Comparing Driver Behaviour with Measured Speed—An Innovative Approach to Designing Transition Zones for Smart Cities

Speed limits are widely used in transition zones between rural and urban areas, where road and environmental conditions change and drivers are expected to reduce their speed. These locations often generate particularly complex driver behaviour in response to applied traffic calming measures (TCMs). Previous studies have mainly focused on the effectiveness of individual TCMs in reducing speed; however, analyses directly comparing drivers’ declared behaviours with actual measured speeds remain limited. The aim of this study was to assess the effectiveness of selected TCMs—chicanes, central island, refuges island, and dynamic speed feedback signs (DSFSs)—across 26 transition zones, taking into account land-use characteristics, driver fixation points, and the road’s visual perspective. To evaluate consistency or discrepancies, the declared behaviours of survey respondents assessing these locations were compared with speed measurements collected from other drivers travelling through the same zones. The analyses help define the relationship between drivers’ perception and their actual behaviour, identifying which TCMs, when combined with specific road-environment features, are most effective in achieving the target speed of 50 km/h in built-up areas. The most effective chicanes proved to be those with the greatest width (2.5 m), i.e., almost equal to the width of a traffic lane, as well as those with a width of 2.0 m combined with a change in pavement surface from asphalt to stone paving, or those located upstream of a road section characterised by high curvature and limited visibility. In contrast, symmetrical islands, even with a width of 3.0 m, were found to be completely ineffective. The findings support the development of more effective transition-zone design principles and provide guidance for future mobility strategies, including the integration of automated vehicles in smart cities.