Main Line Rail Crossing Bridge Refurbishment

A complex project to improve the A49 Woofferton skew road bridge over the Hereford to Shrewsbury main line rail link saves costs with Tensar Wall System.

In a complex project to improve the A49 Woofferton skew road bridge over the Hereford to Shrewsbury main line rail link, the contractors Geoffrey Osborne Ltd.

used Tensar International's Tensar Wall System as retaining walls to extend and complete the bridge abutments.

Rob Walsh, Site Manager during the project, commented: "Using the Tensar Walling System saved us around £50,000 in materials and labour costs, compared with installing a conventional concrete retaining wall." The Highways Agency procured project, supervised by AmeyMouchel, involved structural repair, as well as widening and re-aligning the highway.

The bridge carried vehicles up to 40 tonnes, but was narrow in width with sharp bends to take it diagonally across the railway.

As part of the Highways Agency's programme to replace all pre-1970s bridge parapets, careful planning was required to ensure minimal interruption to both road and rail traffic.

The new road alignment was carried over the bridge on extensive piling and pre-cast reinforced concrete portal frames.

Tensar reinforced soil wall system was used on both the north and south sides of the railway line as extended wing walls.

The facing units were carried through and across the face of both the new and old abutments.

Tensar Wall System comprises Tensar uniaxial geogrids and high quality precast concrete modular block facing units.

The reinforced fill is generally a well graded granular material, which for Highways Agency schemes would be class 6I.

Maximum height of the structures for this scheme was 8 metres with the wing walls extending 20 metres along the north and 42 metres along the south.

Tensar 80RE and 55RE geogrids are spaced at 450mm vertical centres within the 6I fill material.

The interaction between geogrid and surrounding fill provides the stability for the structure.

The facing units chosen were flint coloured with a textured (split) face finish.

The modular blocks are dry laid and easily manhandled in to position from pallets.

The Tensar geogrids are simply cut from the roll and locked into the face as the blocks are laid, using a unique polymer connector.

The high efficiency of this connection enables a very high proportion of the available safe design strength within the geogrid to be utilised, which would be limited if the connection was frictional only.

The Tensar Wall System has the exacting British Board of Agr?ment (BBA) certification for Roads and Bridges, which is necessary for proprietary reinforced soil retaining wall systems are to be used in public highway schemes.

Wall System units are available in a variety of colours, styles and finishes.

A modular block wall system specially designed to allow a fa?ade of architectural masonry or brickwork to be secured using stainless steel wall-ties is available, where the client demands a particular finish.

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