In Hong Kong, the majority of people live in high-rise buildings, many of them right next to one of the rail lines crossing the city, radiating noise that intrudes into adjacent apartments.

Thus, reducing the noise level is one of the most critical and legal design requirements. Trelleborg, in co-operation with other manufacturers, has assisted in one such project in Hong Kong, attenuating noise coming from rail tracks.

Vibration isolation

More than three years ago, Trelleborg Queensland Rubber in Australia started to supply vibration isolation rubber bearings to the Kowloon Canton Railway Corporation (KCRC) West Rail project, linking Kowloon with the western side of the New Territories in Hong Kong.

For the West Rail project, Trelleborg has supplied the floating slab track (FST) bearings, which are designed to support heavy pre-cast concrete slabs on which the rail is attached.

These bearings will reduce the noise generated by the trains to ensure that the new rail system will be one of the quietest in the world.

Vertical bearings

Trelleborg has delivered approximately 200000 bearings to the Hong Kong consortium CHCQ joint venture, which was contracted by KCRC for construction of the permanent way on the West Rail project.

David Kennedy, Business Development Manager, Trelleborg Queensland Rubber, says: "What we developed and supplied was a dual-compound vertical bearing that provides consistent performance over the long term. We'd found that the performance characteristics of the traditional single compound design tended to change over time. Our customer was very appreciative of our development."

Trelleborg Queensland Rubber in Australia manufactured the side bearings, while the vertical and end bearings were supplied from Trelleborg Hercules in Singapore.
Moreover, these components are being delivered for installation on the KCRC Ma On Shan Extension, for which also Trelleborg Wuxi in China are supplying resilient bonded baseplates.

"We're aiming for urban rail authorities with tight environmental and noise constraints that require high-end solutions for rail track isolation," Kennedy says.

Acoustic bearings

Trelleborg Queensland Rubber has also supplied acoustic bearings to isolate noise-sensitive buildings adjacent to rail systems, including the "Theatres on the Bay" in Singapore, and the Hong Kong Movie City project.

"The bearings we've supplied are serving slightly different purposes. The acoustic bearing systems for theatres and studios are designed to eliminate noise and vibration transmitting into the performance areas. The FST bearings installed on the KCRC West Rail are also providing a system of isolation, but they're designed to minimise noise and vibration transmitting out of the rail structure," Kennedy explains.

Alan Crockett, Director of Wilson, Ihrig & Associates - Hong Kong, which is the system-wide Dynamics and Noise Consultant on all of KCRC's new extensions,and the designer of the building base isolation systemfor Hong Kong Movie City, says: "Our specificationsfor trackform isolation and building base isolation systems have developed and evolved over the past30 years.

"The specification requirements result in bearings that have superior low dynamic stiffness, while retaining very long life with little change in mechanical properties over the service period.

"The combination of properties isn't easy for manufacturers to achieve, and only a few worldwide have succeeded. Trelleborg Queensland Rubber and Trelleborg Hercules haven't only succeeded in being able to routinely produce bearings to our specifications, but with the dual-compound trackform bearing and the hi-shear building base isolation bearing, have provided innovations, which are very significant and economically advantageous," Crockett concludes.

For more information, visit www.trelleborgqr.com