Bethell Construction

Phillips Road Culvert, Blackburn

Philips Road Culvert carries the River Blakewater and runs perpendicular and parallel beneath Philips Road in the Little Harwood area of Blackburn. The existing structure comprises masonry side walls and a 6.0m span concrete roof deck.

85 metres of the existing reinforced concrete roof deck had been assessed as substandard and required replacement with a 600mm deep reinforced concrete roof plus new abutmnet bearing shelves.  In addition, the existing abutments were widened and strengthened by introducing mass concrete to the outer faces, this operation being undertaken in advance of the new structure and executed in a ‘hit and miss’ procedure. 

The closure of Philips Road was not possible therefore prior to works commencing, a temporary road widening was constructed to allow single file traffice to be maintained during the works.

A temporary support system had to be designed to support the 600mm deep slab and the Environment Agency stipulated that the existing cross sectional area of the culvert could not be compromised. The innovative solution involved designing a structural steel frame whch was supported off the neew bearing shelves.

In addition to the substantial in-situ concrete works involved in the slab replacement, a 7.0m length of upstream retaining wall was replaced plus the upstream bridge parapet. Both of these members were clad in natural stone.

Once waterproofing works were completed, substantial reinstatement works involving new carriageway, footways and landscaped areas were completed in-house by Bethell.