M2 Junction 5

The M2 junction 5/A249 Stockbury Roundabout in Kent was one of the top 50 national casualty locations on England’s major ‘A’ roads and motorways and could not cope with existing traffic flows. Junction improvements were proposed in Kent County Council’s 2010 framework for regeneration and in the South East Local Economic Partnership’s Growth Deal and Economic Plan 2014 to support economic growth accompanying future housing and employment growth in the area.

The road network was redesigned to provide a grade separated junction spanning a new roundabout and a series of six extensive retaining walls of up to 8m in height and cumulative length of 980m. The challenge was not only the scale of the intervention but also its sensitive location within the Kent Downs Area of Outstanding Natural Beauty (AONB).

Knight Architects’ solution pays homage to the history of local construction where flint, historically a waste material from farmland, was used for wall infill in the construction of buildings and field boundary walls. The perception of the walls by users whether looking from up close or from afar, and travelling at low and fast speed, was an important consideration in the design process.

Knight Architects prepared a set of guidelines that helped the manufacture of each handset panel so the c. 3000m2 of retaining walls integrate well into the landscape. The design uses flint as the finish material on precast retaining wall panels to enhance its aesthetics, with intermediate ribbed panels to break the scale of walls. The bespoke design secured the support of the planning authority and delivered a reduction in the quantity of stone by more than 30% from the scheme approved at DCO.