Testing of the design was carried on a 1/12th model at the Research Station of the Cement and Concrete Association at Wexham Springs in South Bucks. The design was made by the consulting engineers G Maunsell & Partners, who had designed the similar Hammersmith flyover in 1961. The company was known for prestressed concrete flyovers. The design received a Concrete Society award. The designer of the bridges would go on to design the Westway dual carriageway in London, which opened as the A40(M) in July 1970, losing its motorway status in 2000. Construction The construction was carried out in two phases: the first stage involved the construction of a dual carriageway of 2,850 ft (869 m) to the east of the A6 road in November 1963 and was opened to traffic as part of the A635 road in November 1965. The second stage was the construction, from December 1964, of a 0.6 mi (1 km) long elevated highway of a motorway standard which ran between the A6 and A56 roads. The second stage was open to traffic as part of the A57 road in March 1967. The previous day it was opened to pedestrians, who were allowed to walk the whole of the high-level route as a sight-seeing publicity exercise. Many people brought picnics which they ate in the centre of the carriageway. At that time, the construction specifications had included cosmetic fairings to the tops of the support piers. These completely enclosed the roller bearings upon which the elevated roadway sits. However, the first time these bearings were serviced, the fairings were removed and never replaced. This leaves the poorer appearance seen today and also allows the ingress of dirt to the bearings. Leonard Fairclough & Son were the contractors, and the prestressed concrete sections were made at its operations in Adlington, Lancashire. The contractor's site compound was in Loxford Street. The piling was completed by Pigott Foundations of Ormskirk with auger (screw) boring with reinforcement cages. The piling went 50 ft (15 m) deep through the boulder clay to the Bunter sandstone (Buntsandstein). The road on the structure and kerbing was built by Wilson and Wilkinson of Worsley in Salford. Opening The Mancunian Way was officially opened by Prime Minister, Harold Wilson, on 5 May 1967. In the 1970s, it was upgraded to motorway status as the A57(M) and the speed limit was raised to . At the