• Rockley Viaduct

    Good value, high quality materials and service

Rockley Viaduct

Rockley Viaduct

Client - Dyer and Butler
Value - £500,000.00
Duration - 12 weeks
Profile Number - 20/09

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Rockley Viaduct spans between two Victorian rail embankments that bisect parts of Poole Harbour. Its construction thus created a very fast tide race in this part of the harbour, and its problems in terms of long term maintenance become exacerbated by an exceptionally fast flow, a similarly large tidal range, and the very low air draught of the bridge at high water. Another complexity is the inaccessibility of the inner harbour, known locally as Holes Bay.

During the early months of 2020, a Wessex Zone maintenance inspection identified an issue with the revetment protecting the London end abutment of the structure. We were consulted through the minor works framework contractor, Dyer & Butler (D&B), and a bathymetric survey identified that a known scour issue, possibly exacerbated by local dredging for an adjacent marina, now extended to a 13m depth at mean high water.

In collaboration with D&B, we provided the solution in terms of rock infill to the scour void, trimming of failed sheet piles, and repair of the revetment with concrete. This featured our competence in marine operations. We were able to place 2524 tonnes of rock, of up to 3 tonnes in size, utilising periods of slack water, at high tides beneath the structure. This demanded skill and experience, and all passed without incident. Using a previous innovation principle, we created an extension “prod” for an excavator to push rock to a pontoon drop off point beneath the low structure.

A unique selling point of Suttles is the rock and masonry supply that can occasionally be deployed through our sister business, Suttle Stone Quarries (SSQ). SSQ operates several independent limestone quarries, with the same ownership and management team controlling both entities. The market for rock armour in Southern England has largely been supplanted by rock shipped in from Norway, France or Scotland. Whilst there are numerous quarries in the Mendips, the East Midlands and Cornwall, these are mostly operated by nationals with little commercial interest in small orders for specific rock armour at very short notice. With our predominantly rail based contracting work we have a high incentive to demonstrate value in meeting emergency needs like this. This very short notice capability to generate and ship rock to order was again used very effectively at Rockley Viaduct.