Semaphore Bridge
Refurbishment of a historic steel bridge supported by cylindrical piles, including structural steel repairs, bearing replacements, and installation of a new deck finish and balustrade. The project upgraded key components while preserving the bridge’s historic integrity.
- Complex tidal site
- HSE Inspected site
- Key asset restored
Overview
Refurbishment of a historic traffic-way bridge at a local MOD site, delivered as principal contractor. Works included full site mobilisation and structural restoration, application of a new multi-coat marine paint system to all steelwork, installation of a new galvanised structural support deck with GRP finish, new balustrade edge protection, replacement roller pin bearings, and associated structural repairs throughout.
The Challenge
Due to the nature of this project, several challenges were encountered, the most significant being tidal conditions. Rising tides periodically submerged the structure, impacting access and progress and requiring careful planning and coordination to complete the works safely and efficiently.
The late-1890s bridge is supported by two main structural girder beams recessed within the granite wall, bearing on steel roller pins. We were tasked with developing a safe and effective design and method of works to replace the existing roller bearings, while maintaining the structural integrity of the bridge throughout the process.
Solution
These conditions impacted every project milestone, with scaffolding erected using a workboat and, at times, wading access. Once the scaffold was in place, structural repairs and UHP (ultra-high-pressure) water blasting were completed, followed by the application of protective paint systems carefully timed to accommodate rising tides.
To overcome the challenges associated with replacing the bridge’s roller bearings, our design team developed a solution using a stainless steel alternative. Given the condition of the existing bearings, this approach was selected to significantly extend the lifespan of the client’s asset. Installation of the new roller bearings and associated components was complex, but was successfully achieved using hydraulic jacks and temporary support systems, ensuring the works were carried out safely and effectively.
All works were completed within a busy operational environment, requiring careful management of traffic, tidal conditions, and subcontractors on a constrained site with limited access. We are proud of the final outcome and thank KBS Maritime for trusting us with the refurbishment of this historic asset.
Working with MTECH, particularly Martin, has been a very smooth experience. Any questions raised—whether in face-to-face meetings or via email—are always answered promptly and professionally. When site visits to Portico were required, Martin was extremely helpful in arranging gate access and ensuring everyone had the correct security clearance and completed the training video.
The refurbishment itself was carried out to a high standard, and site visits were always welcomed. The end user is very pleased with the addition of the new hydraulics, which significantly reduces manual handling. Overall, working with MTECH has been an excellent experience.
KBS Maritime
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