Continuous Speed Profiles to Investigate Drivers' Behavior on Two-Lane Rural Highways

2015 ◽  
Vol 2521 (1) ◽  
pp. 3-11 ◽  
Author(s):  
Alfonso Montella ◽  
Francesco Galante ◽  
Filomena Mauriello ◽  
Massimo Aria
Keyword(s):  
Driving Simulator ◽  
Prediction Models ◽  
Piecewise Linear ◽  
Small Radius ◽  
Operating Speed ◽  
Data Set ◽  
Highway Design ◽  
Rural Highways ◽  
Acceleration And Deceleration ◽  
Design Consistency

To improve highway design consistency, several studies developed operating speed prediction models and investigated drivers' speed behavior. Most existing models are based on spot speed data that assume constant operating speed throughout the horizontal curves and occurrence of acceleration and deceleration only on tangents. To overcome limitations associated with existing models, this study investigated continuous speed profiles with an experiment that used a high-fidelity dynamic-driving simulator on a two-lane highway. A piecewise linear regression model and locally weighted regression scatter-plot smoothing were used to remove noise in the data set while preserving underlying patterns and to identify significant changes in the speed profile. Based on the smoothed speed profiles, models to predict operating speed in curves and in tangents, deceleration and acceleration rates to be used in the operating speed profiles, and starting and ending points of constant operating speed in curve were developed. Radius of the curve notably affected not only the operating speed in the curve but also the operating speed of the tangent following the curve: the smaller the radius, the lower the operating speed of the exit tangent. Both acceleration and deceleration rates increased with curvature. This study found that operating speed was not constant along curves. On small radius curves, deceleration ended close to the center of the curve, and acceleration starts, close to the end of the curve. Increasing the curve radius, the end point of deceleration moves toward the curve's beginning, whereas the start of acceleration moves toward the center of the curve.

Establishing highway horizontal alignment to maximize design consistency

2007 ◽  
Vol 34 (9) ◽  
pp. 1159-1168 ◽  
Author(s):  
Said M Easa ◽  
Atif Mehmood
Keyword(s):  
Geometric Features ◽  
Trial And Error ◽  
Highway Design ◽  
Rural Highways ◽  
Physical Constraints ◽  
Horizontal Alignment ◽  
Horizontal Curves ◽  
Decision Variables ◽  
Acceleration And Deceleration ◽  
Design Consistency

Highway design consistency is one of the important criteria in selecting the geometric features of proposed or existing alignments of two-lane rural highways. Operating-speed (OS) profile models have been used to evaluate design consistency by trial and error. For a proposed new highway, however, there may be geometric and physical constraints, and selection of these elements by trial and error to achieve optimal design consistency would be difficult, if not impossible. This paper presents an optimization model that establishes highway horizontal alignment to achieve maximum design consistency based on the OS profile. The decision variables of the model include radius of horizontal curves, spiral curve lengths, length of speed-change (SC) segments, and acceleration and deceleration rates. The objective function of the model minimizes the mean OS difference or the maximum OS difference for successive geometric features along the highway section. Application examples and sensitivity analysis are presented to illustrate the capabilities of the model in evaluating improvement strategies and to ensure that the model produces sound optimum alignments. The proposed model, which complements existing optimization models that mainly address highway construction cost, should be of interest to highway practitioners and engineers.Key words: design consistency, highway, geometric, horizontal alignment, optimization modeling, speed profile.

Effect of geometric design consistency on road safety

2004 ◽  
Vol 31 (2) ◽  
pp. 218-227 ◽  
Author(s):  
Joanne C.W Ng ◽  
Tarek Sayed
Keyword(s):  
Road Safety ◽  
Prediction Models ◽  
Model Development ◽  
Geometric Design ◽  
Highway Design ◽  
Rural Highways ◽  
Accident Prediction ◽  
Design Characteristics ◽  
Design Consistency ◽  
The Impact

Geometric design consistency is emerging as an important rule in highway design. Identifying and treating any inconsistency on a highway can significantly improve its safety performance. Considerable research has been undertaken to explore this concept including identifying potential consistency measures and developing models to estimate them. However, little work has been carried out to quantify the safety benefits of geometric design consistency. The objectives of this study are to investigate and quantify the relationship between design consistency and road safety. A comprehensive accident and geometric design database of two-lane rural highways is used to investigate the effect of several design consistency measures on road safety. Several accident prediction models that incorporate design consistency measures are developed. The generalized linear regression approach is used for model development. The models can be used as a quantitative tool for the evaluation of the impact of design consistency on road safety. An application is presented where the ability of accident prediction models that incorporate design consistency measures is compared with those that rely on geometric design characteristics. It is found that models that explicitly consider design consistency may identify the inconsistencies more effectively and reflect the resulting impacts on safety more accurately than those that do not.Key words: geometric design consistency, road safety, quantification, accident prediction models.

scholarly journals Evaluation of Driver Visual Demand on Three-Dimensional Rural Highway Alignments

2021 ◽  
Author(s):  
Wen Long He
Keyword(s):  
Driving Simulator ◽  
3D Visualization ◽  
Three Dimensional ◽  
Highway Design ◽  
K Value ◽  
Rural Highways ◽  
State Highway ◽  
Demand Models ◽  
Driver Workload ◽  
Design Consistency

This research focuses on evaluating driver visual demand on three-dimensional (3D) highway alignments consisting of combined horizontal and vertical alignments which is an important part of highway design consistency research. Using a driving simulator, ten hypothetical 2D and 3D alignments for two-lane rural highways were developed, following the standard guidelines of the Transportation Association of Canada (TAC) and the American Association of State Highway Transportation Officials (AASHTO). Fifteen driver subjects drove in the simulator. The data relating to visual demand information were processed and analysed using Microsoft Excel and SAS statistical software. The results indicated that visual demand on 3D curves varies widely with the inverse of radius of horizontal curvature and the inverse of K value of vertical curvature. Age played another important role on visual demand. Models for evaluating visual demand on 3D highway alignments were developed for curves and tangents. The models developed in this study have been applied to horizontal and 3D alignments to carry out a design consistency evaluation. In addition, GIS virtual reality technique was applied to present the visual demand results for a real highway on the 3D visualization model. 3D visualization not only offers a better understanding of driver workload along the highway, but also represents an important tool to effectively manage information.

scholarly journals Evaluation of Driver Visual Demand on Three-Dimensional Rural Highway Alignments

2021 ◽  
Author(s):  
Wen Long He
Keyword(s):  
Driving Simulator ◽  
3D Visualization ◽  
Three Dimensional ◽  
Highway Design ◽  
K Value ◽  
Rural Highways ◽  
State Highway ◽  
Demand Models ◽  
Driver Workload ◽  
Design Consistency

This research focuses on evaluating driver visual demand on three-dimensional (3D) highway alignments consisting of combined horizontal and vertical alignments which is an important part of highway design consistency research. Using a driving simulator, ten hypothetical 2D and 3D alignments for two-lane rural highways were developed, following the standard guidelines of the Transportation Association of Canada (TAC) and the American Association of State Highway Transportation Officials (AASHTO). Fifteen driver subjects drove in the simulator. The data relating to visual demand information were processed and analysed using Microsoft Excel and SAS statistical software. The results indicated that visual demand on 3D curves varies widely with the inverse of radius of horizontal curvature and the inverse of K value of vertical curvature. Age played another important role on visual demand. Models for evaluating visual demand on 3D highway alignments were developed for curves and tangents. The models developed in this study have been applied to horizontal and 3D alignments to carry out a design consistency evaluation. In addition, GIS virtual reality technique was applied to present the visual demand results for a real highway on the 3D visualization model. 3D visualization not only offers a better understanding of driver workload along the highway, but also represents an important tool to effectively manage information.

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.

scholarly journals Evaluation of driver visual demand at different traffic volumes on complex two-dimensional multi-lane highway alignments.

2021 ◽  
Author(s):  
Lisa Kadoury
Keyword(s):  
Driving Simulator ◽  
Two Dimensional ◽  
Highway Design ◽  
Geometric Characteristics ◽  
The Road ◽  
Complex Curves ◽  
Traffic Volumes ◽  
Process Output ◽  
Design Consistency ◽  
Crucial Part

This research focuses on evaluating driver visual demand at different traffic volumes along with geometric design features for two-dimensional (2D) multi-lane highways consisting of horizontal and vertical alignments which is a crucial part of highway design consistency research. Three such alignments, with simple and complex curves were designed to generate desired traffic volume levels. A driving simulator was used to collect date from twenty drivers that participated in roadway alignment experiments at Ryerson University. Statistical Analysis Software (SAS) was used to analyze and process output data. Models were developed for visual demand and volume/capacity ratios, and geometric characteristics of the road, where visual demand was the only dependent variable. The research found that a relationship exists between visual demand and different traffic volumes along with geometric characteristics of the road.

scholarly journals Evaluation of driver visual demand at different traffic volumes on complex two-dimensional multi-lane highway alignments.

2021 ◽  
Author(s):  
Lisa Kadoury
Keyword(s):  
Driving Simulator ◽  
Two Dimensional ◽  
Highway Design ◽  
Geometric Characteristics ◽  
The Road ◽  
Complex Curves ◽  
Traffic Volumes ◽  
Process Output ◽  
Design Consistency ◽  
Crucial Part

This research focuses on evaluating driver visual demand at different traffic volumes along with geometric design features for two-dimensional (2D) multi-lane highways consisting of horizontal and vertical alignments which is a crucial part of highway design consistency research. Three such alignments, with simple and complex curves were designed to generate desired traffic volume levels. A driving simulator was used to collect date from twenty drivers that participated in roadway alignment experiments at Ryerson University. Statistical Analysis Software (SAS) was used to analyze and process output data. Models were developed for visual demand and volume/capacity ratios, and geometric characteristics of the road, where visual demand was the only dependent variable. The research found that a relationship exists between visual demand and different traffic volumes along with geometric characteristics of the road.

scholarly journals Empirical Speed Behavior on Horizontal Ramp Curves in Interchanges in the Netherlands

2017 ◽  
Vol 2618 (1) ◽  
pp. 38-47 ◽  
Author(s):  
Haneen Farah ◽  
Aries van Beinum ◽  
Winnie Daamen
Keyword(s):  
The Netherlands ◽  
Prediction Models ◽  
Operating Speed ◽  
Trajectory Data ◽  
Design Elements ◽  
The Road ◽  
Road Design ◽  
Speed Prediction ◽  
Design Consistency ◽  
High Level

Several studies in the literature have indicated that interchanges are the most crash-prone areas within the motorway system in number and severity of accidents. The reason is the high level of turbulence as a result of vehicle lane changes and speed variability. To understand the safety consequences of an interchange design (e.g., type of connecting ramps, radii and superelevation of curves, and lane and shoulder widths), an in-depth investigation of driving speed behavior is needed. Such an investigation requires the collection of detailed trajectory data on vehicles on different interchanges. These types of data are rarely available, and as a result, such studies are scarce in the literature. The main objective of this present study was to analyze driver speed behavior on different ramps at interchanges, and to develop an operating speed prediction model as a function of the road design elements. Trajectory data on free-moving vehicles were derived from stabilized video images taken from a camera mounted underneath a helicopter, which hovered over the road areas studied. Data were collected from 29 curves at six freeway–freeway interchanges in the Netherlands. The sample included nine direct connections, 12 semidirect connections, and eight indirect connections. The findings showed that speeds were affected by several road geometric characteristics of the curves, by driver expectancy and design consistency, and by the percentage of trucks in traffic. The operating speed prediction models developed in the study will provide designers with tools to estimate the operating speed during the design process.

Impact of highway consistency on capacity utilization of two-lane rural highways

1999 ◽  
Vol 26 (6) ◽  
pp. 789-798 ◽  
Author(s):  
Gamal M Gibreel ◽  
Ibrahim A El-Dimeery ◽  
Yasser Hassan ◽  
Said M Easa
Keyword(s):  
Traffic Safety ◽  
Research Work ◽  
Three Dimensional ◽  
Capacity Utilization ◽  
3D Analysis ◽  
Horizontal Curve ◽  
Highway Capacity ◽  
Highway Design ◽  
Rural Highways ◽  
Design Consistency

Consistent highway design is expected to provide safe, economical, and smooth traffic operation. Several studies have been performed to investigate the effect of highway consistency on traffic safety. However, the relationship between design consistency and highway capacity and level of service has not been addressed in current research work and design practices. In addition, the effect of the three-dimensional (3D) nature of highway alignments was not considered, and design consistency was studied based solely on two-dimensional (2D) analysis of highway horizontal alignments. This paper presents a methodology to determine the effect of highway design consistency on highway capacity utilization based on 3D analysis. This methodology will help road designers to estimate highway capacity more accurately. The study was performed on two-lane rural highways in Ontario, where two types of 3D combinations were considered: a horizontal curve combined with a sag vertical curve (sag combination) and a horizontal curve combined with a crest vertical curve (crest combination). An additional adjustment factor that reflects the effect of highway design consistency on capacity utilization was developed. Different statistical models are introduced to estimate this factor based on geometric or traffic data. In addition, typical values of the consistency factor were developed based on an overall consistency evaluation criterion and can be easily used in capacity analysis.Key words: three-dimensional, alignments, capacity, geometric design, operating speed, 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.

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