Alder Root Culvert
Overview
Culvert repair to failing structure that carries 4 electrified lines on the West Coast Main Railway Line north of Warrington.
The total length of the culvert was 41m with a bend at approximately 15m from the upside end. There was an access chamber situated at ballast level in the 10 foot that led to the invert of the culvert. The superstructure consisted of 3 no. red/blue brick arch rings. The upside headwall was constructed of brick, with the downside headwall of concrete construction with an area of corrugated steel sheeting supporting this headwall.
The Works
The scope of the work comprised:
- The removal of all vegetation within 3m of the bridge, 2 weeks before work on site
- Excavation of inlet and outlet areas of culvert and temporary removal of catch pit at outlet to create safe access and egress
- De-silt and de-water culvert by creating a sump assisted by a jet vac unit and pumps with silt/spoil removed to licenced tip
- An inspection report was undertaken and potential repairs were highlighted on a priority scale to enable the client to establish final scope based on available budget. A laser sweep of the culvert determined the profile to confirm dimensions of GRP sections
- Brickwork repairs were made to defects within the culvert
- Bespoke GRP liner was installed by tele handler from both ends of culvert and mechanically pulled in from the mid-sections
- Repair of the head walls and wing walls
Key Challenges
- The inlet & outlet was located within a farm/livery stable and consideration had be to given to pedestrians, horses, farm traffic etc
- Working within a watercourse with water levels continually monitored
- Ecological restraints were in place with no work being undertaken during the great crested newt’s hibernation season and if newts were seen this was reported to an ecologist for removal
- Working near electrified lines on the West Coast Mainline
Works within the culvert were treated as confined work space.
Added Value
A change to the design was required after we conducted a laser survey that revealed the GRP sections specified, in our view, were unsuitable for the project with the team providing an improved safer solution. The proposed UV lining that was preferred over GRP sections gave us an additional week off the programme.
We look to recycle value in local economies so we use local labour and subcontractors and on this project they all came from within 25 miles of the site.