Subsea 7 Plant Access Bridge, Wick, Scotland

Challenge

Subsea 7 is a global leader in the delivery of offshore projects and services for the evolving energy industry. The company’s fabrication plant near Wick, Caithness in North East Scotland, runs 7.8km inland, covering a total area in excess of 300,000m². It includes a sheltered bay from where the company launches its pipeline bundles, which include structures, valves, pipelines and controls necessary to operate an oil and gas field and are fabricated onshore as single systems, before being towed offshore. Some of these systems can measure over 7km in length and weigh several thousand tonnes. Until recently an ageing and run-down bridge had been the only river crossing which allowed access to the landward end of site to allow the bundles to be fabricated. Now in urgent need of replacement, the new structure had to be capable of carrying loads of up to 400 tonnes.

Solution

An Atlas™ bridge was specified as the most viable solution to replace the old bridge, after Subsea 7 held various meetings with Mabey Bridge Site Advisors to discuss different options. Atlas™ was chosen, partly because of its reputation for robustness and reliability, but also Mabey Bridge’s experience in installing bridges in particularly challenging locations. Subsea 7 had previously used Mabey Bridge products.

Atlas™ is a lightweight pre-fabricated steel, modular bridging system that combines the benefits of a unique-engineered, modular deck with the simplicity of plate girder construction.

The new bridge design comprised a 27m long, 5.25m wide carriageway, with a load carrying capacity of 400 tonnes. The bridge was manufactured entirely off-site, then transported and installed easily by Mabey Bridge Engineers, employing a crane-assisted launch system. This ensured the project was delivered more quickly, safely and efficiently.

Result

The new Atlas™ bridge at the Subsea 7 plant not only provides a functional and aesthetically pleasing solution – it now enables a much improved access route to the site as well as accommodating the ever-increasing demands of subsea pipeline projects in the North Sea.