THE SCHEME
Congleton Link Road is a 5.5km carriageway joining the A534 Sandbach Road (to the west of Congleton) with the A536 Macclesfield Road (to the north of the town). The project will significantly reduce town centre traffic congestion, cut pollution and improve air quality. Bachy Soletanche was awarded a contract by GRAHAM, to deliver the geotechnical works at five different locations on this Cheshire East Council infrastructure scheme.
CONSTRUCTION
The complex scheme required foundations and piling work across multiple sites which provided planning and logistical challenges. The works consisted of:
Giantswood Lane Overbridge:
The team installed 34, large diameter rotary bored (LDA) piles for the bridge abutments. These piles were 880mm in diameter and were bored to a depth of 25m. The LDA method was selected due to the required length of the abutment piles, these piles were constructed using segmental casing. In addition to this, 66 CFA piles with a 900mm diameter were bored up to 17m to form a contiguous piled wall. Ground conditions proved challenging on this location but through close collaboration with the client and operations team, these were overcome.
River Dane Bridge (East):
The Eastern section of this bridge required 22 large diameter rotary bored piles of 1200mm diameter to be bored 25m to provide support for the bridge abutments. Unexpected ground conditions required a change in the casing, moving from four metre slip casing to nine metres. This approach meant the weak mudstone could be navigated and a stable bore could be continued past this point.
River Dane Bridge (West):
The Western side of the bridge only require eight large diameter rotary bored piles. These were 1200mm in diameter and were bored to 22m. The site was logistically challenging with there only being enough room for either the rig or the crane. Plant movement and site management became essential to the success of this operation, with the team managing to achieve an output of one completed pile per day.
Loach Brook Bridge:
This structure required piling for the abutments on both the Southern and Northern sides of the brook. Due to their only being one bridge between the abutments, it was not possible to work on both locations at once. The team initially installed 12 piles on the South abutment, these were 750mm in diameter, bored to 27m and constructed using the large diameter rotary bored method. Once completed, the rig moved to the North abutment site and installed a further 12 piles of the same size, using the same method. During this time, the crane, tremie racks and ancillary items remained on the Southern side, ensure limited movements.
Chelford Road Overbridge:
This site required a substantial amount of piling with the requirement of two secant walls, one on the north approach and another on the south approach. Approximately 250 cased secant piles (CSP) were constructed to form the walls, the 900mm diameter piles were bored to depths of up to 19m. The mudstone clay provided team with challenging conditions in which to drill the piles, but one they successfully overcame.
The Congleton link road project was a good example of how collaboration between stakeholders can help drive efficiencies and ensure any challenges can be overcome. The £90m scheme opened to traffic in mid-April 2021.
