It is called the winter solstice. This Friday will be the day of the year when the sun will be furthest from the northern hemisphere of the Earth, the day when natural light will therefore be shortest. No more than 8 hours and 18 minutes of daylight are in fact announced. And it won’t be much better the following days. A delicate period during which visibility on the roads becomes a major safety issue, especially in a context where most communities decide to reduce public lighting for environmental reasons and energy efficiency. Fortunately, several French manufacturers are trying to provide innovative responses.
This is the case of Colas and its system Flowell. This luminous ground marking makes it possible to illuminate pedestrian crossings or crossroads using thin slabs equipped with LEDs inserted into the roadway. Even more surprising, the system, connected to sensors, is triggered by itself when a road user arrives. “When they are turned off, the tiles are transparent. But as soon as they turn on, the scene changes, even in the middle of the day,” explains Etienne Gaudin, director of Flowell at Colas.
“We are aiming for around a hundred installations per year”
In testing since 2019, Flowell has benefited from official state approval since last summer for use on pedestrian crossings only. “The feedback is very positive. Pedestrians feel safer and motorists slow down. We were also able to measure that the compliance rate for the pedestrian crossing equipped with Flowell increased from 67% to 94%,” rejoices Etienne Gaudin.
“This technology can be beneficial to the extent that it reinforces the visibility of markings already in place,” observes Christian Sautel, project director within the Cerema, the public establishment having supervised the implementation of Flowell on behalf of the State. The dynamic side also opens up interesting perspectives for other use cases. However, it would be unnecessary and too expensive to equip all pedestrian crossings in cities. There are sites where the benefits are not obvious. You also need to be careful about light pollution. »
The installation cost is around 25,000 euros “turnkey”, according to Colas. Much more expensive than a traditional pedestrian crossing, but close to the cost of a pedestrian crossing equipped with lights. “Around ten passages have already been completed. In the medium term, we are aiming for around a hundred installations per year,” says Etienne Gaudin, who now hopes to obtain approvals for other cases.
“The strips light up at night for ten hours”
For its part, a Bordeaux company has been developing a so-called “photoluminescent” paint suitable for road marking for almost ten years. Its concept: it stores light rays during the day and releases them at night, like certain toys or decorative elements. “The painted strips light up in the dark for ten hours, without electricity or CO2 emissions. This creates a luminous, reassuring guide, visible up to 80 meters,” explains Jean-François Létard, founding director of the Olikrom company. Mostly tested on cycle pathsthe device called Luminokrom has also been the subject since the spring of a experimentation on a departmental road, at a dangerous bend, in Loire-Atlantique. “It’s amazing, we can see the lines very well in the middle of the night even if the slightly green result is surprising. The effect is really reassuring,” considers Christophe, 44, a local resident.
Also responsible for monitoring this experiment, which should last two years, Cerema is being more cautious. “The usefulness of the product remains to be demonstrated. Is the luminance (light perceived by the human eye) of the product really sufficient compared to that of the road illuminated by vehicle lights? Is it also sufficient throughout the night, depending on the clarity of the environment, the aging of the paint or its contamination? We need to produce results over time,” reports Jean-Noël Gaudin, engineer within the Lighting and Lighting research team at Cerema. “The darker the environment, the more spectacular the result will be,” recognizes Jean-François Létard, who affirms that his paint “resists very well to climatic hazards” and “to the passage of a million vehicles per year”.
The additional cost of this paint is also a factor to take into account, notes Cerema. It must be said that Luminokrom is, by its manufacturer’s own admission, “ten times more expensive” than a classic white paint. “This amounts to around 10,000 euros per kilometer including labor,” says Jean-François Létard. But if we compare to the bill for public lighting (between 200,000 and 400,000 euros per kilometer), it is very advantageous. »
“We come up against the heaviness of the administration”
In the meantime, Luminokrom has, unlike the Flowell device, received no approval from the State. Which has the gift of annoying the boss of Olikrom. “Our technology has been deployed on different testing grounds for five years, what are we waiting for? asks Jean-François Létard. We come up against the heaviness of the administration. I have around twenty communities waiting for a green light to put our paint on and cannot. The materials have evolved, taking advantage of them goes in the direction of history, especially if it is a French innovation. The regulations take too long to change. Is it better to leave people in the dark? »
“The procedures take time. As an entrepreneur, we would actually like things to go a little faster,” says Etienne Gaudin of Colas. “It’s true that it’s long but we’re talking about road safety,” objects Christan Sautel, from Cerema. The competent authorities are contacted by many organizations proposing technical developments. Ideas must be realistic, safe and proven before making a binding decision. »
Alongside Colas and Olikrom, other companies, such as Cryzal and its light and solar marking, are working on solutions to make the road more visible at night. “The systems currently in force on French roads are quite old,” recalls Etienne Gaudin. Reflective paint is perhaps the last major innovation and it is around fifty years old. New technologies are arriving and that’s good. I am convinced that they will develop. »