scholarly journals COUNTERMEASURES TO IMPROVE ROAD ALIGNMENT CONSISTENCY OF UNDIVIDED RURAL ROADS

2017 ◽  
Vol 12 (4) ◽  
pp. 211-217 ◽  
Author(s):  
Francesca Russo ◽  
Salvatore Antonio Biancardo
Keyword(s):  
Evaluation Process ◽  
Weather Conditions ◽  
Operating Speed ◽  
Speed Profile ◽  
Negative Exponential Function ◽  
Crash Rates ◽  
Consistency Model ◽  
Global Consistency ◽  
Design Consistency ◽  
Circular Curves

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.

Time-Based Calibration of the Inertial Operating Speed to Enhance the Assessment of the Geometric Design Consistency

2018 ◽  
Vol 2672 (38) ◽  
pp. 223-232 ◽  
Author(s):  
David Llopis-Castelló ◽  
Francesco Bella ◽  
Francisco Javier Camacho-Torregrosa ◽  
Alfredo García
Keyword(s):  
Human Factors ◽  
Short Term Memory ◽  
Weighted Average ◽  
Geometric Design ◽  
Accurate Estimation ◽  
Operating Speed ◽  
Speed Profile ◽  
Consistency Model ◽  
Global Consistency ◽  
Design Consistency

Road crashes are mainly caused by three concurrent factors: infrastructure, vehicle, and human factors. The interaction between the infrastructure and human factors leads to the concept of geometric design consistency. Recently, a global consistency model was developed based on the difference between the inertial operating speed profile and the operating speed profile. The first was defined as the weighted average operating speed of the previous road section based on distance, and represents drivers’ expectancies, whereas the second represents road behavior. However, drivers’ expectancies are related to short-term memory which declines gradually and depends on time. Thus, a time-based inertial operating speed would allow a more accurate estimation of the phenomenon. This research analyzes different periods of time and weighting distributions to identify how drivers’ expectancies should be estimated. A set of 71 homogeneous road segments located in Italy were considered in the study. As a result, 25 seconds and a convex parabolic distribution should be used to calculate the inertial operating speed profile. This new way of estimating drivers’ expectancies showed better results than those obtained based on distance. Finally, the proposed consistency model was compared with the previous models and was found to be able to assess more accurately the geometric design consistency. Therefore, the proposed consistency model is a useful tool for engineers to estimate the number of crashes so that they can incorporate road safety considerations into the geometric design of either new two-lane rural roads, or improving the existing ones.

scholarly journals New geometric design consistency model based on operating speed profiles for road safety evaluation

2013 ◽  
Vol 61 ◽  
pp. 33-42 ◽  
Author(s):  
Francisco J. Camacho-Torregrosa ◽  
Ana M. Pérez-Zuriaga ◽  
J. Manuel Campoy-Ungría ◽  
Alfredo García-García
Keyword(s):  
Road Safety ◽  
Safety Evaluation ◽  
Geometric Design ◽  
Operating Speed ◽  
Model Based ◽  
Consistency Model ◽  
Design Consistency

Evaluating Horizontal Alignment Design Consistency of Two-Lane Rural Highways: Development of New Procedure

2000 ◽  
Vol 1737 (1) ◽  
pp. 9-17 ◽  
Author(s):  
John McFadden ◽  
Lily Elefteriadou
Keyword(s):  
Primary Objective ◽  
Maximum Speed ◽  
Operating Speed ◽  
Speed Profile ◽  
Horizontal Curve ◽  
Rural Highways ◽  
Speed Reduction ◽  
Design Elements ◽  
The Difference ◽  
Design Consistency

Design consistency refers to the condition wherein the roadway geometry does not violate driver expectations. Operating-speed profile models are used to evaluate the consistency of a design by identifying locations with large speed variability between successive design elements. There is a direct correlation between safety and variability in speeds. Recent operating-speed models predict the 85th percentile speeds on horizontal curves and compare this value with the expected 85th percentile speed on the approach tangent. There is a direct correlation between speed variability between successive design elements and crash rates. Eighty-fifth percentile speeds, however, do not necessarily represent the speed reductions experienced by drivers. The primary objective of the research was to assess the efficacy of the use of 85th percentile speed by operating-speed profile models to evaluate the consistency of a design. Speed data were collected at 21 horizontal curve sites. These data were used to evaluate the implication of using 85th percentile speed for evaluating design consistency. A new parameter was investigated for analyzing design consistency: the 85th percentile maximum reduction in speed (85MSR). This parameter is calculated by using each driver’s speed profile from an approach tangent through a horizontal curve and determining the maximum speed reduction each driver experiences. These maximum speed reductions are sorted, and the 85th percentile value becomes the statistic of interest, or 85MSR. 85MSR was compared with the difference in 85th percentile speeds (85S), and it was found that 85MSR is significantly larger than 85S. The data showed that, on average, 85MSR is approximately two times larger than 85S. Models were developed that predict 85MSR as a function of geometric design elements, and these models could be used to complement existing operating-speed models.

scholarly journals OPERATING SPEED AS A KEY FACTOR IN STUDYING THE DRIVER BEHAVIOUR IN A RURAL CONTEXT

Transport ◽  
2016 ◽  
Vol 31 (2) ◽  
pp. 260-270 ◽  
Author(s):  
Francesca Russo ◽  
Salvatore Antonio Biancardo ◽  
Mariarosaria Busiello
Keyword(s):  
Prediction Models ◽  
Weather Conditions ◽  
Ordinary Least Squares ◽  
Segment Length ◽  
Operating Speed ◽  
Driver Behaviour ◽  
Statistical Parameters ◽  
Explanatory Variables ◽  
Circular Curves ◽  
Road Segments

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.

scholarly journals Accident Prediction based on Integrated Design Consistency with the Lower Number of Vehicles/Traffic Volumes (due to Health Disaster/COVID-19)

2020 ◽  
Vol 3 (3) ◽  
pp. 287-295
Author(s):  
Joewono Prasetijo ◽  
Guohui Zhang ◽  
Muhammad Isradi ◽  
Zaffan Farhana Zainal ◽  
Wan Zahidah Musa ◽  
...  
Keyword(s):  
Integrated Design ◽  
Access Point ◽  
Road Accident ◽  
Speed Profile ◽  
Passenger Cars ◽  
Road Design ◽  
Consistency Model ◽  
Traffic Volumes ◽  
Design Consistency ◽  
The Impact

Purpose: Malaysia is one of the developing countries that facing high road accident in Asia. The most common accident happens is between motorcyclist and cars. A motorcyclist is 17 times more dangerous than passenger cars. Analysis shows the three main types of accidents in Malaysia is collision with passenger cars, collisions with other motorcycles and single-motorcycle accidents. Road accidents keep rising in Malaysia, because lacks of road geometric design consistency where the drivers make mistakes errors due to the road geometric features. Design/methodology/approach: The study was conducted at F0050 from km 21 until km 25. By using GPS (DG -200), the continuous speed profile data were using new analysis method to develop road design consistency profile of motorcycle and cars and determined the value of the index the integrated road design consistency (IC). Findings: The developments of consistency model are based on parameter: the bounded area between the profile and the average speed, standard deviation of speed along a segment. Hence, use ACAD software for develops consistency model’s profile. The integrated-consistency model is the impact of the speed profile on design consistency in traffic and safety evaluations. The highest areas of an accident at km 24 are justified based on the design consistency of the area and integrated design consistency model between of car and motorcycle is poor design. The study shows that crashes and fatalities are fully effected by traffic volumes but road design performances and driving behavior. Research limitations/implications: However, the traffic volumes are relatively low in the whole country regarding to the Movement Control Order (MCO) due to the pandemic COVID-19 since March 2020. In contrast to the reduction of the volumes, the number of crashes still shows relatively high. Therefore, it shows that crashes and fatalities are influenced by other factors. Geometric factors such as access point, tangent length, curve length, shoulder width, and lane width are influencing an operating speed profile for developed tangents and curves of motorcycle and cars. Practical implications: The result of this study can be used as references to solve accident problems in Malaysia. Paper type: This study is categorized as a case study.

Weatherwise: Evaluation of a Cue-Based Training Approach for the Recognition of Deteriorating Weather Conditions during Flight

2003 ◽  
Vol 45 (2) ◽  
pp. 337-345 ◽  
Author(s):  
Mark Wiggins ◽  
David O'Hare
Keyword(s):  
Decision Making ◽  
Significant Proportion ◽  
Evaluation Process ◽  
Weather Conditions ◽  
The United States ◽  
Training System ◽  
General Aviation ◽  
Self Report ◽  
Computer Based Training ◽  
Computer Based

Inappropriate and ineffective weather-related decision making continues to account for a significant proportion of general aviation fatalities in the United States and elsewhere. This study details the evaluation of a computer-based training system that was developed to provide visual pilots with the skills necessary to recognize and respond to the cues associated with deteriorating weather conditions during flight. A total of 66 pilots were assigned to one of two groups, and the evaluation process was undertaken at both a self-report and performance level. At the self-report level, the results suggested that pilots were more likely to use the cues following exposure to the training program. From a performance perspective, there is evidence to suggest that cue-based training can improve the timeliness of weather-related decision making during visual flight rules flight. Actual or potential applications of this research include the development of computer-based training systems for fault diagnosis in complex industrial environments.

Studying Driving Behavior on Horizontal Curves using Naturalistic Driving Study Data

2018 ◽  
Vol 2672 (17) ◽  
pp. 83-95 ◽  
Author(s):  
Bashar Dhahir ◽  
Yasser Hassan
Keyword(s):  
Data Collection ◽  
Weather Conditions ◽  
Driving Behavior ◽  
Study Data ◽  
Output Analysis ◽  
Horizontal Curves ◽  
Naturalistic Driving Study ◽  
Naturalistic Driving ◽  
Design Consistency ◽  
Favorable Weather

Many studies have been conducted to develop models to predict speed and driver comfort thresholds on horizontal curves, and to evaluate design consistency. The approaches used to develop these models differ from one another in data collection, data processing, assumptions, and analysis. However, some issues might be associated with the data collection that can affect the reliability of collected data and developed models. In addition, analysis of speed behavior on the assumption that vehicles traverse horizontal curves at a constant speed is far from actual driving behavior. Using the Naturalistic Driving Study (NDS) database can help overcome problems associated with data collection. This paper aimed at using NDS data to investigate driving behavior on horizontal curves in terms of speed, longitudinal acceleration, and comfort threshold. The NDS data were valuable in providing clear insight on drivers’ behavior during daytime and favorable weather conditions. A methodology was developed to evaluate driver behavior and was coded in Matlab. Sensitivity analysis was performed to recommend values for the parameters that can affect the output. Analysis of the drivers’ speed behavior and comfort threshold highlighted several issues that describe how drivers traverse horizontal curves that need to be considered in horizontal curve design and consistency evaluation.

Formulation and Validation of Operating Speed-Based Design Consistency Models by Bootstrapping

1997 ◽  
Vol 1579 (1) ◽  
pp. 97-103 ◽  
Author(s):  
John McFadden ◽  
Lily Elefteriadou
Keyword(s):  
Additional Data ◽  
Original Data ◽  
Statistical Technique ◽  
Geometric Design ◽  
Operating Speed ◽  
Horizontal Alignment ◽  
Alternative Means ◽  
Design Speed ◽  
Design Consistency ◽  
Consistency Models

Current U.S. policy for designing rural two-lane highways is based on design speed to ensure consistency among consecutive highway segments. The design speed concept, however, does not ensure that a consistent alignment will be achieved. A recent FHWA-sponsored project (Horizontal Alignment Design Consistency for Rural Two-Lane Highways) led to three operating speed-based geometric design consistency models, which have not yet been validated. Traditionally, the validation of such models involves the collection of additional data. The statistical technique known as “bootstrapping” was used to formulate and validate the operating speed-based geometric design consistency models by using the existing FHWA database. Bootstrapping involves random sampling with replacement from the existing database, which becomes the population. One-half of the original data collected are used in formulating the models. The remaining half of the data are subsequently used for validation. The models resulting from bootstrapping were statistically equivalent to the models developed in the FHWA study. In addition, the model validation indicated that the bootstrapping technique used to validate the operating speed models is a viable alternative means of validation. It was concluded that bootstrapping is a very useful tool that can be exploited in many related areas in the transportation field, especially because of the large amounts of data typically required in developing and validating empirical models.

Speed-Profile Model for Two-Lane Rural Highways

2000 ◽  
Vol 1737 (1) ◽  
pp. 42-49 ◽  
Author(s):  
Kay Fitzpatrick ◽  
Jon M. Collins
Keyword(s):  
Highway Safety ◽  
Geometric Features ◽  
Speed Profile ◽  
Model Design ◽  
Rural Highways ◽  
Profile Model ◽  
Safety Design ◽  
Acceleration And Deceleration ◽  
Speed Prediction ◽  
Design Consistency

Design consistency refers to highway geometry’s conformance with driver expectancy. Generally, drivers make fewer errors at geometric features that conform with their expectations. A proposed method for evaluating design consistency is to predict the speed along an alignment by using a speed-profile model. A speed-profile model was developed by using the following: speed prediction equations that calculate the expected speed at horizontal, vertical, or combination curves; assumed desired speed for the roadway; TWOPAS equations that determine the performance-limited speeds at every point; acceleration and deceleration rates; and several documented assumptions. The speed-profile model can be used to evaluate the design consistency of a facility or to generate a speed profile along an alignment. In conclusion, the speed-profile model developed appears to provide a suitable basis for the Interactive Highway Safety Design Model design consistency module.

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