Greening Expressways

Green sound barrier

Green noise barrier

If there’s a city that proves the lengths to which a government is willing to go for cars, it’s Hong Kong. Fewer than one in five people here actually own a car; most of the traffic is made up of trucks or some form of public transportation. It’s one of the less congested cities in Asia. Yet the government insists on building new roads at the expense of the city’s environment and quality of life.

The Central Kowloon Route is one of the most recent examples. Current plans call for an expressway to be tunnelled across the Kowloon peninsula, from a highway near the old Kai Tak Airport in the east to the West Kowloon expressway in the west. This in and of itself could be a good thing, since it has the potential to remove cross-town truck and bus traffic from noisy and polluted surface streets. But instead of using the new tunnel as a way to reduce the impact of traffic on surface roads, the government is increasing it. Along with the construction of the tunnel, the Central Kowloon Route will involve the widening of the existing Gascoigne Road flyover that runs through one of the city’s most densely-populated neighbourhoods.

The widening of the flyover is pretty much a done deal, unfortunately, so the question now is how to mitigate its impact. Sound barriers have recently come into vogue here, but they often create visual pollution every bit as nasty as noise, and of course they don’t do anything for the more serious problem of air pollution. To deal with this dilemma, an architectural competition was held for the design of the sound barriers along the rebuilt Gascoigne Road flyover, and the winners, a team of four recent architecture school graduates, found a solution that is both obvious and ingenious: cover the road in greenery. The flyover would be enclosed in a double-layered shell of glass modules that could support vegetation, which would then grow up and over the surface of the shell. The architects pointed to wall trees as their inspiration.

Engineers still need to determine if the winning proposal is technically feasible. If it is, and the government chooses to integrate it into the final design of the widened flyover, it could be a way to deal with the future highways that the government insists on building and the people are mostly powerless to stop.

This entry was written by Christopher DeWolf , posted on Sunday June 07 2009at 07:06 am , filed under Architecture, Art and Design, Asia Pacific, Environment, Public Space, Transportation and tagged , , , , . Bookmark the permalink . Post a comment below or leave a trackback: Trackback URL.

2 Responses to “Greening Expressways”

  • The green expressway reminds me of what I saw in Shanghai a few years ago. Given the city’s goal of making 35 per cent of its surface area “green,” every bush and tree is counted in the green tally. This means that expressway landscaping gets a premium, and in some cases has become linear parks. But from what I saw, most was window dressing, not useful green space.


  • I noticed that in Shanghai — many elevated expressways were lined with planters. But you’re right that it’s just window dressing. What’s really interesting about this idea is that it would probably have a meaningful effect on the surrounding area, both by reducing noise and by reducing air pollution.

    Of course the ideal situation would be to scrap the flyover altogether. HK has a terrible habit of building these things and I don’t think they have much of an impact on traffic. Better-designed surface roads and intersections would probably be more useful to motorists and pedestrians alike. There’s one flyover near my place and I fantasize about what it would be like if it was demolished and replaced with a row of big trees.