Project: Breamore Great Bridge
Client & designer: Hampshire County Council
Contractor: Geoffrey Osborne
Built around 1900, Breamore Bridge spans the River Avon in a conservation area and is an excellent example of an early steel lattice girder road bridge with transverse trough decking. This deck had been strengthened in 1980 with reinforced concrete infill. But a 7.5t weight limit was imposed in the late 1990s when an inspection revealed extensive corrosion of the girder bottom flanges and pier support beams.
Limited clearance above the fast flowing river led to the decision to lift out the two 12.6m spans completely, break out the modern concrete repair and transport the spans to a yard for reconstruction. Work was governed by the decision to preserve as much of the original structure as possible. But the trough deck and all four bottom-girder flanges had to be cut out and replaced, the decking with steel specially pressed to replicate the original profile.
The lower sections of most flat and angle diagonal members also had to be cut out and replaced by new material joined in with full depth butt welds.
Project: A6 Cavendish Bridge Refurbishment, Shardlow, Derbyshire
Client: Highways Agency
Designer: Scott Wilson Kirkpatrick
Cost: £700, 000
Cavendish Bridge, built between 1955 and 1957 and now bypassed by the A50, was one of the very first post-tensioned concrete bridges of the post World War II era and the easy option on discovering corrosion would have been to knock it down. In fact its careful repair and restoration could lead the way to the salvaging of similar bridges that are disadvantaged by being out of fashion as well as having insufficient live load capacity, chloride corrosion, substandard parapets, leaking half joints and leaking deck membranes.
Project: Buttington Bridge Strengthening
Client: National Assembly for Wales
Designers: Powys County Council and Parsons Brinckerhoff
Contractor: Alun Griffiths
What began as a simple replacement of the understrength jack arches of the 4.5m sidespans to the 31m wrought iron Buttington Bridge grew into a major project on site when other defects were discovered in the 1872 Grade II listed structure. A three day road closure enabled the side spans to be replaced with heavy duty reinforced concrete precast slabs which were then disguised during one way working with new masonry to replace the original soft sandstone. The decision to take the opportunity to repaint the main arch structure and realign the bolted iron parapet then led to substantial additional work as the true state of the parapet was determined.
Removal of the kerb and road surfacing revealed serious corrosion in the parapet fixings.
The parapet castings were dismantled, carefully blast cleaned, repaired by welding, painted and refixed using heavy duty mountings. This was considered safer than restricting the carriageway width with additional steel barriers.
Project: Kingston Bridge Strengthening and Widening, Kingston-upon-Thames, Surrey
Client: Royal Borough of Kingstonupon-Thames
Principal designer: Symonds Group
Contractor: MJ Gleeson Group
Other firms: Universal Stone
Strengthening of Kingston Bridge was deemed necessary to upgrade the five span masonry arch bridge built in 1828 and its replica widening completed in 1914. But what began as a strengthening operation for the busy crossing of the River Thames grew into a very high quality widening project when it was realised that a temporary crossing needed to keep traffic moving would cost nearly as much as an addition to the permanent structure.
New piled foundations carry precast concrete arches which are lined with brick slips and are almost indistinguishable from the earlier arches. New stone voussoir facings are exact replicas of the structural originals which had to be left in place. Masonry facings to the piers were salvaged and reassembled to make the new upstream face identical to the original.
Project: Caergwrle Packhorse Bridge Repairs
Client: Flintshire County Council
Designer: High-Point Rendel
Contractor: FG Whitley & Sons
Floods in November 2000 swept away some 30m of the parapets and spandrel walls of the 17th century stone footbridge crossing the Alyn between Hope and Caergwrle. The seven arch bridge is a listed Ancient Monument and forms part of a well used footpath.
A temporary walkway was built while the remains of the 56m long bridge were carefully surveyed and old records and photographs examined so the missing structure could be replaced as near as possible to its original state - rather crude random masonry laid in the 1600s by relatively unskilled labourers. Useable stone was recovered from the river channel and supplemented by material from a local building that was being demolished. Three of the original arches which had been buried or silted up were cleaned out, raising capacity from 41m 3/sto 65m 3/s.
Project: Restoration of the V2 Vivian Incline, Padarn County Park, Gwynedd
Client: National Museums & Galleries of Wales
Designer: Posford Duvivier
Contractor: Watkin Jones & Sons
Other firms: Gwynedd Archaeological Trust
For about 150 years self acting inclined planes were the primary means of transporting cut slate from mountainside quarries in the Llanberis region down to sea level for distribution to customers by ship or rail. V2 Vivian Incline is typical of these ingenious devices, the remains of which can be seen thoughout the area. It had lain derelict and accumulating a cover of scree since 1936.
The restoration project involved a detailed archaeological and engineering investigation of the site followed by a careful reinstatement using a mix of recovered and replica components.
It has been put back in working order as near as possible to its original state except that the lack of a steady supply of slate as motive power has necessitated an electric motor to simulate the original movement of the funicular.