Mission impossible: can the world’s longest bicycle tunnel increase cycling in a rainy and hilly city?

In 2023, the world’s largest bicycle tunnel opened in Bergen, Norway’s second-largest city. In addition, a 7.9 km long bicycle highway opened as part of the road network linking the residential area Fyllingsdalen with Bergen city centre. This study investigates two key research questions related to this infrastructure project. First, to what extent does such a tunnel improve access to urban areas for residents? Second, has the tunnel caused more cycling? To address these questions, we analysed data from a two-wave survey conducted both before and after the tunnel’s opening. Our findings indicate that the tunnel substantially reduces cycling times to key hubs, particularly for those living close to the tunnel entrance, where travel times decrease by more than 15 min (approximately 40 percent). This benefit diminishes rapidly for individuals residing outside this immediate radius. Our difference-in-difference analyses show that the tunnels indeed caused more cycling. In areas with large reductions in cycling time to key hubs, we observe treatment effects of up to 5 percentage points in cycle shares. These behavioural effects are strong, not least because the tunnels are built in a city where weather and topography discourage cycling.