Research & Education
Jun 1, 2017
Bicycle trails that shine Bicycle trails that shine
Until relatively recently the materials that glow in the dark had no further functions beyond decorative pleasure. But the luminescence has been conquering more utilitarian applications and today, literally, it is in the streets.
The latest news in this respect comes from Poland. Last October was inaugurated in Lidzbark Warminski, a city to the north of the country, a small bike path that shines in the dark. It is a project carried out by TPA TPA Instytut Badan Technicznych Sp. z o.o and consists of the use of synthetic particles applied on asphalt, called luminophores - "phosphor compounds" - which are "recharged" by sunlight and at night emit a blue light for about 10 hours straight.
The Polish project was inspired by another bike path built between Eindhoven and Neuenen in the Netherlands in 2015 to mark the 125th anniversary of Vincent van Gogh's death. It was dubbed the "Starry Night" and its blue and green luminescent pontilistic effects arranged in spirals evoke the artist's painting. The author of the project was the Dutch designer Daan Roosegaarde and the company that made it was Heijmans. The principle used here appears to be similar to the one later used in Poland - the coating of asphalt still wet with a phosphorous substance - the photosensitive coating used, however, would have been other.
A suspended project
Before "Starry Night" Roosegaarde and Heijmans had been working together to achieve the concept of light roads. In 2014 they "illuminated" a section of about half a kilometer of the N329 motorway in Oss, 100km southeast of Amsterdam, using this kind of photoluminescent ink in the bands that limit it. The effect was that of bright green lines that glow for eight hours along the road as if it were neon.
The designer sought to understand the bioluminescence of jellyfish in an effort to reduce the need for energy expenditure and the ecological footprint. He was surprised by the hefty amounts spent on car research and development instead of the roads, which do shape the landscape and drew attention to the growing road lighting cuts that governments have promoted. He said that this was also an enterprise that was concerned with security.
While not disclosing the secret of the product, Roosegaarde said that it is a more evolved version of fluorescent paints that, in vain, only work for 30 minutes. In anticipation of the overcast climate of the Netherlands, the section of road in question had solar panels which, in turn, artificially charged the luminous stripes.
The Dutch project was, however, suspended shortly thereafter. The "ink" did not withstand the conditions of extreme humidity in the region and was being erased by the rains and the light bands became inconsistent.
The various paths to light
But Heijmans and the Dutch designer seem to not have given up and say they are working and testing a new version of the previous product. They also have in mind other projects such as roads that charge electric cars, paints in floors for warning signs that only appear in certain atmospheric conditions, illumination of the roads fed by the wind generated by car movement and the installation of cells that detect the approach of cars and activate the illumination of the road only for its passage.
In France, meanwhile, a section of road was coated with a type of asphalt that functions as solar panel, which allows its illumination and the public illumination of the nearest town.
As for the luminescent roads, the most significant advances seem to come from the other side of the globe, from Mexico, by the hand of engineer and researcher José Carlos Rubio. This scientist, together with a team of physicists and chemists, studied the composition of the asphalt and worked on the modification of its microstructure in order to allow the absorption of ultraviolet radiation by the silica (component present in the material). The project was tested, approved and 4 billion tons of this product were produced for commercialization.