Skybridge Ribs

An elevated guideway and pedestrian deck for a short automated transit line in a Kansai suburb, running two kilometres between a station and a hospital campus.

Infrastructure of this kind is normally engineered and then apologised for. Kawase Structures was appointed at concept stage with a brief that treated the guideway’s appearance as part of its function, on the argument that a structure two kilometres long and six metres above a residential street is the most-seen piece of architecture any of those residents will encounter.

The beam is post-tensioned precast concrete, cast white with a titanium-dioxide additive that resists the soot staining that darkens most elevated structures within a decade. Its web is pierced by a repeating series of long oval voids, which reduce dead load by about eleven per cent and, more importantly, let light through the beam. From below, the underside is deeply ribbed, and the ribs are spaced so that a person walking beneath sees a slow strobe of light and shadow rather than a continuous ceiling.

Piers are single cylinders, tapering slightly, with no capital. The beam sits directly on a concealed bearing so that the junction reads as a plain meeting of two shapes. The practice removed the flared pier head that the original engineering scheme proposed, absorbed the resulting moment in the beam, and accepted the cost.

Where the guideway meets the pedestrian deck, the same oval voids continue through the parapet, and a planted strip runs along the top of the deck edge. One of those planters is visible in the photograph, holding a young tree.

The jury respected the argument and the finish quality, particularly the pier junction. It placed the project in Honorable Mention because the entry documented only a short section of a much longer structure, and because the stations, which are where the line meets its users, were designed by others and are not to the same standard.