Review of tools for road runoff quality prediction and application to European roads

Pollutants discharged by roads may impact water bodies and soils. The best method to characterise road runoff is by monitoring, which is not always possible due to human or material constraints. Therefore, prediction tools can be a valuable method to manage road runoff discharges and protect the environment. The present work reviewed and evaluated international tools for road runoff quality prediction, in order to assess if an existing tool could be suitable for wide usage by stakeholders in Europe. Four tools from the USA and Europe were selected and tested at 22 road sites located in regions with annual precipitation values ranging from 500 to 1,000 mm, from seven European countries. The results for the site median concentration (SMC) of total suspended solids (TSS), Zn, Cu, Pb and Cd showed coefficients of determination (R2) from 0.0004 to 0.2890 for the different pollutants and tools. It was concluded that none of the tools could predict the road runoff pollutant concentrations, except for the country where it had been calibrated. The findings support practitioners and researchers all over the world, pointing out directions, and gaps to be filled, regarding the management of road runoff discharges and use of prediction tools.