VSL Hong Kong Railway Expansion Joints

Boss Polymer Technologies and Granor Rubber entered into a joint venture agreement to supply VSL Hong Kong with two specialty, custom designed expansion joints for use in the Taiwan High Speed Rail Project (THSR). This joint venture capitalised on the collaborative strengths of the two companies, ensuring that VSL Hong Kong received a high level of service, professionalism and the best possible solution to meet their unique requirements.

THSR is a high-speed rail line that spans Taiwan’s west coast. Measuring approximately 345km in length, the rail line runs from Taipei Main Station in the north, to Kaohsiung in the South. Trains can reach a top speed of 300km/h and can complete the journey in approximately and hour and a half. Costing the Taiwan government a total of US$18 billion, THSR was one of the largest privately funded rail construction projects in the world.

Sections of the track were contracted for design and installation by VSL Hong Kong. VSL is a world leading specialist in construction engineering, associated technologies and services. VSL is particularly proficient in precast and segmental bridge erection projects. For THSR, VSL was instrumental in the design and construction of the many elevated sections of rail line.

These elevated sections were required due to Taiwan’s rugged and hilly terrain. For optimum performance, high speed-trains should operate on long, smooth and flat rail lines.

Due to this, THSR required the construction of multiple tunnels and long runs of elevated track. Altogether, 18% of THSR is comprised of tunnels, 73% is elevated and only 9% was built on the ground. The elevated tracks are held up by over 30,000 massive concrete supports. With so much of the track elevated, it is little wonder that THSR is one of the longest continuously elevated railways in the world.

In order to elevate the track, a segmental bridge design using precast concrete sections was employed. This method of bridge construction is economical where long spans (over 100 metres) of bridge is required. Segmental Bridges are built in short sections (called segments), that are hoisted into position one piece at a time. Each segment of the bridge must be attached to its predecessor. This connection must be secure and watertight, ensuring water cannot enter the bridges internal structure.

To achieve this watertight seal, a custom Expansion Joint was required. VSL Hong Kong was looking for an Expansion Joint that acted as an elastomeric gutter system, responsible for catching the rainwater that falls between the concrete sections and transporting it to the outside of the structure. The joint also needed to freely compress and expand to accommodate thermal movement and the dynamic interaction between the vehicle subsystem and the bridge subsystem. However, as Taiwan is highly prone to extreme earthquakes, VSL required the expansion and contraction range to be much greater than the standard range for Expansion Joints. It was specified that the joint must be able to compress to a width of 50mm and expand as wide as 350mm.

VSL specified that the material used must offer a 30 year life expectancy and have excellent physical properties including compression set, oil swell resistance, tensile strength, flexibility and more.
The task of designing and manufacturing this highly specified Expansion Joint was awarded to a joint venture between Boss Polymer Technologies and Granor Rubber. Working collaboratively, Boss and Granor developed two specialty, custom designed EPDM Expansion Joints.

The use of EPDM was not commonly seen in this type of Expansion Joint, which is traditionally manufactured from Neoprene. However, Neoprene could not offer the extended life expectancy VSL had specified. In order to achieve this, a speciality designed EPDM rubber compound was developed specifically for this project.

Once the material and design was tested and approved by the engineers at VSL Hong Kong, the Expansion Joint entered full production here in Australia. Over 15,000 lineal metres of Expansion Joint was produced, which filled several 40 foot containers. The manufacturing and export process ran smoothly and VSL were extremely satisfied with the product and customer service that they had received. The system has now been in place and performing as expected for over 10 years, without a single reported failure. The team at Boss are confident that the system will continue to perform for many more years to come.