Modeling speed limit compliance in shared spaces

While shared spaces (also known as shared zones) encourage interaction among road users, non-compliance with posted speed limits is a key safety concern. Most research concerning drivers' speeding behavior in shared spaces has predominantly centered on descriptive analyses and statistical testing, neglecting to account for the effects of shared space features, vehicle types, and traffic characteristics on speeds. As a result, there exists a significant knowledge gap regarding how the attributes of shared zones, surrounding traffic, and vehicle platoons impact driver speeds.

Speed data from two shared spaces in Australia were analyzed using left-censored Tobit regression models (non-compliant: continuous, compliant: zero) to assess drivers' compliance with posted speed limits.

Results showed that the magnitude and probability of speeding were significantly reduced by the number of conflicts involving the vehicle and the provision of parking spaces in shared spaces. Conversely, vehicles such as cars, two-wheelers, and those with surrounding vehicles speeding exhibited lower compliance probabilities, while heavy vehicles and those following them showed higher likelihoods of compliance. However, the time of day or day of week had no significant influence on drivers' speeding behavior, indicating consistent traffic interactions and compliance behaviors throughout the week.

This study identifies key factors influencing speeding behavior in shared spaces and provides insights for identifying countermeasures and promoting safer interactions.

The findings can help urban planners and policymakers set appropriate speed limits, develop better shared space designs, and enhance safety for all users, particularly those who are the most vulnerable.