Rochester Old Bridge principal inspection

Project summary

Rochester’s Grade II listed Old Bridge, built in 1856, requires regular inspection to ensure its continued safe use. Carrying the A2 over the River Medway, the bridge was inspected by specialist surveyors at Up and Under with the support of rope access specialists at CAN Structures. The inspection aimed to identify the presence of corrosion, loose or missing fixings, cracks, impact damage, distortion, deflection or other signs of structural distress.

The background

Built in 1856, the Old Bridge is a Grade II listed structure reconstructed in 1914. Managed by the Rochester Bridge Trust, the cast iron, steel and concrete bridge runs for 150 metres, connecting Rochester and Strood. Carrying the A2 over the tidal River Medway, the bridge requires regular inspection in line with national guidelines to inform maintenance requirements. The principal inspection is being conducted by Up and Under, with specialist access support from sister company CAN Structures. Principal inspections require a within-touching-distance examination of all parts of the bridge structure.

The work is part of a six year contract with the Rochester Bridge Trust to carry out inspections of its assets, with Up and Under completing principal inspections of the New Bridge in October 2024.

The challenges

The historic construction of the Old Bridge makes it challenging to closely inspect the below deck elements and underside of the bridge. Owing to its age and construction, it was not possible to fix or attach any access equipment to the structure. Additionally, the arched trusses of the main bridge and footway loading restrictions meant that it was not possible to use lorry-mounted underbridge access platforms. The fast flowing river and its tidal range of six metres presented difficulties in using river-based work platforms. As a result, a novel access solution was needed to assess these areas.

The bridge extends over a navigable section of the River Medway and sees frequent water traffic throughout the day. It is the primary route between two large towns in this area of Kent and consideration needs to be given to road and foot traffic, as well as water traffic, to ensure the safety of technicians and the public during the work.

The solutions

To overcome these challenges, CAN used its CAN-Beam access system to provide a stable platform beneath the bridge to work from. Rope-access-trained inspectors can more efficiently work from this movable platform, which mitigates the need for temporary scaffolding or directly attached structures that might damage the protected bridge.

To ensure the safety of the public and inspectors through the duration of the works, closures were put in place over the four week delivery period. River users were advised of the works by the navigation authority Peel Ports and signs were in place to indicate which spans were closed to river traffic. Additional closures on the footway over the bridge and deck inspections carried out overnight helped minimise the disruption of road lane closures. The summer period was chosen specifically for the works to reduce potential disruption while the schools were on holiday.

The impact

The findings from the inspection will be used by the Rochester Bridge Trust to inform future maintenance and monitoring of the bridge’s condition. National guidelines require principal inspections to be undertaken every six years to ensure the continued safe use of the bridge. These regular inspections are protecting the historic structure of Rochester’s Old Bridge and providing opportunities for pre-emptive maintenance and upkeep.

The Old Bridge is a historic feature in Rochester’s architecture and the continued maintenance ensures it remains present for many more decades to come.