Author: Mohammed Obeidat
Publisher:
ISBN:
Category : Reflective materials
Languages : en
Pages : 128
Get Book Here
Book Description
Roadway guide sign visibility during darkness is fundamental to driver safety, especially elderly drivers. Guide sign visibility can be improved by external sign illumination or the use of retroreflective sheeting on signs. Because energy conservation is essential in the midst of a worldwide energy crisis, various Departments of Transportation have investigated usage of energy-efficient lighting technology with overhead guide signs. This report presents results of a survey related to overhead sign lighting usability by states, a laboratory experiment to compare the light distribution of five light sources used to illuminate overhead guide sign by several states, a cost analysis for the tested light sources, a field experiment to compare the visibility of three retroreflective sheeting used by states, a cost analysis for the tested retroreflective guide signs, and an analysis by determining the most cost-effective method of increasing overhead guide sign visibility to drivers during nighttime. A laboratory experiment was conducted to compare the light distribution of three conventional light sources: Metal Halide, Mercury Vapor, and High Pressure Sodium, and two new generation light sources: Induction lighting, and Light Emitting Diode. Combining two decision criteria, the light distribution and the cost, resulted in finding the Induction lighting to be the recommended light source for those states that want to continue illuminating their overhead guide signs. A field experiment was conducted to compare three types of sign sheeting, Engineering Grade (type I), Diamond Grade (type XI), and High Intensity (type IV), in order to determine the sign sheeting material that best improves sign visibility. Combining the decision criteria to compare these three retroreflective sheeting, the visibility and the cost, High Intensity (type IV) is the recommended sign to be used by DOTs, followed by Diamond Grade (type XI). In comparing the best options used to increase sign visibility, sign illumination and sign retroreflectivity, it is found that using retroreflective sheeting is more cost effective than sign illuminating.
Author: Paul John Carlson
Publisher:
ISBN:
Category : Traffic signs and signals
Languages : en
Pages : 84
Get Book Here
Book Description
Chapter 1. Introduction -- chapter 2. Background -- chapter 3. Closed-course study -- chapter 4. Open-Road study -- chapter 5. Research findings -- References -- appendix A. Incremental effects of light sources and sign sheeting on legend luminance for overhead guide signs -- appendix B. Assessment of background complexity using digital images of roadway scenes by image processing -- appendix C. Open-road study details -- appendix D. Guidelines for Nighttime overhead sign visibility.
Author: Mohammed Obeidat
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
This dissertation is the result of studying different methods of increasing guide sign visibility and legibility to drivers during nighttime, to increase safety on roadways. It also studies intersection lighting to indicate the lighting benefits on nighttime crash frequency reduction. From a survey conducted, practices related to overhead guide sign illumination and retroreflectivity in United States were summarized. A laboratory experiment was conducted to compare light distribution of five light sources: Metal Halide, Mercury Vapor, High Pressure Sodium, induction lighting, and Light Emitting Diode (LED). Cost analysis of the five light sources was performed. Combining results of the laboratory experiment and the cost analysis, induction lighting was recommended for states that want to continue external sign illumination. A retroreflectivity experiment was conducted to compare three types of retroreflective sheeting: Engineering Grade (type I), Diamond Grade (type XI), and High Intensity (type IV), to determine the sheeting that best increases visibility and legibility. Diamond Grade (type XI) was found to be the optimal sheeting that increases visibility and legibility to drivers during nighttime. A glare experiment was conducted to expand the retroreflectivity experiment results. Four sheeting-font combinations of High Intensity (type IV) and Diamond Grade (type XI) materials and Series E (Modified) and Clearview fonts were compared. Results revealed an optimal sheeting-font combination of Diamond Grade (type XI) sheeting and Clearview font which increases the visibility and legibility of guide signs to drivers under presence of oncoming glare source. The Highway Safety Information System (HSIS) database was used to study the effect of intersection lighting on the expected crash frequency. Illuminated intersections showed 3.61% and 6.54% decrease in the expected nighttime crash frequency as compared to dark intersections in Minnesota and California, respectively. In addition, partial lighting at intersections decreases the expected nighttime crash frequency by 4.72% compared to continuous lighting in Minnesota. The recommended sheeting-font combination for Departments of Transportation was Diamond Grade (type XI) and Clearview. This combination will increase signs' visibility and legibility to drivers, and consequently increase safety on roadways. Adding partial lighting at intersections will reduce the expected nighttime crash frequency, and increase safety on roadways.
Author: American Association of State Highway and Transportation Officials. Task Force for Roadside Safety
Publisher:
ISBN:
Category : Roads
Languages : en
Pages : 560
Get Book Here
Book Description
Author:
Publisher:
ISBN:
Category : Automobile driving at night
Languages : en
Pages : 60
Get Book Here
Book Description
This manual deals with the reflectivity of traffic signs. It interprets and explains the specifications and test procedures in the standard specifications for construction of roads and bridges on federal highway projects (fp-85) dealing with retroreflective sheeting and related matters and provides guidance where appropriate. Topics covered include: 1) principles of retroreflection and characteristics of sign reflective sheeting. 2) Considerations in selecting different sheeting types. 3) Fp-85 specifications and test procedures. 4) Sign fabrication. 5) Handling, stockpiling, and installing. 6) Inventory, inspection, and replacement. 7) Maintenance.
Author: Aditya Gund
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Before year 2012 the US States must implement and continue using an assessment or management method to maintain traffic signs' retro-reflectivity at or above the minimum levels adopted by FHWA. Overhead guide signs are a particular problem because past research has shown that with available sheeting types, external illumination may still be necessary. Newer sheeting types and more energy efficient and cost-effective lighting systems are currently available. Over the next several years there is potential for savings of tens of thousands of dollars if the states don't have to use external illumination for their overhead guide signs, or, if more energy efficient, low cost lighting systems are used when necessary. A detailed literature review was conducted on minimum retro-reflectivity values for overhead guide signs, the legibility distance under reduced sign luminance and the lighting systems available for external illumination. There is no agreement found in the previous research studies as to what is the optimum or minimum luminance of the guide signs. In addition, a survey was sent to all state DOTs. This survey was focused on finding states' policies regarding the use of sheeting type and external illumination requirement, and methods and lighting systems for maintaining minimum values for overhead guide sign luminance. The total response rate was 56% (28 out of 50 state DOTs responded). Out of 28 respondents 19 said that they have usage policy for the type of sheeting material used for overhead guide signs and 18 of them provided details about their policy. An equipment to control the illumination levels from vehicle headlamps was built and pilot tests were conducted in the laboratory. A pulse-with-modulation dimming circuit designed around the Atmel ARM-based microcontroller board and power MOSFETs was used to control the brightness of the headlights for the high- and low-beams. Field tests were conducted in the later stages during nighttime to evaluate three different types of sheeting materials using 10 human subjects from age group 18-34. The materials DG3 and Type IV were found to perform better than Type I material for nighttime visibility but they were not significantly different from each other.
Author: Paul John Carlson
Publisher:
ISBN:
Category : Reflectance
Languages : en
Pages : 110
Get Book Here
Book Description
Author: Hugh W. McGee
Publisher: Transportation Research Board
ISBN: 9780309049023
Category : Transportation
Languages : en
Pages : 52
Get Book Here
Book Description
This synthesis will be of interest to traffic engineers, planners, and others interested in making sure that motorists' needs for directional information on freeways are being met. Information is provided on policies and procedures used by states in evaluating freeway guide signs and replacing those that are outdated or deteriorated. Many signs on freeways and other controlled-access highways have exceeded their service life and are no longer serving motorists' needs. This report of the Transportation Research Board describes the policies, proceduress, and criteria used by states for freeway sign evaluation and replacement programs.
Author: Andrew J. Holick
Publisher:
ISBN:
Category : Reflectance
Languages : en
Pages : 52
Get Book Here
Book Description
Author: R. G. McMillan
Publisher:
ISBN:
Category : Reflectors (Safety devices)
Languages : en
Pages : 32
Get Book Here
Book Description
