Abstract
Cyclists must withstand significant wind force from passing vehicles. This study analyzed the magnitude of wind force generated by different vehicle types (sports utility vehicle, pickup truck, single unit truck, and semi-trailer truck), vehicle speeds (25, 40, and 60 mph), separation distances (2 ft, 4 ft, and 6 ft), and cyclist riding positions (racing and touring). Three research methods were used: field tests in controlled and natural environments, computational fluid dynamic simulations, and scaled-model wind tunnel experiments. The analysis focused on assessing longitudinal and transverse wind forces that are directed at the cyclist in parallel and perpendicular directions, respectively. All three methods showed the expected trend-that wind force increases with an increase in vehicle muzzle bluntness, vehicle speed, and cyclist proximity. Selected measurements and various models are provided. The wind force to knock a cyclist over (i.e., the flipping moment) was calculated for each test scenario (vehicle type, speed, and separation distance) and compared with the recommended limit (17 N) found in the literature. The semi-trailer truck generated flipping moments that exceeded the limit for all scenarios except 25 mph and 6 ft separation. All the vehicles, at all the speeds tested, exceeded the limit at 2 ft separation. This novel use of simulation and wind tunnel experiments provides groundwork for future research.