The White Cart Viaduct is an elevated section of the M8, which carries the motorway over the White Cart Water close to Glasgow Airport. The bridge comprises a concrete deck supported on steel box beams with a 73m main span. Transport Scotland recently implemented a scheme to improve access under the bridge deck to aid inspection of the underside, particularly the inside of the box beams to check for corrosion. This involved the design and construction of a new 2m wide walkway, spiral stairs and cross platforms under the deck. The walkway units were constructed from Fibre Reinforced Plastic (FRP) as opposed to the more conventional steel option. Despite material costs being increased, FRP units are lightweight and durable, resulting in little or no maintenance over the 60 year lifespan required. The light weight of the FRP imposes less load on the main bridge and is much easier to construct at height, where restricted access under the bridge prevents cranes from operating . The walkway was made up of 3m long modules each with grated floor and sidewalls lifted into position using roped access techniques and clamped to existing cross girders. MHB carried out outline design of the overall scheme, and independent checking of the walkway units (which were designed and supplied by Pipex). The construction of the scheme was competed by AMCO in December 2016. Roped access sub-contractor was Geo-Structural. Photographs of the walkway under construction follow.
MHB Consultants recently carried out condition surveys and design for an upgrade to the pedestrian footbridge at Monifieth Station. The three-span, metallic, lattice girder footbridge crosses the Edinburgh Waverly to Aberdeen line to the west of the station. The structure is Grade B listed and is located within a conservation area and special protection area. The existing bridge required condition-led repairs including extensive works to the main girders and lattice parapets. In addition the timber bridge deck was in poor condition and required complete replacement. Consideration was given to installing a similar timber deck, however a novel feature of the design was that it was decided to adopt a Fibre Reinforced Plastic deck to reduce maintenance and whole-life costs.
Following repairs and deck installation the bridge was fully repainted to comply with the historic requirements of the conservation area. FRP Deck Panels were supplied by Relinea and the works were completed by main contractor AMCO in January 2017.
Some before and after photographs are provide below.
MHB Consultants are looking to recruit two graduate engineers, one to work in our bridges department and one in our civil/ geotechnical department. The closing date for applications is 28th February 2017.
For more information see our 'Jobs' page.