BITSDRAIN: Porous Bituminous Pavements for Sustainable Urban Drainage

Urban expansion has disrupted the natural hydrological cycle by limiting rainwater infiltration and evapotranspiration. As a result, surface runoff has increased, aquifer recharge has decreased, and flood risks have grown. This situation is worsened by climate change, which increases the frequency of intense rainfall events that traditional urban drainage systems are often unable to cope with.

In this context, Sustainable Urban Drainage Systems (SUDS) are gaining relevance, as they integrate nature-based solutions and permeable infrastructure, such as green roofs, infiltration trenches, or permeable pavements. The latter allow water to pass through their porous structure, mimicking natural drainage processes. This slows down the flow, enables temporary water storage, and helps flatten runoff hydrographs, contributing to more efficient water management in urban areas.

Permeable pavements also help improve water quality by promoting infiltration into underground layers. BITSDRAIN focuses specifically on porous bituminous mixtures, which are still rarely used in urban environments, despite their widespread application in road infrastructure to improve safety in wet conditions. Their incorporation in large urban areas —such as bike lanes or pedestrian zones— could support a more natural and resilient drainage model.

The project is based on the hypothesis that porous bituminous pavements can store water within their structure and convey part of the surface flow, reducing its velocity and increasing the time of concentration. This could help mitigate peak flows during storms, reduce flood risks, and ease the burden on sewer systems.

BITSDRAIN includes experimental tests using a scaled physical street model. The simulation tool developed will later be validated using a real case study, allowing the modelling of infiltration and transport processes within the pavement and serving as a basis for future technical recommendations.

The impact of the project will be twofold: technical and social. BITSDRAIN will provide a useful tool to quantify the effect of applying porous asphalts in urban areas and to assess their influence in reducing flood risk. Its implementation can represent a major step forward in sustainable urban planning, benefiting municipalities, engineering firms, public services, and society at large by contributing to the creation of safer, more resilient cities prepared to face the challenges of climate change.

Budget and Funding

The project has a total budget of €801,000, funded through the Spanish State Plan for Scientific and Technical Research and Innovation 2021–2023 (State Research Agency), and will run for 36 months (November 2023 – October 2026).