Archive

The rubber highways consist of panels made from shredded car tyres held together by a polyol-based binder that are laid over existing railway tracks. The system has been designed to be easy to install, and at significantly lower cost than building an equivalent new road. The new routes could provide one-way relief roads for peak hour traffic and could be shared by cars and trams travelling at speeds of up to 50 mph.

Similar hardwearing panels, produced by Rosehill Polymers, have been widely employed around the world at level crossings, where a road crosses a railway, and have helped to reduce maintenance and extend crossing lifespan.

"Rubber panels absorb shock to the rail bed better than concrete and are quick to install, reducing expensive track closure time and service disruptions," says Stuart Wilson, the company's Sales Manager.

"We have invested significantly in the development of the rubber and binder process over the last five years as interest from rail networks around the world has grown, in order to ensure the panels have the right final properties."

The concept has now been extended by developers HoldFast to create an opportunity for producing cost-effective interlocking panels that can be laid on the gaps between rails on disused railway lines.

HoldFast Managing Director Peter Coates-Smith, believes the Holdfast Rubber Highway (HRH) could create an achievable multi-user transport solution. "There is a real need for new and affordable options to realise infrastructure opportunities. This system offers a way to rejuvenate redundant rail lines and loss making community lines into toll lanes for several types of vehicles.

"As the panels are designed to be laid on routes originally intended for trains, they are also ideally suited for trams or guided buses, which could run on the rails left exposed between the rubber mats."

In addition to initial build costs, he says that maintenance costs are also much lower with the flexible highway. "There are no potholes, cracking or spoiling from the effects of frost, and individual panels can be replaced in less than ten minutes. It's also a very quiet surface."

He believes that eventually the system could be used to build a network using redundant lines as an alternative to urban bypasses and routes into major conurbations. And because no alterations are made to the track bed or rails, the lines can be easily reinstated.

A demonstration track has been on trial for nearly a year on a branch line leading into a car depot in Northamptonshire. The rubber highway is used to transfer cars from trains into the depot and handles a very high volume of traffic.

The trial has been funded by WRAP (Waste and Resources Action Programme), a UK Government-backed initiative established to promote resource efficiency.

The rubber highway concept has two strong recycling aspects. Firstly, it is based on the use of existing derelict city centre rail tracks as one-way roads for vehicles. Secondly, the HoldFast panels are made with recycled rubber, which could provide a use for some of the estimated 50 million tyres disposed of in the UK alone each year.

EU legislation prohibits sending tyres to landfill sites or burning them, making alternative uses like this more attractive. Around 350,000 tyres would be recycled in a one mile stretch of rubber highway.

Rosehill Polymers currently recycles over 4,000 tonnes of used rubber annually - the equivalent of one million car tyres. Some ten million tyres have been used in rubber crossing platforms since 1999.

The pre-polymer used for the binder that holds the rubber granules together, and gives the panels the necessary elasticity and tensile strength, is based on CARADOL* polyols from the Shell Chemicals CASE (coatings, adhesives, sealants and elastomers) grade range.

Around 50 percent of the binder Rosehill produces is exported, and is responsible for re-bonding an additional 45,000 tonnes per year of recycled rubber for sports pitches, playground surfaces and compression moulded products.

CARADOL content

The rail crossing panels, weighing a quarter of a tonne each, are produced by compressing the granules and binder mix in a 2000 tonne press.

Because the binder is ambient cure, it reduces the energy used. "Traditional re-vulcanising involves heating the rubber to 160°C in a process that can take up to 16 hours," explains Wilson. "Getting heat into a panel this size also requires huge amounts of energy. Using a moisture-curing polyurethane binder in a fully automated process means we can produce panels in less than 30 minutes with minimal energy."

The panels have to conform to the strict specifications of rail networks, with defined tolerances for abrasion and skid resistance. "They have a life expectancy of around 15 years but once they come to the end of their useful life, they can be chopped up and recycled again," he adds.

The feasibility of the rubber highway is still being assessed but a number of companies, transport authorities and local authorities have expressed interest in the technology. The developers believe its environmental advantages and congestion-beating potential will make it a success.

Rosehill Polymers website - opens in new window

HoldFast Rubber Highway website - opens in new window

• Playing to our strengths
• Going with the flo
• Storage standards
• Trading places
• Technology for tomorrow's world
• Mixed wash
• Solvent solutions to VOCs