Author: R. N. Robertson Publisher: ISBN: Category : Languages : en Pages : 58
Book Description
The current practice in Virginia is to reflectorize and illuminate all overhead highway signs because of their important role in the safe and orderly flow of traffic. Reflectorization is obtained by using reflective sheeting as background and legend materials, and diffuse illumination is provided on the sign surface by lighting fixtures. The performance of the high intensity sheeting has shown significant promise and the purpose of this research was to determine the feasibility of using the material on overhead highway signs without external illumination. Since sign brightness standards have not been established, a comparative technique was employed whereby the brightness of six high intensity overhead signs without illumination was compared to that of six conventional illuminated signs. All experimentation was conducted in the field under the physical and environmental conditions experienced by the highway user. Luminance measurements were made with a telephotometer at the driver's eye position of eleven conventional automobiles. A total of 5,446 luminance measurements were recorded from the travel lanes of illuminated and non-illuminated roadways. The study concluded that the unlighted high intensity signs were brighter than the lighted conventional signs for the motorist traveling on straight sections of roadways using high beam headlights. For the same motorist using low beams the luminances of the high intensity signs were not as bright as those of adjacent conventional signs. Under stream traffic conditions, the average luminances of the conventional signs were slightly higher than those of the unlighted high intensity signs, however, in many cases there were no statistical differences and the people who viewed the signs stated they preferred the high intensity sign because its uniform brightness provided better legibility. On a curved approach, where only a limited amount of light from the vehicles was projected upon the overhead signs, the brightness of the unlighted high intensity signs was not sufficient to provide the motorists with sign visibility and legibility equivalent to those obtained from the lighted conventional signs.
Author: H. Dexter Jones Publisher: ISBN: Category : Traffic signs and signals Languages : en Pages : 132
Book Description
Verhead Guide Signs can be illuminated to sufficient target value and uniformity with certain 100 watt mercury vapor lighting units. Coating materials based on thermal setting polyester, and thermal setting polyvinylidene fluoride have been found to be satisfactory coating materials for Overhead Guide Signs. Preliminary field evaluations and legibility studies indicate that approximately 40% of the Overhead Guide Signs in the State would not require illumination if the legend is reflective.
Author: Jonathan Everett Upchurch Publisher: ISBN: Category : Roads Languages : en Pages : 108
Book Description
The study objective was to identify a lighting system which has a lower power cost and reduced maintenance requirements and which provides adequately for motorists' needs in terms of legibility and illumination level. Twenty-five candidate lighting systems were identified through a review of technical data and specifications for lamps and fixtures by an independent lighting expert. Photometric tests and computer analyses of sign illumination levels reduced the number of candidates to ten alternative systems which were then field tested. Each alternative lighting system was tested for 10 to 14 months. Sign luminance was measured with a telephotometer. Power consumption was monitored. Maintenance requirements and lamp life were noted. A human factors study determined legibility distance and rated viewing comfort, lighting uniformity, and color rendition. An economic analysis was performed which considered the initial cost of acquiring and installing the lighting systems and annual costs for electric power, washing, relamping, and ballast replacement. A lighting system using the high pressure sodium light source was recommended. Compared to the existing commonly used fluorescent system, it uses one-third as much electric power and has about one-third of the annual owning and operating cost. The recommended system has a satisfactory illumination level and provides the best legibility distance of the ten systems tested.
Author: United States. Federal Highway Administration. Implementation Division Publisher: ISBN: Category : Traffic signs and signals Languages : en Pages : 58
Book Description
Combined state studies: Arkansas State Highway and Transportation Dept., Florida Dept. of Transportation, Kentucky Dept. of Transportation, and Federal Highway Administration.
Author: R. N. Robertson
Author: 
Author: H. Dexter Jones
Author: 
Author: Jonathan Everett Upchurch
Author: United States. Federal Highway Administration
Author: Norman Bryan
Author: United States. Federal Highway Administration. Implementation Division
Author: Donald A. Gordon
Author: H. Dexter Jones