Graffiti in pedestrian tunnels: A comparison of police records and crowdsourced data in Stockholm, Sweden

• Footways and stairway underpasses in the inner city contain most of the police records of graffiti. • According to app data, cycleway underpasses had the highest number of graffiti incidents. • Based on recorded incidents, pedestrian tunnels can be considered ‘risky facilities’. • Graffiti in pedestrian tunnels increases with tunnel size and proximity to the metro. • Managing graffiti in pedestrian tunnels and subsurfaces is key to urban sustainability. Using 1281 pedestrian tunnels scattered over Stockholm, Sweden’s capital, we investigate the nature and distribution of graffiti in three types of underpasses (pathways, cycleways, and stairways). Combining crowdsourced data and police records, we compare graffiti levels and geography using fieldwork inspections, regression models, and Geographic Information Systems (GIS). The findings indicate that graffiti recorded to the police is present in only a quarter of the pedestrian tunnels, suggesting that recorded practices are concentrated in specific underpasses. Graffiti is more commonly found in larger tunnels, particularly cycling underpasses. Proximity to metro stations, schools, and the presence of young males in the area are factors linked to graffiti occurrence, although not consistently. These results highlight the complexities of relying on graffiti records for public space management, particularly the challenges professionals face in aligning the maintenance of pedestrian tunnels with urban sustainability goals.