The Driver Behaviour and Impact of Speed on Road Safety on the Motorways in Croatia

Zovak, Goran; Kos, Goran; Huzjan, Boris · 2017 · OpenAlex-citations

DOI: 10.7307/ptt.v29i2.2071

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Summary

This study investigates the relationship between driver speed compliance and road safety on Croatian motorways, specifically examining how Variable Message Signs (VMS) influence vehicle behavior. The research is motivated by the significant economic and human costs of traffic accidents in Croatia, where speeding is identified as the primary cause of fatalities. Despite improvements in road infrastructure and vehicle safety, excessive speed remains a critical issue, accounting for 40% of accidents on the Rijeka-Zagreb motorway. The study aims to determine the extent to which drivers respect static versus dynamic speed limits and to assess whether VMS can effectively reduce speeds to improve safety. The methodology involved a field study conducted between 2013 and 2015 on three distinct sections of the A1 and A7 motorways: a flat four-lane section (Location 1), a tunnel section (Location 2), and a city bypass with complex alignment (Location 3). Data was collected using video counters, recording over 300,000 vehicles. At Location 1, three scenarios were tested: a static limit of 130 km/h, a VMS limit of 100 km/h, and a VMS limit of 80 km/h. Locations 2 and 3 utilized static limits of 100 km/h and 60 km/h, respectively. The study analyzed average speeds, speed distributions, and compliance rates across these conditions to evaluate driver responsiveness to variable signage. The results indicate that driver compliance varies significantly by road geometry and signage type. On the flat motorway section (Location 1), few vehicles respected the static 130 km/h limit, with average speeds often exceeding 140 km/h during the day. However, the activation of VMS did influence behavior: reducing the limit to 100 km/h lowered the average speed by 6 km/h, while reducing it to 80 km/h lowered the average speed by 9 km/h. Despite these reductions, the average speed remained above the posted limits. In contrast, speed limits were exceptionally well respected in the tunnel (Location 2) and on the complex city bypass (Location 3), where drivers naturally adjusted their speeds due to the driving environment. The data confirms that while VMS can induce speed reductions, a significant portion of drivers on open, flat sections continue to exceed limits even when dynamic warnings are present. The study concludes that increasing respect for speed limits directly enhances traffic safety, but VMS alone is insufficient to ensure full compliance on straight, flat motorway sections. While VMS can influence a subset of drivers and produce positive changes in traffic flow, the majority of drivers on such sections do not strictly adhere to the signs. The authors recommend that additional measures, including repressive enforcement, are necessary to influence the group of drivers who ignore speed limits. The findings highlight the importance of combining technological interventions like VSL with stricter enforcement to effectively mitigate the risks associated with speeding on high-serviceability roads.

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Topics

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• speed choice
• speed management