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SoundSorb specified for use in Hong Kong West Rail Project

February 2002

Hong Kong – The durable, acoustic cement-based material SoundSorb has been selected for use in the West Rail project, a high-speed railway that will help serve Chinese commuters in reducing traffic overload in that country.

Roundel, CSI’s licensee in Hong Kong, is producing SoundSorb retrofit panels for application to previously installed parapets and wet casting the cement-based SoundSorb material on the new rail parapets prior to installation in an effort to reduce noise once West Rail, a high-speed commuter train that has been called “the missing link in mass transit service” in Hong Kong.

The West Rail Phase I railway construction program, Hong Kong's largest infrastructure project, is 30.5 km long and will provide rail service between areas of growing population in the northwest New Territories and urban Kowloon. (Kowloon, 9 square km or 3½ square miles, is a peninsula on the southern edge of the New Territories.) The Kowloon-Canton Railway Corporation (KCRC) is a public corporation charged with the task of operating and developing domestic, cross-boundary and inter-city railway services in a prudent commercial manner, and therefore the KCRC is overseeing the entire West Rail project.

When the railway becomes operational at the end of 2003, West Rail will serve 340,000 passengers a day; demand is expected to grow to 500,000 passengers a day by year 2011.

Initially, 20 trains of seven cars each per hour per direction will be put into service. Ultimately West Rail will be capable of handling 33 trains of nine cars each per hour per direction. West Rail, an electrified railway, will not only reduce a significant amount of road traffic exhaust emission but is also expected to decrease air pollution in the area by 1,000 tons annually.

According to the KCRC, before construction began, a comprehensive Environmental Impact Assessment (EIA) was completed “to identify potential environmental impact arising from the construction and operation of West Rail and to develop appropriate measures mitigate those impacts. KCRC has addressed these environmental concerns, including potential noise from the railway itself to the surrounding communities, from the preliminary design stage to the detailed design of West Rail.
”A revolutionary, multi-plenum, noise-attenuation system, together with other noise mitigation design measures, will make West Rail one of the quietest railways in the world,” according to the KCRC’s website. “The system is comprised of three main components: a plenum beneath the train involving the use of vehicle skirts and under-car sound absorption; a plenum located beneath each walkway, on both sides of the track; and edge barrier walls with sound absorption. These measures will significantly reduce the need for high-level noise barriers that would be visually obtrusive. This is the first time a railway will be built with all of these measures integrated in a system as a total solution.”

Such lower-level noise barriers are made possible in part through the use of CSI’s SoundSorb material that is lining and edging the barrier walls of West Rail. This cement-based, flowable material has a Noise Reduction Coefficient (NRC) of 1.0 at 3.5 inches and high readings at specific frequencies important to the project. The specifications for the West Rail project were much more stringent acoustically than most sound wall project bids request. When another product could not meet these demands, SoundSorb was approved for the project because it exceed the specifications and was also much less expensive.

The West Rail project is unique because it marks the first time SoundSorb has been poured vertically. In addition, the parapets are curved, which could have posed a problem for other sound abatement materials. Because SoundSorb is a very moldable material it could be wet-cast inside the interior framework of the concrete parapets. A fractured fin texture was then “stamped” onto the SoundSorb material to achieve greater sound absorption and to discourage graffiti on the material. (Acoustical textured material can be applied to both sides of a barrier if desired. Custom artwork can also be created using SoundSorb.)

Retrofitting installed structural concrete parapets is more time consuming and labor intensive than pouring the concrete structure and adding the SoundSorb acoustical material immediately, allowing them to cure integrated. The retrofit SoundSorb panels must be poured in multiple-sized forms, stamped, cured and then hauled to the site, raised onto the West Rail platform and then added to installed parapets with special adhesive. It’s much easier to pour the materials at the same time and thus avoid retrofitting, but because SoundSorb was approved for use after the project was underway many of the parapets were already installed, which made retrofitting was unavoidable.


While SoundSorb’s biggest advantage over the competition is its noise absorption properties, one of its best features is its durability in a variety of weather conditions. Wet weather conditions can actually help strengthen the cellular structure of the material over time. SoundSorb also resists rotting, mold and mildew build-up, rusting, warping, insects and bird and rodent nesting.

Residents near sound walls built with SoundSorb in Beijing, China; Melbourne, Australia; Yokohama, Japan; and several large cities in the USA have discovered the benefits of noise reduction near busy highways and railways. (Visit our website at for more information.)

Regarding West Rail, the people of Hong Kong will benefit from a new mode of transportation that is faster, less stressful, more efficient and that reduces engine emissions without paying the price of growing noise levels in one of the world’s most populated cities. Concrete Solutions, Inc. is proud to be involved in the West Rail project, providing a solution to the negative effects of noise on the environment and the people who live and work in Hong Kong.

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