scholarly journals Sight distances at unsignalized intersections: a comparison of guidelines and requirements for human drivers and autonomous vehicles

2021 ◽  
Vol 59 (3) ◽  
pp. 7-19
Author(s):  
Zsófia Magyari ◽  
Csaba Koren ◽  
Mariusz Kieć ◽  
Attila Borsos
Keyword(s):  
Autonomous Vehicles ◽  
Traffic Accidents ◽  
Human Vision ◽  
Design Parameters ◽  
Major Road ◽  
Gap Acceptance ◽  
Human Capabilities ◽  
Road Design ◽  
Unsignalized Intersections ◽  
Minor Road

Many traffic accidents are caused by unforeseen and unexpected events in a site that was hidden from the driver's eyes. Road design parameters determining required visibility are based on relationships formulated decades ago. It is worth reviewing them from time to time in the light of technological developments. In this paper, sight distances for stopping and crossing situations are studied in relation to the assumed visual abilities of autonomous vehicles. Current sight distance requirements at unsignalized intersections are based among others on speeds on the major road and on ac-cepted gaps by human drivers entering or crossing from the minor road. Since these requirements vary from country to country, regulations and sight terms of a few selected countries are compared in this study. From the comparison it is remarkable that although the two concepts, i.e. gap acceptance on the minor road and stopping on the major road have different backgrounds, but their outcome in terms of required sight distances are similar. Both distances are depending on speed on the major road: gap sight distances show a linear, while stopping sight distances a parabolic function. In general, European SSD values are quite similar to each other. However, the US and Australian guidelines based on gap acceptance criteria recommend higher sight distances. Human capabilities and limitations are considered in sight field requirements. Autonomous vehicles survey their environment with sensors which are different from the human vision in terms of identifying objects, estimating distances or speeds of other vehicles. This paper compares current sight field requirements based on conventional vehicles and those required for autonomous vehicles. Visibility requirements were defined by three vision indicators: distance, angle of view and resolution abilities of autonomous cars and human drivers. These indicators were calculated separately for autonomous vehicles and human drivers for various speeds on the main road and for intersections with 90° and 60° angles. It was shown that the required sight distances are 10 to 40 meters shorter for autonomous vehicles than for conventional ones.

Sight Distance for Stop-Controlled Intersections Based on Gap Acceptance

2000 ◽  
Vol 1701 (1) ◽  
pp. 32-41 ◽  
Author(s):  
Douglas W. Harwood ◽  
John M. Mason ◽  
Robert E. Brydia
Keyword(s):  
Travel Time ◽  
Field Studies ◽  
Major Road ◽  
Gap Acceptance ◽  
Road Vehicle ◽  
Sight Distance ◽  
Minor Road ◽  
Distance Model ◽  
Design Speed ◽  
A Minor

The current AASHTO policy for sight distance at Stop-controlled intersections is based on a model of the acceleration performance of a minor-road vehicle turning left or right onto a major road and the deceleration performance of the following major road vehicle. An alternative intersection sight distance model based on gap acceptance is developed and quantified. Field studies that were performed to determine the critical gaps appropriate for use in sight distance design are described. It is recommended that the sight distance along the major road for a passenger car at a Stop-controlled intersection should be based on a distance equal to 7.5 s of travel time at the design speed of the major road. Longer sight distances are recommended for minor-road approaches that have sufficient truck volumes to warrant consideration of a truck as the design vehicle.

scholarly journals Exploring Factors Impacting Paths of Left-Turning Vehicles from Minor Road Approach at Unsignalized Intersections

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Guoqiang Zhang ◽  
Yuli Qi ◽  
Jun Chen
Keyword(s):  
Traffic Safety ◽  
Major Road ◽  
Traffic Crashes ◽  
Factors Affecting ◽  
Traffic Efficiency ◽  
Logistic Analysis ◽  
Unsignalized Intersections ◽  
Minor Road ◽  
Traffic Conflicts ◽  
Probability Prediction

At unsignalized intersections, left-turning vehicles from minor road approach are more likely to be involved in traffic conflicts and traffic crashes and are one of the most leading factors impacting traffic efficiency and capacity. The authors of the paper observed that some drivers behaved illegally and dangerously while performing left turns from minor road approach, resulting in abnormal trajectories at unsignalized intersections. By applying binary logistic analysis, a probability prediction model was developed to explore various factors affecting probability of normal path taken by drivers while turning left from minor road approach. Based upon the model, measures such as lowering running speeds of vehicles on major road or minor road and adding more lanes on minor road can be used to encourage more drivers to take normal vehicle paths, which is helpful for the improvement of traffic safety, efficiency, and capacity. Results of the paper can be used for the guidance of design and management of unsignalized intersections.

Delays to road traffic at an intersection

1964 ◽  
Vol 1 (2) ◽  
pp. 297-310 ◽  
Author(s):  
G. F. Yeo ◽  
B. Weesakul
Keyword(s):  
Road Traffic ◽  
Partial Solution ◽  
Major Road ◽  
Gap Acceptance ◽  
Road Vehicle ◽  
Mean Delay ◽  
Minor Road ◽  
The Mean ◽  
Stationary Waiting Time ◽  
A Minor

A model for road traffic delays at intersections is considered where vehicles arriving, possibly in bunches, in a Poisson process in a one way minor road yield right of way to traffic, which forms alternate bunches and gaps, in a major road. The gap acceptance times are random variables, and depend on whether or not a minor road vehicle is immediately following another minor road vehicle into the intersection or not.The transforms of the stationary waiting time and queue size distributions, and the mean stationary delay, for minor road vehicles are obtained by substitution of determined service time distributions into results for a generalisation of the M/G/1 queueing system. Some numerical results are given to illustrate the increase in the mean delay for variable gap acceptance times for a Borel-Tanner distribution of major road traffic, and a partial solution is given for a two way major road.

scholarly journals GAP ACCEPTANCE FOR LEFT TURNS FROM THE MAJOR ROAD AT UNSIGNALIZED INTERSECTIONS

Transport ◽  
2014 ◽  
Vol 32 (3) ◽  
pp. 252-261 ◽  
Author(s):  
Hongmei Zhou ◽  
John N. Ivan ◽  
Per E. Gårder ◽  
Nalini Ravishanker
Keyword(s):  
Information Criterion ◽  
Time Interval ◽  
Major Road ◽  
Gap Acceptance ◽  
Acceptance Probability ◽  
Left Turn ◽  
Unsignalized Intersections ◽  
The Mean ◽  
And Gender ◽  
Gap Models

This paper attempts to identify factors that may influence the gap acceptance behavior of drivers who turn left from the major road at unsignalized intersections. Drivers’ accepted and rejected gaps as well as their age and gender were collected at six unsignalized intersections with both two and four lanes on the major road, with and without the presence of a Left-Turn Lane (LTL), and with both high and low Speed Limits (SLs). Whether or not a driver accepts a given gap was considered as a binary decision and correlated logit models were used to estimate the probability of accepting a gap. Models with different factors were tested and the best model was selected by the quasi-likelihood information criterion. The gap duration, the number of rejected gaps, the mean and total time interval of the rejected gaps and the gender of the driver were all significant in explaining the variation of the gap acceptance probability, whereas the number of lanes of the major road, the presence of LTL, the SL and the driver’s age category were not. Gap acceptance probability functions were determined based on the best model, including both the factors of the number of rejected gaps and the mean time interval of the rejected gaps. As the values of these two factors increase, the probability of accepting a given gap rises up. The developed model can be further applied in practice to improve the analysis of traffic operations and capacity at unsignalized intersections.

Gap-acceptance in road traffic

1968 ◽  
Vol 5 (1) ◽  
pp. 84-92 ◽  
Author(s):  
A. G. Hawkes
Keyword(s):  
Simple Model ◽  
Service Time ◽  
Time Distribution ◽  
Road Traffic ◽  
Service Time Distribution ◽  
Major Road ◽  
Gap Acceptance ◽  
Road Vehicles ◽  
Minor Road ◽  
Acceptance Function

We find the distribution of delay to minor road vehicles waiting to merge or cross a single stream of major road traffic. The decision to cross is taken on the basis of a gap-acceptance function. The model turns out to be a simple queueing problem in which a customer finding an empty queue has a different service time distribution from queueing customers. The key to this representation is given in Section 3. Some numerical results in Section 6 indicate that in most circumstances a simple model will give adequate results.

Gap-acceptance in road traffic

1968 ◽  
Vol 5 (01) ◽  
pp. 84-92 ◽  
Author(s):  
A. G. Hawkes
Keyword(s):  
Simple Model ◽  
Service Time ◽  
Time Distribution ◽  
Road Traffic ◽  
Service Time Distribution ◽  
Major Road ◽  
Gap Acceptance ◽  
Road Vehicles ◽  
Minor Road ◽  
Acceptance Function

We find the distribution of delay to minor road vehicles waiting to merge or cross a single stream of major road traffic. The decision to cross is taken on the basis of a gap-acceptance function. The model turns out to be a simple queueing problem in which a customer finding an empty queue has a different service time distribution from queueing customers. The key to this representation is given in Section 3. Some numerical results in Section 6 indicate that in most circumstances a simple model will give adequate results.

scholarly journals Reliability Analysis of Sight Distance for Stopcontrol Intersections on Horizontal Alignments

2021 ◽  
Author(s):  
Altaf Hussain
Keyword(s):  
Extreme Values ◽  
Safety Margin ◽  
Random Variable ◽  
Probability Of Failure ◽  
Major Road ◽  
Road Design ◽  
Sight Distance ◽  
Minor Road ◽  
Reliability Method ◽  
Design Speed

Intersection sight distance (ISO) for stop-control intersections refers to the provision of adequate sight distance between a minor-road stopped vehicle and a major-road vehicle. The AASHTO policy for ISO for intersections on straight roadways Is based on the extreme values of the component design variables, such as major-road design speed and time gap, and assumes that these variables are deterministic. This research presents a reliability method that considers the moments (mean and variance) of the probability distribution of each random variable instead of the extreme values. This reliability method also accounts for the correlations among the component random variables. A performance function in terms of a safety margin is defined as the difference between the expected available and expected required ISO. Relationships for the mean and standard deviation of the safety margin are developed using First- Order Second-Moment analysis. Design graphs for the obstruction location are established for different radii of horizontal curves, design speed, and probability of failure. The reliability method is very useful as it provides the reliability associated with I8D design values. For evaluation purposes, the method can be used to determine the probability of failure of a particular intersection for an existing obstruction and current traffic conditions. The method can also be used to design the obstruction location for a given probability of failure. It was found that the deterministic method generally provides a higher probability of failure when the obstruction is closer to the minor road.

A Flexible Multi-Modal Multi-User Traffic Simulation for Studying Complex Road Design

2020 ◽  
Author(s):  
Jack Miller ◽  
Vijay Kalivarapu ◽  
Michael Holm ◽  
Tor Finseth ◽  
Jordan Williams ◽  
...  
Keyword(s):  
Autonomous Vehicles ◽  
Traffic Accidents ◽  
Traffic Simulation ◽  
User Behavior ◽  
Low Cost ◽  
Simulation Platform ◽  
Commodity Hardware ◽  
Monitor Display ◽  
Head Mounted Display ◽  
Road Design

Abstract While there are many factors that affect traffic accidents, safe road design plays a key role. It is critical to understand traffic flow and driver response to various scenarios. Furthermore, with the inclusion of new traffic trends such as bicycle friendly roads and autonomous vehicles, it is ever more important to study the complex relationships between traffic entities. However, controlled experiments can be difficult to implement in the real world. Traffic simulation has been researched for decades to understand the flow of traffic in a variety of environments and how users interact within it. However, these platforms are limited in simulation and authoring capabilities, do not allow for multiple human agents, or are not accessible by roadway designers. This research explores the technical development of a multi-user multi-modal traffic simulation platform that expands on the capabilities of traditional traffic simulators. Traffic simulation of virtual cars and pedestrian agents were generated through VISSIM and networked into a simulation platform. Multiple human agents can interface with the system through a physical car and bicycle rig featuring both a virtual reality head mounted display and a multi-monitor display. Furthermore, the multi-user nature of the platform allows for a variety of complex research applications including multi-user behavior. By utilizing low-cost commodity hardware and software, the accessibility of this platform is greatly increased. A testbed environment was created to evaluate the technical limitations of the platform and assess where further work is needed. Through this evaluation, the authoring process and networking capabilities were optimized. Additionally, the core functionality of the platform, including the various simulator modes and multi-user functionality, was found to be successful. Through this research, combining commodity hardware with traffic simulation will allow a larger number of researchers to better understand traffic environments and how humans may interact within them.

Delays to road traffic at an intersection

1964 ◽  
Vol 1 (02) ◽  
pp. 297-310 ◽  
Author(s):  
G. F. Yeo ◽  
B. Weesakul
Keyword(s):  
Road Traffic ◽  
Partial Solution ◽  
Major Road ◽  
Gap Acceptance ◽  
Road Vehicle ◽  
Mean Delay ◽  
Minor Road ◽  
The Mean ◽  
Stationary Waiting Time ◽  
A Minor

A model for road traffic delays at intersections is considered where vehicles arriving, possibly in bunches, in a Poisson process in a one way minor road yield right of way to traffic, which forms alternate bunches and gaps, in a major road. The gap acceptance times are random variables, and depend on whether or not a minor road vehicle is immediately following another minor road vehicle into the intersection or not. The transforms of the stationary waiting time and queue size distributions, and the mean stationary delay, for minor road vehicles are obtained by substitution of determined service time distributions into results for a generalisation of the M/G/1 queueing system. Some numerical results are given to illustrate the increase in the mean delay for variable gap acceptance times for a Borel-Tanner distribution of major road traffic, and a partial solution is given for a two way major road.

Sign in / Sign up

Export Citation Format

Share Document