SSDA 2018 A W A R D
22 NSC
October 18
The Ordsall Chord
Viaduct
The Ordsall Chord Viaduct is the
iconic centrepiece of the new
elevated railway that connects
Manchester’s three main railway
stations for the first time.
It carries a new two-track railway
across both the River Irwell and Trinity
Way dual carriageway. It sits next to major
heritage structures, part of the historic 1830
Liverpool to Manchester Railway, the world’s
first inter-city railway.
The context required a design which was
of the highest architectural quality, with a
structure which would act as a landmark
without dominating surrounding buildings.
Television presenter and former MP
Michael Portillo says: “Based on what I’ve
seen, the Ordsall Chord will be destined to
become a Manchester landmark.”
An 89m span network arch structure was
chosen for the main river span, combining
great strength and stiffness with a relatively
low profile. A 100m long twin girder bridge
was selected for the spans over the roadway.
All parts of the viaduct are integrated
visually to appear like a single ribbon of
weathering steel, tapering at both ends,
and sized to suit the specific structural
requirements on the individual spans.
“From the early stages of design,
weathering steel was considered to be the
ideal surface finish for the structures. It
provides an honest expression of the material
in terms of its function, colour and texture,
echoing the historic masonry that sits
alongside,” explains BDP Architect Director
Peter Jenkins.
The preliminary design concept
illustrated box girder structures throughout
the length of the viaduct. The design was
modified during the design-and-build phase,
adopting box girders for the arch ribs but
stiffened plate I-girders for the spans over the
highway. This reduced construction cost and
simplified future maintenance requirements.
The network arch is visually merged
with the girder spans above Trinity Way by
the inclusion of steel ‘cascades’ in between.
These transition pieces negotiate complex
changes in vertical and lateral geometry,
and give the impression of a smooth
transformation from the hexagonal box to
the ribbed I-section.
The river and highway spans of the
viaduct both employ steel primary girders,
with steel cross-girders supporting a
composite concrete deck slab. The main
span’s hanger network comprises solid steel
hangers each 85mm in diameter.
Steel was the most cost-effective
solution to satisfy the client’s structural
performance requirements and also the
desire for an elegant, iconic structure. Steel
was ideal for the offsite manufacture of a
highly geometrically complex structure,
and allowed an efficient construction
methodology to be developed.
The network arch was the biggest
structural challenge. An existing road bridge
The Ordsall Chord Viaduct includes
the first network arch bridge to
be built in the UK, and the first
asymmetric (tapering) network arch
anywhere in the world.
© Matthew Nichol Photography
/Design
/Bridges#Arch_bridges
/Ladder_deck_composite_bridges
/Bridges_-_initial_design
/Box_girder_bridges
/Ladder_deck_composite_bridges#Main_girders
/Ladder_deck_composite_bridges#Main_girders
/Ladder_deck_composite_bridges#Cross_girders
/Tied-arch_bridges#Hangers
/The_case_for_steel#Offsite_fabrication_for_precision_parts
/Design_for_steel_bridge_construction