Brindle Chapel Underbridge Reconstruction

Project Outline

Murphy replaced the existing single span underbridge located in Brindle Chapel, Preston during a 52 hour possession. The structure carries the up and down lines from Preston to Blackpool over a single carriage public road. The existing superstructure was replaced using two U-type steel billet decks on new reinforced concrete cill beams. This replacement required a track removal over the bridge span which allowed conventional ballasted tracks to be installed upon completion of the replacement works.

Key Challenges

Due to restricted room for craneage, we made the decision to install the bridge using a self propelled mobile transporter (SPMT). On previous similar projects, the new bridge would be assembled on site on jacks at approximately 5m height two weeks prior to the installation. Operatives would then work on the new bridge whilst working at height off cherry pickers. The same process would be used for removing the existing bridge. On this occasion we used a gantry system, allowing the bridge installation and all works to be carried out at ground level. On the core weekend the gantry then raised the new bridge to the required height so that the SPMT could drive the new bridge into position.

Project Delivery and Innovations

To minimise disruption to local residents and the general public the bridge was built off-line, bridge elements were delivered to the compound area where they were erected and assembled on the hydraulic gantry system using 200t mobile crane prior to the core possession. Using the gantry system also removed the risk of working at height, reduced programme and saved on project costs. Trial erection of the bridge was undertaken at the manufacturing facility prior to the delivery to site to ensure dimensional and build accuracy.

A 400t capacity SPMT was used within the core possession to remove the redundant existing bridge and install the preassembled new bridge structure, this reduced preparation timescales, road closures and service disruption.

The Murphy design team detailed a simple and effective ballast retention system using steel H beams and concrete planks which could be largely installed in advance of the core possession and as part of the bridge assembly in the compound. This reduced risk during the possession as it required less installation time and delivered an overall cost saving for the project. This detail is being promoted as best practise for future schemes. 


Network Rail


Preston, Lancashire

Completion Date

December 2017



Despite everything mother nature threw at us over the weekend we successfully completed another scheme. Many thanks to everyone involved in the excellent planning & implementation of the project. - Ian Jones Network Rail

Capabilities Demonstrated

  • Rail
  • Engineering
  • Bridges

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