Bidston Moss Viaduct Strengthening

Client: Costain

Location: Bidston Moss, Merseyside

Project: Strengthening and refurbishment of the Bidston Moss viaduct

Service: Access



The Bidston Moss viaduct is jointly owned by the Highways Agency, Wirral Council and Merseyside Passenger Transport Authority (MPTA).
The Challenge
Working for principal contractor Costain, Denholm Industrial Services was a full alliance partner alongside designers Amey and strengthening contractor Cleveland Bridge UK.  The Denholm Industrial Services (DIS) scope included:
  • Scaffold and full encapsulation
  • Surface preparation
  • Application of protective coatings
  • Emergency response and rescue teams for all trades

The Solution

This project was complicated by the high volume of works required to be undertaken within the extremely confined box girders, which were no more than 1.2m high throughout the full span. This was further complicated with the need for ‘non-compatible’ trades to work in close proximity with each other: welding, burning and hot-works were carried out simultaneously with the application of solvent based paints. Furthermore, the viaduct crossed over public highways, railway lines and was located adjacent to a Site of Special Scientific Interest (SSSI).


Works completed by Denholm Industrial Services included the surface preparation of over 136,000m2 of steelwork and the subsequent re-preservation thereafter. We also delivered, erected, maintained and dismantled over 2,600 tonnes of scaffold materials to provide a fully designed access solution to the 4km of box girders. This scaffold was subsequently fully encapsulated with a double skin containment.

Even with the inherent risk and uncertainty attributed to this type of maintenance, the project was a great success.  Highlights include:

 1,290,000 man-hours worked over 37 Months
 No reportable accidents, AFR = 0.00
 3 RoSPA Gold awards
 Scheme delivered under budget
All key milestones achieved
 Early contract completion including handover
 Removal of BD79 three months ahead of programme
 First Highways Construction Project to be accredited to BS11000 for collaborative working and relationship management
 Received ten highly acclaimed industry awards and short listed for many more