e-mosty December 2017 MSS and Formwork Travellers | Page 54

Temporary trestles were installed in the river with a
dual purpose – to support an existing highway bridge
while it was demolished in pieces, and then to support
the new bridge deck during construction. The new
arch tie girders were erected in three pieces each,
then cross-girders were installed.
The two arches were welded in sections at ground
level, rotated to their correct angle, then connected
with cross-bracing and temporary ties and struts.
The double-arch assembly was erected using a
tandem crane lift, one 750-tonnne and one 1300-
tonne crawler crane, the latter being the largest
available in the UK.
The Ordsall Chord Viaduct
The River Irwell Crossing is just one of several
structures which make up the Ordsall Chord Viaduct.
To the north of the network arch bridge, the viaduct
spans Trinity Way, with a 110m long three-span half-
through girder bridge comprising 3.0m tall edge
girders and a composite ladder-deck.
Two single-span half-through girder bridges were also
built across Water Street, both installed using self-
propelled modular transporters.
Between the River Irwell Crossing and Trinity Way
Bridge, a “king-pier” structure provides resistance to
longitudinal railway loads. This structure also supports
two giant steel “cascades”, the most complex steel
pieces on the project, which provide architectural
continuity between the structures on either side.
At both ends of the viaduct, existing 19 th century brick
railway viaducts have been widened using reinforced
concrete arch spans.
The concrete arches were precast off site and are
supported on cast-in-place concrete piers, and infilled
with mass concrete. Due to irregularities in the
construction of the existing viaducts, and their
curvature in plan, every concrete arch and pier are of
a slightly different dimension.
The project also included extensive refurbishment of
the historic structures, including the complete
reconstruction of one elevation of the two span
masonry Stephenson’s Bridge.
This bridge holds the highest heritage protection
status in the UK, and formed part of the historic 1830
Liverpool to Manchester Railway. After years of
damage and neglect, the north elevation has been
rebuilt to match its original 1830 appearance.
The project also required construction of a new
pedestrian and cycle bridge, Prince’s Footbridge,
immediately below the River Irwell Crossing.
This is a 50m span steel spine beam structure, with
aluminium decking and stainless steel parapets. It is
believed to be the first bridge in the UK to be
designed and built directly using only the digital
design model, without conventional design detail
drawings.
Figure 2: Stephenson’s Bridge reconstruction
© Matthew Nichol Photography
4/2017
Figure 3: Installation of Water Street Bridge
© Matthew Nichol Photography