Background Few studies have evaluated environmental changes to promote physical activity. The impact of a local promotional campaign around a newly constructed Rail Trail in western Sydney, Australia, was assessed. Methods Pre and post-campaign telephone surveys were used. Adults 18–55 years of age were randomly sampled from an “inner” area, residents within ≤1.5 km of the Trail, and an “outer” area, bike-owners only, 1.5–5 km from the Trail. Objective concurrent monitoring of daily bike counts was carried out. Results A cohort of 450 completed both interviews. A significant increase (+2.9%, McNemar P < 0.05) in unprompted Trail awareness was detected but post-campaign awareness was low (34%). Inner cyclists, males, and those recalling any baseline bike promotion messages were more likely to be aware of the Trail. Trail usage was higher among bike-owners than pedestrians (8.9 vs 3.3%, P = 0.014) and was moderated by proximity to the Trail. Inner cyclists increased mean cycling time by 0.19 h (SD = 1.5) while outer cyclists decreased cycling time (−0.24 h, SD = 1.6). Mean daily bike counts in the monitored areas increased significantly after the Trail launch (OR = 1.35, P = 0.0001, and OR = 1.23, P = 0.0004). Conclusions The campaign reached and influenced cyclists in the inner area. For further increase in Trail usage promotional and educational programs focusing on walking for inner residents are needed.