Image: courtesy of Lagan Forrovial
RPS acted as Contractor’s Designer on behalf of Transport Scotland for this major £400m DBFO project comprising a new 12km dual three-lane motorway section of the M8 between Bailliestown and Newhouse, with three new grade separated motorway junctions and amendments to two existing motorway junctions. It also comprised upgrades to approximately 16km of the existing motorway network including widening for additional lanes, realignments, drainage, mining stabilisation works, environmental mitigation and provision of Intelligent Transport System (ITS) across the network.
RPS carried out the detailed design for 40 structures on the project; of which 23 were new structures and 13 existing bridges were widened and/or strengthened. The project also involved traffic signals, lighting, drainage, pavement, road markings, footways and cycleways, road markings, soft ground challenges (including deep peat), environmental management, gantries, noise barriers and demolition of existing structures.
Raith Interchange was the most complex element of the scheme involving the construction of a new underpass structure to provide free flow for the existing A725, the realigned Raith Roundabout, three new bridge decks, pedestrian and cyclist facilities over the roundabout and flood alleviation storage ponds. RPS delivered a combined temporary and permanent works solution for the junction. The detailed design for the underpass at Raith, approximately 600m long, included a secant pile wall solution with inclined ground anchors at the head. The anchored solution optimised secant pile diameters and toe depths and controlled lateral wall deflections while increasing durability performance.
RPS developed a BIM model of the interchange, a collaborative effort between RPS, contractor and O&M teams. The use of BIM enabled our permanent and temporary works designers to coordinate the design of the permanent works with traffic management, dewatering and temporary works.
This project was awarded an ACEI Design Excellence Award in 2018.