Ashley Scott Kelly

Structure

Tsuen Wan Bypass Barrier

Collaboration: Ashley Scott Kelly; Mathew Pryor; Christopher Zhang

Abstract

The project recognizes not only the high visibility of the barrier but also the impact of doubling the viaduct through Tsuen Wan and its potential for making legible environmental, structural and sustainable performance in the civic spaces of Hong Kong. Two simple geometric forms, a field of aluminum tubes and a steel diaphragm canopy, are combined to absorb traffic noise while conveying the design's performative aspects.

Acoustic Dampening Field & Visualizing Structural Separation

The system is able to maintain its design language within the varied constraints and narrow limits imposed by adjacent buildings. The transition from wall to canopy becomes key and is resolved by separating (aesthetically and structurally) the lightweight tube construction from the steel canopy frame, conceptually emphasizing the separation necessary to prevent corrosion. The barrier's wall is composed of a "field" of aluminium tubes. Narrow slots patterned on each tube absorbs part of the traffic noise, while it's circular shape reflects the remaining sound throughout the field to achieve maximum dampening effect. The crisscrossing canopy frames act as a baffle to provide further sound dampening. The canopy's structural diaphragm is supported on cylindrical steel columns staggered among the aluminium tubes for increased structural stability. The diaphragm's spacing varies to account for both changes in road width and loading distribution, which is aesthetically registered on the inner and outer barrier faces. The aluminum tubes are fitted into an array of eighteen different modules able to accommodate all sizing conditions along the length of the freeway, while achieving a seemingly smooth transition along the canopy lattice. These modules are also easily maintainable and replaceable. The structural separation of the aluminum and steel components is emphasized on the roof through bimetallic transition joints located on the frame's grid, and in elevation through perforated surface treatment and anodizing.

Pedestrian Scale & Occupiable Structure

The size and patterning of the aluminium tube, coupled with cylindrical steel supports, gives the design a level of articulation that is both beautifully ornamental and acoustically and structurally performative, breaking down the monumental span of the highway to a pedestrian scale. The design further enhances this interface by incorporating a walkway between Tsuen Wan West Station and the architecturally significant Clague Garden Estate, inhabiting the structure necessary to support loads on the central noise barrier. This is the only at-grade location where a pedestrian will come in direct contact with a part of the barrier. The design uses the same structural diaphragm logic from the Bypass's full- and semi-enclosures, varying frame spacing in response to varied height and load. Because of immense shading from the Bypass (an increase of the viaduct's overall width at this location from 37 to 60 meters), piezo-electric generators are incorporated into the new roadbed to power lighting for the passage and surrounding neighborhood. Further, a new planting strategy of shade-tolerant vegetation adds to making the structural, sustainable and environmental performance clearly legible and demonstrative to the heavily-used Tsuen Wan Park and waterfront.

View from Tsuen Wan Park with completed Bypass.
View from Tsuen Wan Park with completed Bypass.
Auto view from within semi-enclosure.
Auto view from within semi-enclosure.
View from Clague Garden Estate.
View from Clague Garden Estate.
Design principles.
Design principles.
Acoustic dampening field.
Acoustic dampening field.
Panel module types.
Panel module types.
Shade-tolerant planting strategy.
Shade-tolerant planting strategy.
View of Bypass along new TW6 development.
View of Bypass along new TW6 development.
View northbound.
View northbound.
View from recreation area of Clague Garden Estate.
View from recreation area of Clague Garden Estate.