Carr Mill Viaduct, St Helens

Client: NETWORK RAIL
Replacement of existing deck with new precast concrete and ballasted p-way on this 120m long viaduct, along with gritblast, painting and steelwork repairs.

Following competitive tender, Story Rail were awarded the contract for the strengthening and refurbishment of Carr Mill Viaduct which comprised the replacement of the existing ‘long timber’ type deck with a ballasted concrete deck complete with continuously welded rail, including steelwork strengthening, grit blasting and painting the superstructure, and replacement of the walkways and parapets.

The six span, 110m long viaduct is supported on five masonry piers was turned into a sealed and encapsulated environment attached to the scaffolding to provide a fully sealed work location ensuring retention of all the debris from the blast cleaning.

Corrosion was significantly in excess of that envisaged and so the steelwork strengthening works were completely redesigned resulting in extensive steelwork strengthening works being required to be undertaken within a short period of time. This involved the installation of both temporary and permanent strengthening works and it is credit to our ability to work under extreme pressure and respond with flexibility and commitment in the lead up to the possession, that these works were undertaken under such tight timescales.

The main deck replacement works were programmed to be carried out within a core possession over the Easter weekend installing the PCC deck units with a Kirow crane. Once the deck units were replaced we replaced the Pway

Following completion of the strengthening works, the viaduct was applied with a specialist painting system known as the “Glass Flake” system. The coatings applied ensure long-term abrasion and corrosion protection under the most severe conditions. The coating system employed for the steelwork requires blast cleaning to bare metal, an application of zinc-based primer to prevent corrosion (35 microns), a glass flake epoxy intermediate coat providing a barrier (400 microns), and a polyurethane gloss top coat to give an attractive finish.

The undertaking of the Carr Mill project presented Story Rail with many interesting challenges. Nevertheless, due to the wealth of experience of the site team coupled with their flexible approach to the ever changing requirements ensured that the works were completed safely and to a high standard.