Safety Evaluation for the Highway Alignment with 3D Visual Simulation

2012 ◽  
Vol 182-183 ◽  
pp. 1131-1134
Author(s):  
Xiao Jia Chen ◽  
Yi Cheng Luo
Keyword(s):  
Safety Evaluation ◽  
Visual Simulation ◽  
Horizontal Curve ◽  
Current Standard ◽  
Highway Design ◽  
Standard Requirement ◽  
Sight Distance ◽  
Real Scene ◽  
A Minor ◽  
Highway Alignment

In the current highway design, poor coordinate of the alignment has a great effect on the sight distance which would increase the danger and difficulty of driving. For this reason, safety checking for highway alignment is required by the current standard. In this paper, 3D simulation technique was used to model the real scene of driving. Based on the concept of the preview sight distance (PVSD), two typical coordinates of alignment in practice were discussed. Although the current standard requirement is met, it is demonstrated that the alignment in the location of a minor horizontal curve and combination of a tangent with a circular curve could still provide driver confusing information. Some recommendations were suggested so as to improve the highway alignment design.

Sight distance red zones on combined horizontal and sag vertical curves

1998 ◽  
Vol 25 (4) ◽  
pp. 621-630 ◽  
Author(s):  
Yasser Hassan ◽  
Said M Easa
Keyword(s):  
Quantitative Analysis ◽  
Three Dimensional ◽  
The Other ◽  
Two Dimensional ◽  
Horizontal Curve ◽  
Sight Distance ◽  
Stopping Sight Distance ◽  
Three Dimensional Models ◽  
Highway Alignment ◽  
Current Standards

Coordination of highway horizontal and vertical alignments is based on subjective guidelines in current standards. This paper presents a quantitative analysis of coordinating horizontal and sag vertical curves that are designed using two-dimensional standards. The locations where a horizontal curve should not be positioned relative to a sag vertical curve (called red zones) are identified. In the red zone, the available sight distance (computed using three-dimensional models) is less than the required sight distance. Two types of red zones, based on stopping sight distance (SSD) and preview sight distance (PVSD), are examined. The SSD red zone corresponds to the locations where an overlap between a horizontal curve and a sag vertical curve should be avoided because the three-dimensional sight distance will be less than the required SSD. The PVSD red zone corresponds to the locations where a horizontal curve should not start because drivers will not be able to perceive it and safely react to it. The SSD red zones exist for practical highway alignment parameters, and therefore designers should check the alignments for potential SSD red zones. The range of SSD red zones was found to depend on the different alignment parameters, especially the superelevation rate. On the other hand, the results showed that the PVSD red zones exist only for large values of the required PVSD, and therefore this type of red zones is not critical. This paper should be of particular interest to the highway designers and professionals concerned with highway safety.Key words: sight distance, red zone, combined alignment.

Research of Highway Alignment Design Safety Evaluation Using Curvature Change Rate

2012 ◽  
Vol 238 ◽  
pp. 493-496
Author(s):  
Sheng Neng Hu
Keyword(s):  
Traffic Safety ◽  
Road Traffic ◽  
Design Method ◽  
Selection Index ◽  
Safety Evaluation ◽  
Highway Design ◽  
Change Rate ◽  
Evaluation Standard ◽  
Road Traffic Safety ◽  
Highway Alignment

Aiming at the disadvantages of traditional design method of highway alignment and existent problems including subjectivity, reliability index, comprehensive, applicability etcetera in highway alignment evaluation with running speed. On the basis of the “safety first” idea for highway design, the concept of change rate of curvature has been proposed. Curvature change rate is the clear factor impacting on road traffic safety. Road quality evaluation standard is established based on the curvature change rate and its application method in highway alignment design method. The method not only effectively evaluates highway alignment quality, but also may be used as the basis for the selection index of highway geometric design.

Three-Dimensional, Probabilistic Highway Design

2008 ◽  
Vol 2060 (1) ◽  
pp. 10-18 ◽  
Author(s):  
Mohamed Sarhan ◽  
Yasser Hassan
Keyword(s):  
Reliability Analysis ◽  
Probabilistic Approach ◽  
Three Dimensional ◽  
Design Parameters ◽  
Horizontal Curve ◽  
Vertical Alignment ◽  
Highway Design ◽  
Side Slope ◽  
Sight Distance ◽  
Stopping Sight Distance

The potential usefulness of reliability analysis has recently been stressed in many engineering applications. Given the variability in the design parameters, a reliability-based probabilistic approach is well suited to replace the current deterministic highway design practice. However, progress in this regard is generally slow. In this study, the reliability analysis was used to estimate the probability of hazard (POH) that might result from insufficiency of sight distances. As an application, the available sight distance was checked against required stopping sight distance on an assumed road segment. Variation of the design parameters was addressed with Monte Carlo simulation using 100,000 sets of design parameters based on distributions available in the literature. A computer program was developed to use these sets of design parameters to calculate the profiles of available and required stopping sight distances in two- and three-dimensional projections as well as the profile of POH. The approach was applied to a horizontal curve overlapping with flat grade, crest curves, and sag curves in a cut section where the side slope would restrict the sightline. The analysis showed that the current deterministic approach yields very conservative estimates of available and required stopping sight distance, resulting in very low POH. The application example also showed the change of POH with the change of vertical alignment parameters.

The Stopping Sight Distance Test for Freeway Based on the Operating Speed

2011 ◽  
Vol 97-98 ◽  
pp. 180-184
Author(s):  
Yue Zhang
Keyword(s):  
Safety Evaluation ◽  
Operating Speed ◽  
Horizontal Curve ◽  
Passenger Car ◽  
Sight Distance ◽  
Stopping Sight Distance

In this paper, the stopping sight distance of passenger car based on the operating speed was regarded as guideposts, and its corresponding radius of horizontal curve and vertical curve was got according to the calculated results, and available for reference and application in the alignment design and safety evaluation for freeway.

Evaluation of Highway Alignment Safety Design Based on Operating Speed

2012 ◽  
Vol 594-597 ◽  
pp. 1463-1466
Author(s):  
Sheng Neng Hu ◽  
Pan Qiu ◽  
Qin Dong Fan ◽  
Zhong Huang Hu
Keyword(s):  
Design Method ◽  
Safety Evaluation ◽  
Observation Data ◽  
Vehicle Speed ◽  
Highway Design ◽  
The Road ◽  
Road Design ◽  
Design Coordination ◽  
Safety Design ◽  
Highway Alignment

Highway safety is one of the targets of the road design, coordination of highway design index and the actual vehicle speed is the key. According to the analysis of automobile speed observation data, established the plain or hilly area two road car model, put forward highway alignment design safety evaluation standards and safety design method.

Development and Adoption of Early AASHO Design Criteria

1998 ◽  
Vol 1612 (1) ◽  
pp. 26-33 ◽  
Author(s):  
Jerome Hall ◽  
Daniel Turner
Keyword(s):  
Design Parameters ◽  
Design Criteria ◽  
Adoption Process ◽  
Horizontal Curve ◽  
Highway Design ◽  
Initial Development ◽  
Design Processes ◽  
Blue Book ◽  
Curve Design ◽  
Independent Design

The conception, development, and adoption of early AASHO highway design criteria are documented. Examining the early efforts states used to select a design vehicle and develop horizontal curve design criteria illustrates why AASHO’s leadership was necessary. AASHO’s slow and somewhat haphazard criteria development, and the disparity from state to state, demonstrated the need for a national consensus in highway design parameters. AASHO’s role in providing these criteria is outlined through its initial development of policy booklets, followed by its 1954 publication of the landmark Blue Book. The processes by which nine states adopted the AASHO guidance are briefly reviewed. In several cases, the AASHO policy was embraced immediately, and in others it was accepted slowly as states clung to their independent design processes and only gradually updated their design criteria. A few simple conclusions are drawn about the development and adoption process, particularly as it may relate to tomorrow’s highway design criteria.

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.

Age and Driver Time Requirements at Intersections

1994 ◽  
Vol 38 (14) ◽  
pp. 842-846 ◽  
Author(s):  
Neil Lerner
Keyword(s):  
Age Groups ◽  
Older Drivers ◽  
Forward Movement ◽  
Highway Design ◽  
Sight Distance ◽  
Stop Sign ◽  
Objective Evidence ◽  
Time Requirements ◽  
Computer Controlled ◽  
Older Subjects

Current highway design models for required sight distance at stop-sign controlled intersections assume that the perception-reaction time (PRT) required is 2.0 seconds. That is, a 2.0 second interval to perceive, evaluate, decide, and initiate a response, is adequate to cover the range of time it takes real drivers to do this. This experiment evaluated the adequacy of the 2.0 second PRT assumption, including specific consideration of older drivers, who are known to experience relatively greater difficulty at intersections. Subjects in three age groups (20–40; 65–69; and 70+ years old) drove their own vehicles (fitted with a computer-controlled video-based data collection system) over a route that included 14 stop-controlled intersections. At each stop sign, they were required to make ratings of “road quality;” this broke visual search, and provided an opportunity for the experimenter to precisely define the initiation of search and the initiation of forward movement (thus defining PRT). The 2.0 second PRT assumption was found to work reasonably well for all age groups, and corresponded to roughly the 85th percentile PRT for all subjects. PRTs for older subjects were slightly (but significantly) briefer than for younger drivers. Reasons for not observing a slowing of intersection PRT with advancing age are discussed. The findings are also compared to gap acceptance data from another experiment. Even though the present experiment did not find objective evidence of older drivers requiring longer decision times, older subjects nonetheless demanded longer gaps in traffic in order to judge it safe to enter traffic.

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