Kexby Old Bridge

Overview

Kexby Old Bridge is a three-span masonry arch bridge listed at Grade II* and also a designated ancient monument. The bridge was built in 1650 and until the 1970’s carried the A1079 Hull to York trunk road. Mason Clark Associates (MCA) were instructed by East Riding of Yorkshire Council (ERYC) to conduct a principal inspection and assessment, then provide effective suggestions for the strengthening of the bridge.

Tasks / challenges

The age and listing of the structure, the presence of roosting bats, protected River Lamprey in the River Derwent and the designation of the surrounding land as a SSSI all complicated the scheme and required us to liaise extensively with Natural England (NE), Historic England (HE) and the Environment Agency (EA). Other challenges faced, included:

• Working over water – Northern Divers provided a pontoon and scaffolding to allow the inspection to be undertaken along with a safety diver for emergencies.
• Working on an unsafe structure – due to the damaged to the underside of the northern arch, the bridge was shut to the public and further inspections and investigations were limited to foot traffic and small hand tools / plant. Monitoring of the structure was undertaken on a regular basis to ensure no further movement occurred.

MCA's bridge engineers provided a design which was agreed by all parties and produced all tender documents on behalf of ERYC, they also undertook site supervision and contract administration duties during the contract.

MCA carried out a load capacity assessment and designed the Phase 1 scheme to ensure the bridge does not collapse. Phase 1 included the design of steel arch rings to stabilise the stonework, which involved detailed discussions and approval from EA and English Heritage (EH).

Results

The principal inspection undertaken by MCA highlighted significant deterioration of one arch on the upstream elevation, likely as a result of impact damage from river debris during one of the frequent flooding events on the River Derwent. The extent of the damage was deemed serious and an immediate closure of the bridge was implemented, which due to the adjacent Kexby New Bridge, did not cause significant disruption to road users. A strengthening scheme was then developed to stabilise the damaged arch.

Contractor Jackson Civil Engineering completed the works on time and budget despite rising river levels causing delays during the project. This first phase of the works has strengthened the bridge sufficiently to allow a larger scheme to be developed to create a long-term solution for the bridge.