Field Study of Pedestrian Crossings Deterioration Over Time: Assessment of Microplastics Emission from Road Markings

Abstract The issue of road marking deterioration (loss of functional properties, followed by abrasion) is of profound importance, so appropriate maintenance of roadway infrastructure is required. When road markings are used past their intended functional service life, they can undergo abrasion, which negatively affects their visibility for drivers and also leads also to emission of microplastics. This study was undertaken to fill the knowledge gap related to the rate and extent of abrasion that could be expected from road markings exposed to heavy traffic after the loss of functional properties. Analysis of luminance loss over three years was utilised as an indirect measurement method. The outcome, based on assessment of three pedestrian crossings, indicated average abrasion of 2.1% per 1 million weight-adjusted vehicle passes when cold plastic, a durable material containing hard coarse fillers, was used. However, it could exceed 20% if paint, unsuitable for such jobs, was utilised instead. Thus, the polymer quantities released from the analysed zebra stripes during the three years of usage past their functional service life varied from 10.3 to 25.9 g per 1 million weight-adjusted vehicle passes. Such relatively large measured abrasion and emissions was a result of grossly negligent maintenance. Hence, appropriate selection of materials for a particular road and their correct maintenance were shown as necessary to not only assure visibility of the road markings for drivers, but also to minimise the emissions to minimise the environmental impact.