Predictable motorway ramp curves are safer

Motorway safety depends largely on curve geometry and driver behaviour, a relationship that has implications for research and practice. This paper introduces a novel approach to quantifying geometric design consistency, defined as the degree to which drivers’ expectations of curve radii match actual...

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Main Author: Johan Vos
Format: Article
Language:English
Published: Elsevier 2025-07-01
Series:Transportation Research Interdisciplinary Perspectives
Subjects:
Online Access:http://www.sciencedirect.com/science/article/pii/S2590198225002015
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author Johan Vos
author_facet Johan Vos
author_sort Johan Vos
collection DOAJ
description Motorway safety depends largely on curve geometry and driver behaviour, a relationship that has implications for research and practice. This paper introduces a novel approach to quantifying geometric design consistency, defined as the degree to which drivers’ expectations of curve radii match actual road geometries. The hypothesis is that if a driver expects a larger curve than that actually present, an accident might occur because of an excessively high approach speed. To test this hypothesis, this study uses Dutch motorway data, including ramp and curve characteristics, as well as crash frequencies. The data were employed in three steps: 1) constructing a Bayesian model that mimics drivers’ expectations, 2) testing the predictions of this model against real curve characteristics, and 3) examining the relationship between disparities in expectations, reality, and crash frequency. The results indicated a positive correlation between disparities in expectations, reality, and crash frequency. This finding suggests that the crash frequency is higher when drivers expect a larger curve than what is present. The Tree Augmented Naïve Bayesian Network (TAN) reveals the complexity of curve expectations, demonstrating that drivers anticipate larger radii in connector ramps and higher speeds with gentler curve angles. Applying this research to motorway design involves using TAN predictions and crash frequency models to assess safety in motorway curve design, which could proactively improve road safety.
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spelling doaj-art-edf63bb4ca614d1bb330908fc4e4678c2025-08-22T04:57:49ZengElsevierTransportation Research Interdisciplinary Perspectives2590-19822025-07-013210152210.1016/j.trip.2025.101522Predictable motorway ramp curves are saferJohan Vos0Department of Transport and Planning, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Stevinweg 1, 2628 CN Delft, the NetherlandsMotorway safety depends largely on curve geometry and driver behaviour, a relationship that has implications for research and practice. This paper introduces a novel approach to quantifying geometric design consistency, defined as the degree to which drivers’ expectations of curve radii match actual road geometries. The hypothesis is that if a driver expects a larger curve than that actually present, an accident might occur because of an excessively high approach speed. To test this hypothesis, this study uses Dutch motorway data, including ramp and curve characteristics, as well as crash frequencies. The data were employed in three steps: 1) constructing a Bayesian model that mimics drivers’ expectations, 2) testing the predictions of this model against real curve characteristics, and 3) examining the relationship between disparities in expectations, reality, and crash frequency. The results indicated a positive correlation between disparities in expectations, reality, and crash frequency. This finding suggests that the crash frequency is higher when drivers expect a larger curve than what is present. The Tree Augmented Naïve Bayesian Network (TAN) reveals the complexity of curve expectations, demonstrating that drivers anticipate larger radii in connector ramps and higher speeds with gentler curve angles. Applying this research to motorway design involves using TAN predictions and crash frequency models to assess safety in motorway curve design, which could proactively improve road safety.http://www.sciencedirect.com/science/article/pii/S2590198225002015Motorway curvesRoad safetyDriver expectationsBayesian Belief ModelCrash frequency
spellingShingle Johan Vos
Predictable motorway ramp curves are safer
Transportation Research Interdisciplinary Perspectives
Motorway curves
Road safety
Driver expectations
Bayesian Belief Model
Crash frequency
title Predictable motorway ramp curves are safer
title_full Predictable motorway ramp curves are safer
title_fullStr Predictable motorway ramp curves are safer
title_full_unstemmed Predictable motorway ramp curves are safer
title_short Predictable motorway ramp curves are safer
title_sort predictable motorway ramp curves are safer
topic Motorway curves
Road safety
Driver expectations
Bayesian Belief Model
Crash frequency
url http://www.sciencedirect.com/science/article/pii/S2590198225002015
work_keys_str_mv AT johanvos predictablemotorwayrampcurvesaresafer