Decision details

Following a routine inspection, a significant defect was found relating to the fixed bearing on Commercial Street Bridge. It was advised that this should be rectified by Q2 of 2024 to ensure the bridge remains safe.

SYMCA appointed Balfour Beatty through the SCAPE framework under a design and build contract, to undertake the repair. They subsequently appointed Mott MacDonald to undertake the design as a subcontractor.

Mott MacDonald considered a range of design options for the remedial work, each with a range of benefits, risks and costs associated and presented these to SYMCA who endorsed a preferred option to strengthen the bridge diaphragm with the additional of steel plates bolted through, with remedial concrete repairs where required.

Balfour Beatty priced the works in accordance with the SCAPE Framework and approval was requested to appoint Balfour Beatty to progress to implementation of the preferred scheme at a cost of circa £375,000

Option A - Approve the appointment of Balfour Beatty to undertake rectification works on the defect in the diaphragm above the fixed bearing on the Commercial Street Bridge through the SCAPE framework at a cost of £374,214.90.

Option A - Repair and strengthen the diaphragm with steel plates. This was the chosen and lowest costed option at between £500,000 and £600,000.

Option B - Repair and strengthen the diaphragm with increased reinforcement and concrete repairs, but also increasing the size of the diaphragm. This could impact on the operational tram network and has a higher cost than Option 1 at around £575,000 to £675,000 and was therefore discounted as it would take longer to execute and cost more, as well as reducing accessibility around the rear of the diaphragm for future inspections.

Option C - Replace all the bearings on the affected diaphragm of the structure. This is a more extensive operation with an estimated cost of £2.5M to £3M. As the bearings, with the exception of the defective fixing around the top of the fixed bearing, appear to be in a generally good condition, this option was discounted.