Civil Engineering Reference
In-Depth Information
11.6 Case history: River Nene Bridge
The 139.2 m long River Nene Bridge carries the dual carriageway Nene Valley Way
over the River Nene and a single-track railway, close to Northampton. This bridge was
designed by the author when at Arup, with the participation of Arup Associates. The
highway alignment was fi xed, as were the clearances required over the railway and the
access road on one bank of the river, leaving available only a 700 mm structural depth.
Adopting a continuous solid prestressed slab would have required fi ve internal spans
of 20.5 m (span/depth of 29.4), and two end spans of 18.4 m. This number of spans
was not suitable, functionally or aesthetically.
A four-span solution was adopted (29.7 m, 39.9 m, 39.9 m, 29.7 m), using a 700 mm
voided slab which was haunched over the three internal supports, Figure 11.16. The
bending moment was attracted from the spans to these haunches by building them
into their piers. In order to allow the bridge to change in length under temperature
variations and concrete shrinkage and creep, each pier was split into fi ve thin precast
concrete planks. The planks of the central support, which were not subject to length
changes, were shorter and hence stiffer than those of the intermediate piers so they
would attract a larger proportion of the longitudinal external loads applied to the
deck. The voids were made of polystyrene, Figure 11.17.
Figure 11.16
River Nene Bridge (Photo: Arup)
