Design-development assignment
Newton-le-Willows Railway Underpass
An 18-month design-development assignment for Galliford Try, developing construction methodology for a proposed underpass beneath an operational railway.
The challenge
The brief called for an approximately 30m underpass with around 3m cover to the running rail. Excavation had to be considered alongside the existing platforms, nearby structures and the need to maintain railway operations.
Our role
Our appointment focused on design development and construction methodology. Through Delta Civil Engineering, our team developed the construction methodology and worked with Donaldson Associates / COWI on the specialist temporary works, alongside Galliford Try and Tony Gee. The assignment combined construction-method development, engineering coordination and responses to independent checking.
Design and method
The method was based on interlocking, horizontally installed steel tubes, staged excavation and internal steel frames, with precast concrete underpass units in the original proposal. The design work covered the canopy, internal frames, connections and thrust arrangements, with working-platform and foundation stability considered together. Face-support proposals, excavation stages, frame spacing and unsupported lengths were reviewed for stability as the heading advanced.
Safety and site interfaces
Predicted settlement and deflection during tube installation and excavation were assessed, including movement affecting the track, platforms and neighbouring structures. Ground conditions, buried services, access, plant requirements and the interaction between temporary support and permanent construction were considered. A design risk assessment recorded settlement, heave, excavation-face collapse and buried services.
Assurance record
The project file records Form F002 Statement of Design Intent submissions and revisions, Category 3 checking with drawings submitted to Tony Gee for independent review, and correspondence on the F003 design-and-check process. The evidence relates to the design phase; a final signed certificate is not reproduced or claimed.
