Analysis of vehicle path radii on horizontal curves for two-lane rural roads

2021 ◽  
Author(s):  
Biljana Maljković ◽  
Dražen Cvitanić
Keyword(s):  
Rural Roads ◽  
Horizontal Curves ◽  
Vehicle Path

scholarly journals Speed Models for Motorcycle Riders for Two-lane Rural Roads

2021 ◽  
Vol 17 ◽  
pp. 595-603
Author(s):  
Panagiotis Lemonakis ◽  
George Botzoris ◽  
Athanasios Galanis ◽  
Nikolaos Eliou
Keyword(s):  
Prediction Models ◽  
Flow Speed ◽  
Operating Speed ◽  
Rural Roads ◽  
The Road ◽  
Horizontal Curves ◽  
Road Geometry ◽  
Speed Prediction ◽  
The Subject ◽  
On The Road

The development of operating speed models has been the subject of numerous research studies in the past. Most of them present models that aim to predict free-flow speed in conjunction with the road geometry at the curved road sections considering various geometric parameters e.g., radius, length, preceding tangent, deflection angle. The developed models seldomly take into account the operating speed profiles of motorcycle riders and hence no significant efforts have been put so far to associate the geometric characteristics of a road segment with the speed behavior of motorcycle riders. The dominance of 4-wheel vehicles on the road network led the researchers to focus explicitly on the development of speed prediction models for passenger cars, vans, pickups, and trucks. However, although the motorcycle fleet represents only a small proportion of the total traffic volume motorcycle riders are over-represented in traffic accidents especially those that occur on horizontal curves. Since operating speed has been thoroughly documented as the most significant precipitating factor of vehicular accidents, the study of motorcycle rider's speed behavior approaching horizontal curves is of paramount importance. The subject of the present paper is the development of speed prediction models for motorcycle riders traveling on two-lane rural roads. The model was the result of the execution of field measurements under naturalistic conditions with the use of an instrumented motorcycle conducted by experienced motorcycle riders under different lighting conditions. The implemented methodology to determine the most efficient model evaluates a series of road geometry parameters through a comprehensive literature review excluding those with an insignificant impact to the magnitude of the operating speeds in order to establish simple and handy models.

Relationship between Predicted Speed Reduction on Horizontal Curves and Safety on Two-Lane Rural Roads in Spain

2014 ◽  
Vol 140 (3) ◽  
pp. 04013015 ◽  
Author(s):  
Juan de Oña ◽  
Laura Garach ◽  
Francisco Calvo ◽  
Teresa García-Muñoz
Keyword(s):  
Rural Roads ◽  
Speed Reduction ◽  
Horizontal Curves

Speeds of Cars on Horizontal Curves

1998 ◽  
Vol 1612 (1) ◽  
pp. 42-47 ◽  
Author(s):  
Vojo Andjus ◽  
Mihailo Maletin
Keyword(s):  
Free Flow ◽  
Flow Conditions ◽  
Passenger Cars ◽  
Design Standards ◽  
Rural Roads ◽  
Horizontal Curves ◽  
Road Design ◽  
Realistic Approach ◽  
Actual Design ◽  
Design Speed

Revision of existing Yugoslav road-design standards, specifically in the area of road-design speed definition, required studying driver behavior in free-flow conditions in order to define drivers’ responses to the radii of horizontal curves. A specific approach with variable design speed for horizontal curves is discussed and is supported by speed measurements on roads. The pilot research was undertaken on several test sites on Yugoslav two-lane rural roads to collect reliable speed data related to characteristics of horizontal curves. Characteristics of test sites, experimental procedures, data collected, and results of data analyses are described. It is concluded that speeds of free-flow passenger cars show good correlation with radii and that actual design policy with a constant design speed underestimates speeds in radii less than 250 m. Thus, the variable design speed concept is a more realistic approach. Further research on more test sites is recommended.

The Effects of Edgeline Presence on Performance in a Driving Simulator under Sober and Alcohol-Dosed Conditions

1983 ◽  
Vol 27 (4) ◽  
pp. 329-329
Author(s):  
Thomas A. Ranney ◽  
Valerie J. Gawron
Keyword(s):  
Visual Information ◽  
Driving Simulator ◽  
Lateral Acceleration ◽  
Task Demand ◽  
Rural Roads ◽  
Pavement Markings ◽  
Horizontal Curves ◽  
Varying Length ◽  
Alcohol Effects ◽  
And Performance

Accident studies have identified nighttime conditions on rural roads as particular problems for alcohol-impaired drivers. Uneventful driving is hypothesized to result in progressive degradation of tracking performance and a reduced capability to handle the demands of hazardous locations, such as curves. To address these problems, simulations of continuous roadway treatments (i.e., wide edge lines) and spot treatments for curves (i.e., post delineators, chevron alignment signs, patterned pavement markings, and flashing displays) were evaluated experimentally. Twelve subjects drove a simulator under two conditions of task demand and three levels of BAC (0.0, 0.07, 0.12%). The objectives of the study were to determine the effects of alcohol and task demand on driving performance and to determine if providing enhanced visual information concerning roadway alignment would improve the performance of subjects when sober and/or alcohol-dosed. Alcohol effects were measured in terms of overall scenario performance, which included the number of accidents and speed exceedances, and performance on the approach and negotiation of horizontal curves of varying length and curvature. Curve approach and negotiation behavior were also used to evaluate the effects of the roadway treatments. Specific measures included spot measures of speed and lateral placement taken at eight 100-foot intervals along the curve approach and lateral acceleration and position taken continuously over the fixed portion of the curves. The results presented pertain to the effects of the presence of standard and wide edgelines. The discussion relates current findings to those from a previously conducted study.

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

2016 ◽  
Vol 11 (2) ◽  
pp. 127-135
Author(s):  
Biljana Maljković ◽  
Dražen Cvitanić
Keyword(s):  
Horizontal Curves ◽  
Percentage Difference ◽  
Friction Factors ◽  
The Difference ◽  
Design Speed ◽  
Vehicle Path ◽  
Design Consistency ◽  
Side Friction ◽  
Curve Radius ◽  
The Impact

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.

Evaluation of design consistency on horizontal curves for two-lane state roads using bicycle-model and realistic parameters of driver behaviour

2021 ◽  
Author(s):  
◽  
Biljana Maljković
Keyword(s):  
Point Mass ◽  
Horizontal Curve ◽  
Vehicle Model ◽  
Mass Model ◽  
Driver Behaviour ◽  
Horizontal Alignment ◽  
Horizontal Curves ◽  
Road Design ◽  
Vehicle Path ◽  
Design Consistency

The loss of vehicle stability in horizontal curves is a clear indicator of horizontal alignment design inconsistency, which can easily be quantified by determining the margins of safety. The doctoral thesis presents an overview of current horizontal alignment design guidelines and most important research of the design consistency concept. The following significant shortcomings in current road design practice were noticed: selection of unrealistic relevant speeds, the assumption that drivers follow a path with a radius equal to curve radius and the application of too simple vehicle model, i.e. basic point mass model. To overcome the observed limitations, the new consistent design approach has been developed, with an emphasis on horizontal curves. The new approach is based on the margin of safety concept, improved in terms of using the bicycle vehicle model in combination with more realistic values of speed and vehicle path radii. The bicycle vehicle model considers longitudinal load transfer, on individual axles, due to grade and speed changes, i.e. factors affecting margins of safety that are completely ignored by the simple point mass model used so far. To collect the driver behaviour data, an experimental investigation was conducted on a segment of the two-lane state road DC1 (Croatia). Individual speeds and vehicle path radii achieved by representative sample of drivers were recorded with a highfrequency GPS device. Based on the analysis of recorded data, the implementation of naturalistic driver behaviour in the road design process is proposed through regression models for predicting operating speeds (for tangents and horizontal curves) and through the equation for calculating the critical path radius. The improvement of the safety margin concept has created the basis for designing horizontal curves with high level of safety, both for the values of available friction on modern pavements as well as for future measurements. Based on operating speed consistency criterion and improved safety criterion related to driving dynamic consistency, the graphs of applicable adjacent horizontal curve radii were developed. The results obtained showed that the values of minimum horizontal curve radii need to be increased and, finally, this analysis has provided a physical explanation of the most common causes of accidents in sharp horizontal curves.

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