; the first (DX49) was lifted in to place by a 1000 tonne mobile crane and the second (DX32) was launched into position as twin overhead live 132kv conductors obstructed a lift.
The launching of the second crossing took eight hours with a further four days required for jacking the bridge to its final position. Both structures were designed to sit four and a half metres above the water providing uninterrupted use of the River Stour to the public.
The project team worked closely with Murphy’s in-house engineering team, Murphy Applied Engineering (MAP), from inception stage to develop the most economical and efficient design.
The installation of the bridges marks one of the final significant milestones for the Richborough OHL Connection project as it moves closer to energisation of the 400Kv line in late November.