Strood & Higham Tunnel
Client Costain for Network Rail
Skills Tender Planning & Presentation, Interim Programme Management, Pre-Construction Design Development
Value Est. £25m
The project involved relining sections of the Strood and Higham rail tunnels in Kent, some of which were unlined others had been previously lined in the past. The work was to be carried out for Network Rail (formerly Railtrack) within a critical and predetermined rail ‘blockade’ period.
The tunnels were former canal tunnels constructed in the 19th Century through Chalk and subsequently converted for rail use. A number of falls of chalk in the unlined sections had resulted in previous mitigation works and the installation of advance warning systems. This project was designed to finally resolve the ongoing safety issues and provide a secure asset.
The design of the new lining had been the subject of a detailed assessment with one of the main criteria being minimum disturbance to the insitu ground. The selected system was based on the installation of both steel arches and an in situ concrete lining.
Subsequent design development during the tender period and post contract award optimised the arch sizing and spacing, foundation details, temporary support and excavation methods, lining alignment, thickness and placement techniques.
During the tender period, LBA provided technical support to Costain for the design and pricing of the works. Following the successful award of contract, LBA provided further technical and planning support to Costain during the subsequent construction phase.
- Input during the early stages proved critical to the success of the design, construction methodology and programme which won the contract.
- LBA were actively involved in the detail design and planning of the works in conjunction with Costain and Halcrow who were the contractor’s designers.
- LBA took the lead in the design of the secondary lining methodology. The use of a full profile crown shutter specially designed for this particular application along with the use of a self-leveling concrete proved crucial in achieving the required structural requirements, with minimum disturbance to the ground, while maintaining the progress outputs needed to meet the tight programme.