New research on road sign visibility paving the way towards safer traffic

Road signs that are clear and visible are important for safe and efficient road traffic. They warn of dangers, provide information about rules, and offer guidance. New research provides insight into the lifespan, visibility, and importance of road signs for road safety.

In her recently published thesis, Roxan Saleh, a doctoral student at Dalarna University, specialised in research in machine learning of road signs. By analysing extensive data sets from different road signs, she investigated how retroreflection and colour gradually deteriorate over time and how this affects their visibility. Data was collected from Sweden, Croatia, and Denmark, and then an evaluation was conducted as to how well road signs retain their properties over time and under different environmental conditions.

– With Machine learning models, we can predict and optimise road sign maintenance more efficiently. An increased understanding of the lifespan and visibility of road signs will enable us to create safer roads for everyone," explains Roxan Saleh, who has a Master of Science in Building and Construction Engineering Specialized in Structural Engineering.

Roxan has combined her doctoral studies with her role as a road equipment specialist at the Swedish Transport Administration. This means that the results of her research can directly benefit the development of safe and sustainable road signs. The results are important not only for traffic authorities and decision-makers, but also for the safety of road users and the well-being of society.

The models can be crucial when it comes to updating rules regarding the design and maintenance of road signs. This can lead to improved road safety through improvements in the design, lifespan, and visibility of road signs.

– These predictive models can replace the traditional methods used to measure retroreflectivity and colour chromaticity, which are costly, and time-consuming. The new insights can also contribute to improved maintenance strategies and increased safety in urban development and infrastructure projects," says Roxan Saleh.

Facts: Lifespan and visibility of road signs

• Colour and retroreflectivity plays a key role in the visibility of road signs. Using an adequate type of retroreflective sheeting can significantly improve night visibility.
• The median lifespan, based on retroreflectivity, of road signs in different colours varies. In Sweden, it can be from 16 years for red to 45 years for yellow road signs.
• In Croatia, road sign lifespans, as determined by retroreflectivity, are shorter compared to those in Sweden, highlighting the necessity for earlier maintenance.
• The use of machine learning to predict the degradation of road signs opens up for more efficient and cost-effective maintenance strategies.

Read the thesis: Towards Smart Maintenance : Machine-Learning Based Prediction of Retroreflectivity and Color of Road Traffic Signs (diva-portal.org)