Development of a local operating speed model for consistency analysis integrating laser, GPS and GIS for measuring vehicles speed

Castro, María; Pardillo-Mayora, José María; Jurado, Rafael

doi:10.3846/bjrbe.2013.36

Cited by 10 publications

(9 citation statements)

References 13 publications

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“…Complementary fits were then carried out using uncorrected data, introducing the year and the speed limit as explanatory variables. Castro et al (2013) developed an operating speed model for passenger cars on circular curves collecting data on 42 elements of two-lane rural highways in South-West Spain integrating laser, GPS and GIS systems. They made a comparison between this model and several models developed previously in other European countries.…”

Section: Introduction and Literature Reviewmentioning

confidence: 99%

Operating Speed as a Key Factor in Studying the Driver Behaviour in a Rural Context

2016

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The research aims to explore the effects of geometric road features on driver speed behaviour in order to identify unsafe road segments where high reductions in speed between successive road elements occur. The sample involves two-lane rural roads on flat terrain (vertical grade less than 5%) in Southern Italy, totalling 184 km without spiral transition curves between the tangent segments and circular elements. The testing was carried out on 567 study sites, of which 248 are on circular curves and 319 on tangents. Speed data collection was carried out in environmental and traffic conditions using a laser. The conditions were the following: dry roads, free flow conditions, daylight hours and good weather conditions. The main goal was to calibrate and validate different operating speed prediction models: a) one model on tangent segments; b) one model on circular curves; c) only one model to be used at the same time on tangents and circular curves. The validation process involved almost 10% of the total road network length, that was removed from the calibration phase. The speed measurements of each of the first two datasets (a, b) were grouped into ten homogeneous substrates while for the remaining dataset (c) sixteen substrates were defined by using a hard c-means algorithm. Two statistical criteria were used to remove anomalous operating speed values from each group of three datasets, namely, the Chauvenet criterion and the Vivatrat method. The first criterion was preferred in the final process of model selection. The results of the first filtering procedure showed more homogeneous samples that guaranteed a higher correlation coefficient and lower residuals of the predictive models during the validation phase than the Vivatrat method. The models were developed using an Ordinary Least Squares (OLS) method. The explanatory variables were total segment length, lane width, curvature of the road element, the curvature change rate on homogeneous road segments, and the number of residential driveways per km. ANOVA and additional synthetic statistical parameters were assessed to check the effectiveness of using a single general model to predict operating speeds at the same time on tangents and on circular curves alike. The results suggested the reliability of this hypothesis and its effectiveness in bringing advantages during the application phase.

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Section: Introduction and Literature Reviewmentioning

confidence: 99%

Operating Speed as a Key Factor in Studying the Driver Behaviour in a Rural Context

2016

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“…One way to accommodate to human information processing limitations is to design roadway environments by driver expectations: the design of a road in according to the standards and, consequently, reflecting the expectations of drivers, creates a proper alignment consistency (HSM 2010). Castro et al (2013), Morris and Donnell (2014), Russo et al (2015;2016) have verified the operating speed as one of the parameters to most influence a safe driving. One of how operating speeds are used in ensuring design consistency is using speed profiles.…”

Section: Introductionmentioning

confidence: 94%

Countermeasures to Improve Road Alignment Consistency Of Undivided Rural Roads

Russo

Biancardo

2017

The Baltic Journal of Road and Bridge Engineering

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The research aims to assess the relationships between the crash rates and road consistency. Design consistency assessment is a tool employed by designers to improve road safety. The case study involved a rural two-lane two-way road in Southern Italy located on a flat terrain without spiral transition curves between tangent segments and circular curves. Road alignment consistency was examined in two steps: by adopting standards in force in Italy based on the design speed profile and by plotting operating speed profile to determine the area bounded by the speed profile and the average weighted speed, and the standard deviation of operating speeds for each geometric segment. Operating speed prediction model, which returns the 85th percentile of the speed distribution of the only cars under free flow conditions, right weather conditions, and lighting was adopted. A negative exponential function was performed to predict the global consistency of a road as a whole. Finally, a model for predicting the crash rate was calibrated, confirming an increase of design consistency when the crash rates decrease significantly. The consistency model represents a useful tool during the geometric design process or the evaluation process for two-lane rural highways.

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“…Certainly, one of the most commonly used and most effective strategies to improve road safety is road design consistency. It is defined as the condition in which roadway geometry does not violate driver expectations (Castro et al 2013). A consistent road design implies logically arranged successive elements that produce consistent speeds and do not require abrupt actions which increase the accident occurrence.…”

Section: Evaluation Of Design Consistency On Horizontal Curves For Twmentioning

confidence: 99%

“…The most frequently used design consistency criteria are based on operating speed because the changes in operating speed are obvious indicators of design alignment inconsistencies (Nicholson 1998;Castro et al 2013). These measures include the design speed and operating speed consistency for a single geometric element and consistency of operating speeds within one road section (Lamm et al 1995).…”

Section: Evaluation Of Design Consistency On Horizontal Curves For Twmentioning

confidence: 99%

“…These measures include the design speed and operating speed consistency for a single geometric element and consistency of operating speeds within one road section (Lamm et al 1995). Operating speed is usually defined as 85 th percentile speed and many operating speed models have been developed in different regions of the world (Castro et al 2013;Modeling Operating Speed: Synthesis Report 2011).…”

Section: Evaluation Of Design Consistency On Horizontal Curves For Twmentioning

confidence: 99%

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Evaluation of design consistency on horizontal curves for two-lane state roads in terms of vehicle path radius and speed

Maljković

Cvitanić

2016

The Baltic Journal of Road and Bridge Engineering

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Experimental investigation was conducted on a 24 km long segment of the two-lane state road to collect the driver behavior data. The research involved 20 drivers driving their own cars equipped with the GPS device. Considering the impact of path radius and speed on the side friction demand, the design consistency on horizontal curves was evaluated by determining the margins of safety. The analysis showed that the vehicle path radii were mainly smaller than curve radius, on average for 12%. Regression analysis indicated that the percentage difference between the curve radius and vehicle path radius is not affected by the speed, speed differential and geometric characteristics of the curve and surrounding elements. Two different margins of safety were analyzed. One is the difference between maximum permissible side friction (based on design speed) and side friction demand, while another is the difference between side friction supply (based on operating speed) and side friction demand. Generally, demands exceeded supply side friction factors on curves with radii smaller than 150 m, whereas “poor” conditions (in terms of Lamm’s consistency levels) were noted for curves under approximately 220 m. Both values are very close to the critical radius below which higher accident rates were observed according to several accident studies. Based on the results of the research, it is proposed to use a 12% smaller curve radius for the evaluation of margin of safety and that curves with radii smaller than 200 m should be avoided on two-lane state roads outside the built-up area.

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Development of a local operating speed model for consistency analysis integrating laser, GPS and GIS for measuring vehicles speed

Cited by 10 publications

References 13 publications

Operating Speed as a Key Factor in Studying the Driver Behaviour in a Rural Context

Operating Speed as a Key Factor in Studying the Driver Behaviour in a Rural Context

Countermeasures to Improve Road Alignment Consistency Of Undivided Rural Roads

Evaluation of design consistency on horizontal curves for two-lane state roads in terms of vehicle path radius and speed

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