The primary aim of this study was to evaluate the effects of a new walking and cycling route on leisure-time physical activity (PA) (walking and moderate-to-vigorous PA) of adults. Furthermore, we also investigated the use, intention to use and barriers to use the new route for leisure-time PA. A longitudinal quasi-experiment was carried out. Three exposure groups were defined, based on the distance from home to the new route: 0–500 m, 501–1000 m and 1001–1500 m. Telephone-based interviews were carried out in 2009 and 2012. Those living around the new walking and cycling route increased their leisure-time walking by 15 min/week on average. Those residing up to 500 m from the route increased leisure-time walking by 30 min/week and walking plus moderate-to-vigorous PA by 50 min/week. The proportion of people who started walking or practicing moderate-to-vigorous PA during leisure time and who reported intention to use the new route was higher among those living closer to it. Perceived distance was the most prevalent barrier to use the new route.