A69 Haltwhistle By Pass Railway Viaduct, Northumberland

Client

Morrison on behalf of Road Link DBFO Consortium for Highways Agency

Project Description

The A69 Haltwhistle By Pass was the first DBFO Contract awarded in the UK for a new by-pass to the south of the town. The project included design and construction of a viaduct carrying the highway on a skewed alignment at high level over Melkridge Road, the Newcastle to Carlisle railway, Haltwhistle Burn and an access track. The highway followed a 540m radius curve and the skew angles to each of the obstacles were different and severe and, because the railway was on embankment, headroom at this intersection was critical. As a result there were few convenient locations to construct foundations and long viaduct spans were inevitable. Cass Hayward’s appointment was to conduct a value engineering review of the illustrated design which led to simplification of details, opportunity to speed the site programme and cost savings.

Cass Hayward Role(s)

• Value engineering design review
• Detailed design of viaduct superstructure
• Detailed checking of fabrication drawings
• Detailing of modularised edge precast units
• Temporary works design

Project Statistics

• Completed 10 weeks early in march 1997
• Four span viaduct 214m long with max span 68m
• Main girders 3.2m deep carrying deck 13m above road

Special Features

• Twin girder ladder bridge arrangement conveniently accommodates ground restrictions on foundation locations by requiring fewer single column supports, highway curvature by using truly curved main girders and radial cross girders; and gradual widening of the deck as required for sight lines
• Fast deck slab construction enabled by the use of precast concrete part depth deck edge units and main deck permanent formwork.