CRL accelerates programme and opens lanes 4 months early
During the recent lockdown, CRL was fortunate to be able to start a new project in the Area 10 Highways England region on Helsby Viaduct. This was made possible through CRL’s commitment to work diligently in line with government guidelines, enabling the works to continue safely, and even to accelerate top deck works to allow reopening of all lanes 4 months early.
CRL has undertaken Early Contractor Involvement (ECI) on the project with Highways England and other contractors to develop the access solution, temporary works and bearing replacement and the necessary Environment Agency discharge license. The solution was to design and implement a French drain system with a sump area to divert and control the water run-off from the hydro-demolition works to be processed by a siltbuster.
Safe Road was invited to attend a site survey of the existing parapet system to ensure the new design was within tolerance of the existing and that there was an allowable working area in between the parapet system and the combi safe system installed by Standard Scaffold.
On the top of the bridge deck following initial planning and then milling preparation, repairs to the deck were undertaken before a new waterproof membrane was spray-applied. This was then overlaid with new HRA. The parapet replacements were also accelerated as well, meaning that the bridge could be fully opened to traffic 4 months early.
Significant repairs were also undertaken to the abutment sill. These were carried out in a strict sequence using hydro-demolition for break-out and shutter and flowable concrete to recast the repairs, incorporating Galvanic Anodes in the repairs.
A partition system was installed on the scaffold that segregated the works area into two sections using a visqueen membrane with 2 layers of plywood and a tarpaulin outer face. This system was also used to trap and redirect the hydrodem water run off to the siltbuster.
With the repairs to the abutment sufficiently complete, new corbels, protruding from the abutment, have been constructed. This has allowed the jacking system, including temporary bearings to be placed on these corbels to lift the bridge under a TM closure. The old bearings were then cut out using hydro-demolition and new bearings installed. Continuous monitoring was undertaken whilst the bridge was temporarily supported.
Works carried out include;
- Installation of scaffold / access,
- Initial survey of the sill beam,
- Steel replacement,
- XP4 anode installation,
- Formwork installation & concrete pour,
- Removal & installation of new bearings,
- Planning / milling / deck preparation,
- Repairs to bridge deck,
- Application of waterproofing,
- Removal & replacement of existing gullies, and
- Installation of combi safe system across the works including over a railway line.