2013 Session: 312

• Evaluation of the Impact of Modern Headlamp Technology on Sag Vertical Curve Design Criteria
  Abstract: This paper includes a review of the current methodologies used in the design of sag vertical curves, a review of the changes in headlamp technologies, the results of the survey of practitioners, two visibility experiments, and conclusions.The review of the headlamp technology shows that, over time, headlamp technologies have had increasing limitation on the amount of light emitted above the horizontal axis of the headlamp. In addition to the regulatory impact, headlamp technologies such as visually-optically aligned technologies also limit uplight. In the practitioner survey, it was found that very few deviations from the AASHTO design methodologies were used. Based on the practitioner review, the potential to modify the current methodologies is limited to the manipulation of the vehicle speed, deceleration, and the angle of curvature change.The results of the visibility experiments found that participants detected objects at distances which were significantly shorter than the safe stopping distance (SSD). This occurred not only in sag vertical curves, but also on flat roadway. This indicated that even if sag vertical curves were redesigned, visibility distance would still be shorter than SSD because the headlamps would be the limiting factor. A review of the potential modifications to sag vertical curve designs (which were suggested as a result of the practitioner survey) found that these changes would be inadequate to make up the difference between visibility distance and SSD.
  Authors: Gibbons, Ronald B.; Medina Flintsch, Alejandra; Williams, Brian; Du, Jianhe; Rakha, Hesham
  Authors: Gibbons, Ronald B.; Medina Flintsch, Alejandra; Williams, Brian; Du, Jianhe; Rakha, Hesham
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management; Safety and Human Factors; Vehicles and Equipment
  Session: 312
  Paper Number: 13-3815
• Applying Sign Luminance Computation Model to Study Effects of Other Vehicles on Sign Luminance
  Abstract: As one external lighting source on the road, headlamps from adjacent vehicles in the stream traffic should not be ignored. No comprehensive study has yet been developed for exploring the influence of sign luminance produced by other vehicle headlamps. In this paper, a luminance calculation model is developed to calculate sign luminance from all potential headlamps in the stream traffic. Using the model, four main scenarios have been simulated to analyze the effects of the positions of the target vehicle and other vehicles, vehicle type, sign type and sheeting material on the sign luminance. In addition, occlusion between vehicles is also addressed in the paper, by calculating the minimum distances between vehicles for the headlamps and for the driver’s view of the following vehicle when vehicles and the sign are and are not in the same lane.
  Authors: Ye, Fan; Carlson, Paul J.; Brimley, Bradford
  Authors: Ye, Fan; Carlson, Paul J.; Brimley, Bradford
  Year: 2013
  Document Type: Paper
  Subject: Operations and Traffic Management; Safety and Human Factors; Vehicles and Equipment
  Session: 312
  Paper Number: 13-4894
• Evaluation of the Impact of Modern Headlamp Technology on Sag Vertical Curve Design Criteria
  Authors: Gibbons, Ronald
  Authors: Gibbons, Ronald
  Year: 2013
  Document Type: Presentation
  Subject: Operations and Traffic Management; Safety and Human Factors; Vehicles and Equipment
  Session: 312
  Paper Number: 13-3815
• Applying Sign Luminance Computation Model to Study Effects of Other Vehicles on Sign Luminance
  Authors: Ye, Fan
  Authors: Ye, Fan
  Year: 2013
  Document Type: Presentation
  Subject: Operations and Traffic Management; Safety and Human Factors; Vehicles and Equipment
  Session: 312
  Paper Number: 13-4894
• Glare-Free High-Beam Systems
  Authors: Neumann, Rainer
  Authors: Neumann, Rainer
  Year: 2013
  Document Type: Presentation
  Subject: Operations and Traffic Management; Safety and Human Factors; Vehicles and Equipment
  Session: 312
  Paper Number: P13-5673
• Vehicle Headlight Standards: Specifying Safety-Related Performance
  Authors: Terburg, Bart
  Authors: Terburg, Bart
  Year: 2013
  Document Type: Presentation
  Subject: Operations and Traffic Management; Safety and Human Factors; Vehicles and Equipment
  Session: 312
  Paper Number: P13-5674