A2/M2 Taddington, Harp Farm, Lidsing

Taddington Wood East and West Overbridges (shown to the left) carry an elevated roundabout over the motorway at the redesigned Junction 3.  The overbridges have a total length of 40m, span lengths 20 + 20, and a total steel weight of 2 x 105T.  The six main girders are 910mm deep and braced in pairs.  Longitudinal load effects are resisted by the backfill behind the deck end screens and guided pot bearings carry transverse loads. 

Each main girder was transported to site in two sections of approximately 25m and 15m.  The longer sections were erected during overnight motorway closures.  The shorter lengths were then connected using in-situ bolted splices.

Steel was the selected choice for all of the above bridges, because rapid erection of the main girders kept disruption to motorway traffic at a minimum.  Also the relatively lightweight superstructure allowed the size of spread footings to be minimised.  All of these bridges were built with a standard minimum headroom of 5.3m and all the girders are protected by a conventional paint system giving at least 20 years to major maintenance.