Sustainable road markings for sustainable urban mobility – selection guidelines based on environmental and durability parameters

Proper organisation of road transport path is required for the mobility efficiency, for the comfort of road users, and for safety. Road markings are inexpensive road infrastructure features that make road transport easier and safer; their proper selection is very important. For the use in cities, materials must be durable, provide high-friction surfaces for unprotected road users, and be characterised by minimised emissions of volatile organic compounds, low carbon footprint, and curtailed microplastic and particulate emissions. Enhancement of nighttime visibility is usually less important because of external illumination. Because road markings are deteriorating systems, it is necessary to consider all of these requirements from a long-term perspective that includes multiple renewals. To provide materials selection guidelines, several commonly utilised in Europe types of road markings were compared. Durability was assessed based on field measurements of functional properties and evaluation of erosion (i.e. complete abrasion and removal from the roadway surface that results in the release of microplastics), sometimes extrapolations were necessary. The extent of various types of potential emissions was then assessed and global warming potential was calculated. Several parameters, notably skid resistance, had to be excluded because data was either impossible to quantify or absent; uncertainty in the life cycle assessment calculation that could reach even 30% because of its known fallacies should be noted. The outcome demonstrated that the utilisation of road markings that provided the longest service life was the best choice from the assumed long-term perspective; thus, the claim that ‘sustainability is durability’ was supported for the nth time. Specifically, road markings made with cold plastic can be indicated as the most suitable and sustainable for the use in urban spaces at heavily trafficked areas because of their low propensity to abrasion (hence, minimised microplastic and particulate emissions), intrinsic high skid resistance, low emissions, and low overall carbon footprint.