Road markings are materials bonded to, or embedded in, pavement surfaces, mainly roads, parking lots and airport runways, to convey official information, particularly regarding lanes, speed limits, stopping, authorized vehicle types, crosswalks, railroad crossings, turns, travel direction and parking spaces. In addition to providing visual information they are also sometimes designed to produce noise, vibration or illumination, such as raised lane markings that alert drivers that they are drifting into another line or onto road edges. The most commonly used materials are hot-melt paints, which are a mixture of a plastic binder, pigments, and various other materials.
Although road markings are extremely important for transportation safety and efficiency, they are also a large and growing source of environmental pollution. This is because of the vast, and ever-increasing, amount of such materials in use worldwide together with their continuous abrasion by automobiles and other road vehicles as well as from weathering.
The resulting tiny particles can become airborne and travel in the air for considerable distances. They also enter water bodies both from the air and from being washed there by rain, where they not only pollute the water but are also ingested by fish and other aquatic animals and thereby enter the food chain.1
One way to mitigate this problem is to use embedded studs or colored paving blocks instead of painted markings. Another would be to encourage the use of lighter weight vehicles in order to reduce abrasion. This has the additional benefits of reducing fuel consumption, reducing road damage, and reducing injuries to pedestrians. 2
A much more effective solution would be to greatly reduce the use of all types of road markings by reducing the amount of land that is paved for roads and parking lots while also reducing the number of road vehicles. Although this might initially seem drastic, it can be the most logical solution when considered together with the very large role that mass road transport is having in the current environmental emergency.
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1. See, for example, https://www.independent.co.uk/ climate-change/news/ microplastic-paint-pollution-rivers-lakes-road-markings-yellow-lines-a7340071.html.
2. Reducing vehicle weight is incompatible with the goal of increasing the use of battery-powered electric vehicles, which are generally much heavier than comparable internal combustion engine vehicles because of the great weight of the batteries. However, it is not clear that there is really any major environmental advantage to a mass conversion from internal combustion engine vehicles to electric vehicles. See, for example, Electric Vehicle FAQ.