Sustainable design of rural roads with 2+1 road design: Levels of service and traffic flow performance

2016 ◽  
Vol 20 (3) ◽  
pp. 1032-1039 ◽  
Author(s):  
Jaisung Choi ◽  
Youngrok Kim ◽  
Torsten Bergh ◽  
Sangyoup Kim ◽  
Sungkyu Kim
Keyword(s):  
Traffic Flow ◽  
Sustainable Design ◽  
Rural Roads ◽  
Road Design ◽  
Levels Of Service

scholarly journals A Crash Surrogate Metric considering Traffic Flow Dynamics in a Motorway Corridor

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Xu Wang ◽  
Kai Liu
Keyword(s):  
Traffic Flow ◽  
Risk Index ◽  
Simple Calculation ◽  
Flow Dynamics ◽  
Crash Data ◽  
Time To Collision ◽  
Crash Rates ◽  
Crash Surrogate ◽  
Surrogate Measures ◽  
Levels Of Service

We proposed a new crash surrogate metric, i.e., the maximum disturbance that a car following scenario can accommodate, to represent potential crash risks with a simple closed form. The metric is developed in consideration of traffic flow dynamics. Then, we compared its performance in predicting the rear-end crash risks for motorway on-ramps with other two surrogate measures (time to collision and aggregated crash index). To this end, a one-lane on-ramp of Pacific Motorway, Australia, was selected for this case study. Due to the lack of crash data on the study site, historical crash counts were merged according to levels of service (LOS) and then converted into crash rates. In this study, we used the societal risk index to represent the crash surrogate indicators and built relationships with crash rates. The final results show that (1) the proposed metric and aggregated crash index are superior to the time to collision in predicting the rear-end crash risks for on-ramps; (2) they have a relatively similar performance, but due to the simple calculation, the proposed metric is more applicable to some real-world cases compared with the aggregated crash index.

Study of Setting of Bus Bay Stop Based on VISSIM

2014 ◽  
Vol 641-642 ◽  
pp. 906-909
Author(s):  
Jian Jun Wang ◽  
Xin Ting Huang ◽  
Ning Zhao
Keyword(s):  
Traffic Flow ◽  
Delay Time ◽  
Road Traffic ◽  
Microscopic Simulation ◽  
Total Delay ◽  
Urban Road ◽  
Bus Stop ◽  
Road Design ◽  
Bus Station ◽  
Road System

Setting state of bus stop affects the efficiency of the entire road system. Through discussing bus bay stop’s width, length and distance to intersection, a microscopic simulation was conducted in this paper. With a certain bus frequency, the total delay time of vehicles was analyzed under different road traffic in different forms of Da Yanta Bus Station in Xi’an. The results show that setting bus bay stops on the secondary roads which have large traffic flow can significantly reduce delay time, and can provide references for urban road design.

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.

Highway Alignment Optimization Using Cost-Benefit Analysis Under User Equilibrium

2013 ◽  
pp. 313-327 ◽  
Author(s):  
Avijit Maji ◽  
Manoj K. Jha
Keyword(s):  
Traffic Flow ◽  
Road Network ◽  
Cost Benefit Analysis ◽  
Cost Benefit ◽  
User Equilibrium ◽  
User Cost ◽  
Benefit Analysis ◽  
Road Design ◽  
Highway Alignment Optimization ◽  
Highway Alignment

Usually, selection of a highway alignment depends on an economical route that minimizes alignment sensitive costs, such as construction cost, user cost, right-of-way cost, and earthwork cost. Most of the available highway alignment optimization algorithms do not consider traffic assignment and distribution of traffic as a result of the new road network consisting of the new alignment as well as other pre-existing alignments. Constructing a new highway will ease the traffic in the existing road network. Based on Wardrop’s principle, the users will choose a route that will minimize their travel-time. Users will unilaterally shift to the available routes for their benefit and thus, traffic flow will attain equilibrium. Theoretically, the equilibrium of traffic flow between the existing highway and the newly designed highway alternative can be achieved by a user equilibrium model. A new methodology is developed in this paper to optimize a new three-dimensional highway alignment based on the existing highway alignment system information using a cost-benefit analysis approach. The results are quite promising for new road design and bypass construction since benefit maximization and cost minimization is performed simultaneously while attaining user equilibrium.

Road proximity and traffic flow perceived as potential predation risks: evidence from the Tibetan antelope in the Kekexili National Nature Reserve, China

2011 ◽  
Vol 38 (2) ◽  
pp. 141 ◽  
Author(s):  
Xinming Lian ◽  
Tongzuo Zhang ◽  
Yifan Cao ◽  
Jianping Su ◽  
Simon Thirgood
Keyword(s):  
Traffic Flow ◽  
Human Disturbance ◽  
Avoidance Behaviour ◽  
Risk Avoidance ◽  
Time Frequency ◽  
The Road ◽  
Road Design ◽  
Focal Animal ◽  
Tibetan Antelope ◽  
Disturbance Hypothesis

Context The risk-disturbance hypothesis predicts that animals exhibit risk-avoidance behaviours when exposed to human disturbance because they perceive the disturbance as a predatory threat. Aims This study aimed to examine whether Tibetan antelopes (Pantholops hodgsoni) exhibit risk-avoidance behaviour with proximity to a major highway and with increasing traffic flow consistent with the risk-disturbance hypothesis. Methods Focal-animal sampling was used to observe the behaviour of Tibetan antelopes. The behaviours were categorised as foraging, vigilance, resting, moving, or other. The time, frequency, and duration of foraging and vigilance were calculated. Key results As distance from the road increased, time spent foraging and foraging duration increased while foraging frequency, time spent being vigilant and vigilance frequency decreased, indicating that there is a risk perception associated with roads. Tibetan antelopes presented more risk-avoidance behaviours during high-traffic periods compared with low-traffic periods. Conclusions Tibetan antelopes exhibited risk-avoidance behaviour towards roads that varied with proximity and traffic levels, which is consistent with the risk-disturbance hypothesis. Implications The consequences of risk-avoidance behaviour should be reflected in wildlife management by considering human disturbance and road design.

scholarly journals Exploring Traffic Congestion on Urban Expressways Considering Drivers' Unreasonable Behavior at Merge/Diverge Sections

2018 ◽  
Author(s):  
Kejun Long ◽  
Qin Lin ◽  
Jian Gu ◽  
Wei Wu
Keyword(s):  
Traffic Flow ◽  
Traffic Congestion ◽  
Queue Length ◽  
Transmission Model ◽  
Cell Transmission Model ◽  
Spatiotemporal Evolution ◽  
Lane Changing ◽  
Road Design ◽  
Urban Expressway ◽  
Road Geometry

Mechanism of traffic congestion generation is more than complicated, due to complex geometric road design and complicated driving behavior at urban expressway in China. We employ Cell transmission model (CTM) to simulate traffic flow spatiotemporal evolution process along the expressway, and reveal the characteristics of traffic congestion occurrence and propagation. Here we apply the variable-length-cell CTM to adapt the complicated road geometry and configuration, and propose the merge section CTM considering drivers' mandatory lane-changing and other unreasonable behavior at on-ramp merge section, and propose the diverge section CTM considering queue length end extending expressway mainline to generate dynamic bottleneck at diverge section. In the new improved CTM model, we introduce merge ratio and diverge ratio to describe the effect of driver behavior at merge and diverge section. We conduct simulation on the real urban expressway in China, results show that merge section and diverge section are the original location of expressway traffic congestion generation, on/off-ramp traffic flow has great effect on expressway mainline operation. When on-ramp traffic volume increases by 40%, merge section delay increases by 35%. And when off-ramp capacity increases by 100 veh/hr, diverge section delay decreases about by 10%, which proves the strong interaction between expressway and adjacent road networks . Our results provide the underlying insights of traffic congestion mechanism in urban expressway in China, which can be used to better understand and manage this issue.

scholarly journals Detection of Geometric Risk Factors Affecting Head-On Collisions through Multiple Logistic Regression: Improving Two-Way Rural Road Design via 21 Road Adaptation+

2021 ◽  
Vol 18 (12) ◽  
pp. 6598
Author(s):  
Laura Cáceres ◽  
Miguel A. Fernández ◽  
Alfonso Gordaliza ◽  
Aquilino Molinero
Keyword(s):  
Risk Factors ◽  
Logistic Regression ◽  
Protective Factor ◽  
Ad Hoc ◽  
Design Parameters ◽  
Multiple Logistic Regression ◽  
Rural Roads ◽  
Factors Affecting ◽  
Logistic Regression Models ◽  
Road Design

This study aims to characterize locations on two-way rural roads where head-on crashes are more likely to occur, attending to geometric road design factors. For this purpose, a case-control study was carried out using multiple logistic regression models with variables related to road design parameters, considering several scenarios. The dataset corresponding to cases (places where crashes have occurred) was collected on Spanish “1+1” rural roads over a four-year period. The controls (places where no crashes have occurred in the period) where randomly selected through a specific ad hoc designed method. The obtained model identifies risk factors and allows the computation of the odds of a head-on collision on any specific road section: width of the pavement (when it exceeds 6 m), width of the lanes (for intermediate widths between 3.25 and 3.75 m) and tight curves (less than 250 m of radius) are identified as factors significantly increasing the odds of a crash, whereas a paved shoulder is a protective factor. The identified configurations on two-way rural roads may be susceptible to transformation into “2+1” roads to decrease the odds of a head-on crash, thus preventing possible serious injuries and enhancing transportation safety.

Driving Dynamic Aspects and Related Safety Issues for Modern Geometric Design of Non-Built-Up Roads

1996 ◽  
Vol 1523 (1) ◽  
pp. 34-45
Author(s):  
Ruediger Lamm ◽  
Basil Psarianos ◽  
George Soilemezoglou ◽  
George Kanellaidis
Keyword(s):  
Geometric Design ◽  
Driving Dynamic ◽  
Safety Criterion ◽  
Rural Roads ◽  
Safety Issues ◽  
Road Design ◽  
Friction Factors ◽  
The Status ◽  
Design Consistency ◽  
Side Friction

Safety issues affecting modern highway geometric design of roads in non-built-up areas are discussed. The status of knowledge of Safety Criteria I and II (achieving operating speed consistency and design consistency) for two-lane rural roads is briefly reviewed. Considerations for design consistency are also extended to multiple-lane rural and suburban road design to evaluate good, fair, and poor design levels for these road categories. Utilization ratios (n) for maximum permissible side friction factors are developed for different road categories, topography levels, and maximum and minimum superelevation rates. Relevant minimum radii for curve design are established and compared with present AASHTO values insofar as possible. Safety Criterion III (achieving driving dynamic consistency) is further developed, through which reliable and quantitative ranges between the side friction assumed and the actual friction demand at curved sites could be established. AASHTO's design policy is evaluated on the basis of Criteria II and III. The evaluation showed, for lower design speeds (30, 40, and 50 mph), an unbalanced degree of curve and superelevation rate ranges, which lead to poor design practices from a safety viewpoint. By heeding the three safety criteria and the recommended side-friction utilization ratios, sound alignments can be established for the various design cases in future highway geometric design and redesign and for resurfacing, restoration, and rehabilitation strategies.

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