The Roads and Traffic Authority (NSW) project involved the design, supply and install an approved 170m long Reinforced Soil Wall (RSW) as part of the Central Coast Highway Upgrade.
The wall design required careful con-sideration of existing land contours, ground conditions and traffic loads as some sections of the wall footing would be in uncontrolled fill zones.
To provide a suitable base for the wall which had high bearing pressures to exert on the foundation these uncon-trolled fills were removed and re-placed with cement stabilised materi-als.
In addition, the RSW design needed to incorporate a large existing seg-mental block retaining wall located behind the backfill zone of the new wall.
The challenge was to ensure that drainage from the existing block wall outlets was captured and integrated into the new RSW drainage design to discharge groundwater from the back-
fill zone, thereby relieving any pore water pressure exerted on the wall face