Enhancing the Credibility of a 30 km/h Urban Speed Limit Through Road Design
T.A. Hogenstijn (TU Delft - Civil Engineering & Geosciences)
JA Annema – Mentor (TU Delft - Transport and Logistics)
Haneen Farah – Graduation committee member (TU Delft - Traffic Systems Engineering)
A. Maria Maria Salomons – Graduation committee member (TU Delft - Traffic Systems Engineering)
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Abstract
Dutch municipalities are increasingly reclassifying urban distributor roads from 50 km/h (GOW50) to 30 km/h (GOW30). For this policy to succeed, speed limits must be credible (i.e., aligned with drivers’ expectations formed by the visual and physical cues of the road). This study examines how road design features shape (i) actual vehicle speeds and (ii) drivers’ perceptions of speed limit credibility and safety. A mixed-methods design combined objective speed measurements from 30 urban road segments in the Netherlands (600 observations; 70% at 30 km/h) with a perception survey (n=83). For speeds, descriptive analysis, t-tests/ANOVA, and a General Linear Model (GLM) were used; perceptions were analyzed using chi-square tests and Ordinal Logistic Regression (OLR). Key results: (1) Narrower lanes, brick surfaces, and the absence of bike lanes are associated with lower speeds; (2) in multivariate GLM, road surface, lane markings, bike lane configuration, and lane width are significant predictors; (3) credibility perceptions differ by context: Features that bolster a 30 km/h limit include brick surfaces, absent markings, and minimal/no bike separation, while a 50 km/h limit is seen as more credible when presented with asphalt surfaces and clearer separation. The findings
provide empirical support for self-explaining road design and argue for design-led speed
management to reinforce low-speed policy goals.