River Irwell Crossing

Structural Designer

AECOM Mott MacDonald JV

Client Name

Network Rail

Location

Manchester and Salford, United Kingdom

PRINCIPAL CONTRACTOR
Skanska Bam JV

ARCHITECT
BDP

STRUCTURAL ENGINEER (CONCEPT DESIGN STAGE)
WSP

ARCHITECTURAL CONSULTANT
Knight Architects

STEELWORK CONTRACTOR
Severfield UK

PROJECT DESCRIPTION

The Ordsall Chord is a new railway line connecting Manchester’s Victoria and Piccadilly Stations, carried on new and altered elevated viaducts. The Chord’s centrepiece structure is the River Irwell Crossing, the first network arch bridge in the UK, and the first asymmetrical network arch bridge anywhere in the world. Weathering steel is used for the Crossing and all other steel structures, to reduce whole life costs.

Judge's comment:

The challenge of building a new railway bridge among active railway infrastructure cannot be understated, and this project has achieved it with a notable addition to the historic Manchester railway network.

This is the first network arch in the UK, and possibly the first un-symmetric network arch of such a scale in the world, and the judges were impressed not only by the design itself but also by the manner in which the design and construction information was integrated using an innovative BIM approach. The detailed design and construction information was prepared jointly by designer and steel fabricator in a 3D digital space, without the need to generate conventional 2D drawings, leading the way for what is surely the future pattern for design delivery on such projects.

The bridge itself achieves a very slender profile because of the decision to use a network arch in which the diagonal hangers cross at least twice in supporting the deck. There is a very strong architectural element defined by the concept of a continuous "ribbon" which forms the edges of the approach viaducts and the arches themselves, together with a reverse curved feature which dips below the deck in between them, tying the whole ensemble together as a single visual entity. This feature added some complexity but also a unique character to the design, and the judges appreciated that by doing this all in weathering steel the future maintenance burden is reduced by removing the need for repainting over the railway.