The angling of the panels, in turn, creates a wonderful sense of lightness and space, particularly where the path passes under the new Bowen Place vehicle bridge.
“When you think of a traditional underpass you think of tall, vertical retaining walls that create a typically dark, dank space,” says Andrew Nimmo, of lahznimmo architects.
“Our approach was to try and open the space up as much as possible. So at the point where the path passes under Bowen Place, we’ve widened it out to six metres and leaned the precast panels at an angle of 45 degrees.
“As they move away from the underpass towards the Kings Avenue Bridge, the angle of each panel increases by half a degree until they eventually get to vertical. “What this creates is a sense of opening and closing of the space. It also creates a dynamic feel because of the gradual shift in the angle of the panels.”
The top of the panels rise above ground level to form a natural balustrade, adjoining an insitu concrete ‘lip’ that acts as a mowing strip. The gap between the panels also opens out from about 30mm at the base to a maximum of 115 mm at the top, creating a beautiful shading effect.
Because the panels vary in height to adjust for the rising gradient, precasting came into its own.
“To take full advantage of the efficiency of precasting, you use a mould and repeat the process. In this case, we simply used a shutter at one end of the mould to adjust the lengths of each panel,” Andrew says.
The precast concrete mix included a white cement, together with quartz and a spectrum of dark coloured stones that are exposed through the polishing process. A sacrificial anti-graffiti coating was applied to the exposed side of each panel.
The path itself is insitu concrete with an acid-etched finish that creates a textural contrast to the walls.