More and more people are cycling, a trend deemed to be good for public health. But statistics also show that the number of injuries from cycling have risen since 2010. Tackling the problem will probably mean a number of different solutions, one of which could be Viveca Wallqvist's soft asphalt.
Viveca Wallqvist is a scientist at SP, the Technical Research Institute of Sweden. She became interested in how road surfaces could be improved for cyclists and how to reduce injuries in the event of a fall in 2013.
"I was inspired by the materials used on playgrounds," she says. "They contain rubber from recycled tyres, and I began to research using similar material for bike paths."
Most cyclists are injured in solo accidents, and better paving should be able to reduce injuries. Her new 'bike asphalt', with rubber granules mixed in gives lower friction than normal asphalt, which reduces the risk of falling off, and is softer as well, reducing the risk of injuries if the worst happens.
"Rubber makes asphalt more absorbent," says Viveca, which reduces the risk of skin and skeletal injuries. You could describe it as building a form of protection into the path itself,
and scientists see a number of other benefits with rubber, such as an indication of lower ice formation. There are also hopes for lower risk of cracks in the paving and of punctures and wear on bike tyres. But they believe that the biggest potential lies in the reduction of the risk of injury whilst being able to recycle an under-utilised resource.
Research in progress
Introducing new material into asphalt mean new processes, such as pre-treatment. Rubber has previously been shown to break down bitumen, the binding agent used in roads, which weakens the asphalt. It therefore has to be pre-treated with bitumen before being mixed into the asphalt. Pre-treatment is one of the big issues being addressed in Viveca's research at this time.
"The problem is that no one sells bituminised rubber in Sweden at the moment. Which means the rubber has to be treated abroad, which is not ideal given the extra transport involved," explains Viveca. To be able to pre-treat in Sweden, we need more understanding of the process - and the equipment.
A fine material
Wallqvist sees benefits for the environment in being able to recycle such a fine material as tyre rubber instead of only using it as fuel, but also believes that controls will be needed as long as the market still has older tyres with outdated softeners. We also need to ensure that anyone working with the material does not encounter working environment problems.
"We are awaiting a report on the effects on the working environment from mixing rubber in asphalt," says Viveca. "The report has been delayed, but we hope that it will be published before the summer.
We have every reason to meet demand."