In 2014, the new wind farm Hartel 2 was built next to the national road N15 in Rotterdam. As the wind turbines stand closer to the edge of the road than imposed by the legal regulations and the rotor blades cross the road at particular wind directions, the Ministry of Waterways and Public Works had some doubts about the road safety of the drivers. A driving simulator study was carried out to check the impact on road safety. The project Hartel 2 got a go-ahead. But what is actually happening in day-to-day life? Do wind turbines distract drivers? Do they cause dangerous traffic situation? The Ministry gained science-based advice from IMOB.
IMOB studied how drivers reacted to the presence of wind turbines. The researchers compared speed, swinging behaviour and “near accidents” before and after the placing of the wind farm. They also investigated whether the position of the rotor blades (parallel to the road or crosswise) affect the driving behaviour differently. IMOB placed temporary cameras in streetlamps. Those cameras recorded 48 hours of visual material, which IMOB carefully analysed. Information about the travel time, the intensity and speed of through-traffic was measured by detection loops in the road.
Driving behaviour changes: lower speed and more left-sided positioning on traffic lanes
This study revealed two major changes in driving behaviour. First, drivers reduced their speed in the presence of the wind turbines. By day, an average speed reduction of 2,24km/h was recorded. At night, a speed reduction of 7,06 km/h was measured. Although IMOB noted a favourable effect, this study also indicated that not all drivers maintained even speeds. Some of them retained their speed, while other braked hard. Secondly, this study has shown that drivers positioned themselves – in the presence of wind turbines – more on the left side of the lane.
Both changes in driving behaviour can be problematic for road safety, but only if the differences are larger than the ones perceived in this study. The presence of the wind turbines had no effect on the “near accidents”.
Recommendation: no wind turbines near to traffic points that require high attention
Although no significant negative impact of wind turbines on road safety was shown, the researchers did find changes in driving behaviour. IMOB therefore recommends not to place wind turbines near to locations that require high attention, such as intersections, on-and-off-ramps, turns, pedestrian crossings, congestion-sensitive roads, etc.