Merrill J. Allen

Actual pedestrian visibility and the pedestrian's estimate of his own visibility.

ABSTRACT Over 1,700 observations were made on the road involving actual pedestrians and cars, to test three factors of pedestrian visibility. Of 26 pedestrian observers, ages 18‐35, the one pedestrian most pessimistic about his visibility closely estimated his true visibility of 175 feet. Each of the remaining 25 pedestrians estimated his visibility to be up to three times farther than it actually was. The average pedestrian thought he was visible at 343 feet. Actual pedestrian visibility was enhanced from about 175 feet for normal dark clothing to about 790 feet by using reflectorized clothing. In the presence of headlight glare, black clothing was seen at about 167 feet while the reflectorized clothing was seen at 680 feet. The clothing was reflectorized with a 1″ fabric tape outlining the collar and wrapped around the sleeves. The reflectance of the tape was 50 candles/ft2/ft candle of incident light.

The ability to see a pedestrian at night: the effects of clothing, reflectorization and driver intoxication

ABSTRACT In the United States, pedestrian deaths account for nearly 20% of all traffic fatalities. During darkness the pedestrians risk is increased. This risk is further increased if a pedestrian is wearing dark clothing or must travel on a roadway concurrently with a driver who has been drinking. In the laboratory phase of this study it was found that at low levels of illumination an individuals sensitivity to contrast decreases as his blood alcohol level increases. All subjects exhibited a significant (p <.01) decrease in contrast sensitivity at blood alcohol levels greater than 0.04%. In the road test phase of the study visibility distances were found to be unacceptably short for “dummy” pedestrians covered with black or gray fabric. Dummies covered with white fabric were safely visible for a driver traveling up to a speed of 50 M.P.H.; however, only reflectorized dummies were safely visible above that speed. At blood alcohol levels greater than 0.04% all of the observers exhibited a significant (p <.01) decrease in the mean visibility distance for each of the simulated pedestrian conditions.

Color Defective Drivers and Safety

At least seven million drivers in North America cannot reliably identify red and green lights. The common assumption by traffic authorities that no serious problems exist is contradicted by the data on color vision, the testimonies of color defective drivers, studies under controlled conditions, and by reliable accident statistics. Color defective drivers can be provided with the same measure of traffic light safety as for normals. Brake lights on vehicles can be made equally effective for color defectives. Suggestions are provided to help those with color defective vision to compensate for their problems.

AUTOMOBILE WINDSHIELDS, SURFACE DETERIORATION

ABSTRACT Thirteen used windshields from General Motors automobiles were randomly selected for test. Code monograms on each indicated they probably were the original equipment windshields. Photographs were made through each of the scattered light surrounding automobile headlights. Damage from windshield wiper action seemed to be related to miles of travel. Damage from hand cleaning and ice scraping operations was unrelated to age in this small sample. Pitting from small high velocity particles also showed up. On a subjective rating scale, 8 of the 13 windshields were judged to be damaged enough to cause a noticeable increase in glare, especially at night, and to warrant consideration of replacement with a new windshield. Four were judged to be unsafe for night driving.

DAYTIME AUTOMOBILE WINDSHIELD AND DASH PANEL CHARACTERISTICS

DURING THE SUMMER OF 1962, A STUDY OF WINDSHIELD AND INSTRUMENT PANEL LIGHT REFLECTANCE CHARACTERISTICS WAS CONDUCTED ON AUTOMOBILES OF SEVERAL MANUFACTURERS FOR 1959 THROUGH 1962. FIFTY-SIX AUTOMOBILES WERE PHOTOGRAPHED AND MEASURED FOR DAYTIME WINDSHILD LIGHT TRANSMISSION, AMOUNT OF DIRT ON WINDSHIELD, INSTRUMENT PANEL LUMINANCE LEVELS AND VERTICAL SIZE OF SPEEDOMETER AND ODOMETER NUMERALS. PHOTOGRAPHS ARE USED TO SHOW VARIATIONS IN PANEL DESIGN AND TO GIVE EVIDENCE OF EXCESSIVE WINDSHIELD REFLECTANCE. SPECIFIC, PRACTICAL AND ECONOMIC RECOMMENDATIONS FOR CHANGES IN THE VISUAL ENGINEERING DEFECTS OF CURRENT MODELS ARE MADE IN THE TEXT. CONCLUSIONS REACHED WERE THAT: (1) ALL OF THE FIFTY-SIX 1956-1962 AUTOMOBILES TESTED HAD SERIOUS FAULTS SO FAR AS THE VISIBILITY OF THE HIGHWAY AND THE INSTRUMENT PANEL IN THE DAYTIME IS CONCERNED. (2) THE AMOUNT OF LIGHT REFLECTED FROM THE TOP OF THE DASH ONTO THE WINDSHIELD AND INTO THE EYES OF THE DRIVER AVERAGES OVER 15% OF THE AVERAGE SCENE LUMINANCE, (3) THE AMOUNT OF LIGHT SCATTERING DIRT ON AUTOMOBILE WINDSHIELDS IS SMALL, A VARIABLE AS ONE WOULD EXPECT, AVERAGE ONLY 4.8%, (4) GLARE SOURCES OF EXCEEDINGLY HIGH INTENSITIES WERE NOTED AND ALL CARS TESTED HAD CHROMIUM OF VARIOUS TYPES IN THE FIELD OF THE VIEW OF THE DRIVER, AND (5) DASH PANEL INSTRUMENT ILLUMINATION WAS GENERALLY MUCH TOO LOW IN THE DAYTIME TO PERMIT THE METERS TO BE SEEN AT A GLANCE. THIS IS IN ADDITION TO THE PROBLEM IN 4 ABOVE WHICH FUTHER INTERFERES WITH QUICK SEEING. /SRIS/

A new dark adaptometer.

A dark adaptometer that was designed for student-laboratory use is described and advocated for use in optometric practice because of its simplicity, accuracy, and low cost. Representative dark-adaptation results obtained from 2 naive and 2 sophisticated subjects are presented.

Daytime headlights and position on the highway

ABSTRACT Photographic recordings of the position of oncoming automobiles on the open highway in the daytime were made both with and without low beam headlights displayed on the camera car. A speed of 55 mph was maintained on the two‐lane U.S. Highway 37 north of Bloomington, Indiana. The positions of 1,127 vehicles were recorded. The oncoming cars occupied a narrower zone in their lane with fewer cars near the edge of the concrete as well as fewer near the center line when the camera car had its headlights on. It appears that the oncoming drivers were more alert when they faced approaching headlights in the daytime.

The effect of flares and triangular distress signals on highway traffic.

ABSTRACT The effect on traffic flow of distress signals placed near a “disabled” automobile beside a highway was studied. Both strontium nitrate flares (fusees), and reflectorized triangles were used. In the daytime there was little difference in traffic flow, whether signals were present or not. At night the flares were more effective in slowing traffic, and in addition they provided light for emergency repairs if needed.

Motorcycle helmet visibility and retro-reflectorization

ABSTRACT Twenty subjects made 1,100 judgments in the laboratory on the identifiability of a circle, triangle, square and rectangle of solid and open configurations at low luminance levels. The rectangle was the most identifiable with the triangle, square and circle following in order. The open configuration was almost as visible as the solid which had twice as much reflective sheeting in it. Six subjects made over 360 dynamic observations from an automobile. The various reflectorized shapes were detected at an average of 801 ± 21.4 ft while the normal white helmet was detected at 243 ± 143 feet. Recognition distance of the open triangle was the greatest, with the open circle, open square, open rectangle, total reflectorized helmet and no reflectorization following in that order.