Cerema is assisting Colas in the development and testing of its innovative Flowell product, which responds to the need for active luminous road marking, not provided for in the present regulations. Flowell serves to reinforce existing light-signalling systems, and to provide public spaces with greater modularity. A number of experiments are already under way; others are under review.

Partenariat Cerema - société Colas - © Julien Gazeau

The need

Colas is a public works company specialised in building and maintaining the infrastructure that underpins transport and urban development.

It is developing an innovative road marking solution – Flowell – which consists of encapsulated LEDs glued directly onto the road surface. Flowell is designed to improve the safety of people using the space, with horizontal marking that lights up (active light-emitting signage). Thanks to dynamic lighting options, this new solution could also be used to alter the designated uses or users of certain road lanes at different times.

Colas entrusted Cerema with two missions in 2019:

  • provide scientific and technical support for the tests;
  • assess the visibility of the solution.

In addition, since 2020 Cerema has also been supporting Colas with the process of obtaining CE marking for innovative products. At local level, Cerema's regional divisions are required to conduct assessments with regard to some tests.

The partnership

By way of support for the tests, Cerema provides: expertise on defining the assessment protocols; analysis of how the protocols are implemented; scientific expertise regarding the test report.

The second mission is to determine a methodology for assessing the visibility of the Flowell product. The values of the photometric measurements traditionally used to quantify the visibility of objects within road infrastructure need to be adapted for this innovative product (active light-emitting road marking). An experimental platform has been set up at Cerema's site in Angers.

The Flowell solution opens up development potential for usage situations where the existing vertical or horizontal marking can offer no solutions. When the tests are complete, and depending on the assessment results for each site, active light-emitting road marking such as Flowell could be integrated in France's national regulations.

The innovation

The first tests were run in Mandelieu-la-Napoule, to the west of Cannes, in March 2019 (pedestrian crossings with active lighting). Then, in March 2020 in Nantes, a second test involved tracing bus trajectories on the road (with illuminated chevrons) and emphasising the traffic light stop line for other vehicles.

On 9 October 2020, an inter-ministerial order (amended on 30/07/2021) was published, authorising the testing of LED-based solutions like these for certain situations. Colas has run several experiments: pedestrian crossings in Paris; safeguarding active travel modes and guiding vehicles around La Défense's circular boulevard (Paris); safeguarding active travel modes in Nevers (central France).

Tests are due to be run soon on reinforcing safety at specific points (speed bumps, give ways, bus stops). In addition, studies are under way with a view to varying the designated uses or users of certain road lanes at different times.

As regards establishing a method for assessing Flowell's visibility, measurement work is in progress on the test site.

Partenariat Institut Carnot Clim'adapt et Colas


A partnership

Partenariat COLAS

A breakthrough to adapt to the effects of climate change or mitigate its causes

Emphasising road marking... changing the use of a public space at different times: for urban and rural areas alike, Flowell offers local authorities an alternative enabling them to use their infrastructure more effectively, and therefore optimise resources for better common usage of road spaces and safer active travel.


Institut Carnot Clim'adaptInstitut Carnot Clim’adapt is developing partnership-based research, i.e. management of research work conducted by public sector laboratories in partnership with socio-economic players, businesses of all sizes and local authorities, in order to meet their needs.
By making use of Cerema’s exceptional resources and regional coverage relating to research, engineering, expertise and equipment, Clim’adapt supports its partners to enable them to transition to a resource-efficient, carbon-free, environment-friendly economy, linked to new life styles engendered by digital transition and adaptation to climate change.
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