CONTINUOUS FREEWAY ILLUMINATION

THE EFFECTIVENESS OF CONTINUOUS HIGHWAY ILLUMINATION, PARTICULARY ON FREEWAYS, IN REDUCING NIGHTTIME ACCIDENTS IS EVALUATED. THREE INDIRECT PROCEDURES USED WERE COMPARISON OF THE RATIO OF THE NUMBER OF DAY TO NIGHTTIME ACCIDENTS OF TWO ILLUMINATED FREEWAYS VERSUS THESE RATIOS ON NON- ILLUMINATED FREEWAYS /PARTIALLY ILLUMINATED AT INTERCHANGES/ , COMPARISON OF ILLUMINATED AND NONILLUMINATED FREEWAYS CONSIDERED TO BE SIMILAR IN DESIGN AND COMPARABLE AVERAGE DAILY TRAFFIC, AND COMPARIOSN OF THE ACCIDENTS OCCURRING BETWEEN 5 P.M. AND 7 P.M. IN JUNE, WHICH IS DAYLIGHT, VERSUS ACCIDENTS OCCURRING BETWEEN THE SAME HOURS IN DECEMBER, WHICH IS DARK, ON BOTH ILLUMINATED AND NONILLUMINATED FREEWAYS. ACCIDENT DATA ON THE FREEWAYS IN LOS ANGELES COUNTY FROM JAN, 1960 THROUGH JUNE 30, 1962 WERE UTILIZED. THE ILLUMINATED FREEWAYS STUDIED HAD AVERAGE MAINTAINED LEVELS OF ILLUMINATION RANGING FROM 0.20 FOOTCANDLES TO 0.35 FOOTCANDLES WHICH IS APPROXIMATELY 1/2 OF THE RECOMMENDED LEVEL OF ILLUMINATION BY AASHO. THE STUDY DID NOT SHOW CONCLUSIVELY THAT ILLUMINATION IS NOT BENEFICIAL OR THAT IT IS BENEFICIAL IN REDUCING NIGHT ACCIDENTS. THERE WAS SOME INDICATION THAT CONTINUOUS ILLUMINATION WAS REDUCING ACCIDENTS NOT INVOLVING FIXED OBJECTS AND WAS INCREASING THE FIXED OBJECT ACCIDENTS PRIMARILY DUE TO THE DISPROPORTIONATE FREQUENCY OF LIGHT POLE COLLISIONS. THE FREQUENCY OF LIGHT POLE COLLISONS WAS ATTRIBUTED TO THE DARK COLOR OF THE LIGHT POLES AND THEIR CLOSENESS TO THE PAVEMENT EDGE. PERHAPS THE MOST MEANINGFUL RESULTS OF THE STUDY WERE OBTAINED FROM THE COMPARISON OF THE NUMBER OF ACCIDENTS OCCURRING IN JUNE TO THOSE OCCURRING IN DECEMBER. FROM THIS INVESTIGATION IT WAS FOUND THAT DARKNESS IS A CAUSATIVE FACTOR AND THAT ARTIFICIAL ILLUMINATION DID NOT COMPLETELY COUNTERACT THE EFFECTS OF DARKNESS. DAY-NIGHT ACCIDENT RATIOS WERE FOUND TO BE APPROXIMATELY THE SAME FOR ILLUMINATED FREEWAYS AS FOR NONILLUMINATED FREEWAYS /PARTIALLY ILLUMINATED/. THE RATIO OF DAY TO NIGHT ACCIDENTS INCREASES WITH INCREASING TOTAL DAY TRAFFIC VOLUME EVEN THOUGH THE RATIO OF DAY TO NIGHT TRAVEL REMAINED APPROXIMATELY CONSTANT. THE ILLUMINATED FREEWAYS HAD NIGHTTIME AND DAYTIME ACCIDENT RATES WHICH WERE CONSIDERABLY HIGHER THAN THE RATES FOR THE SAME CATE- GORIES ON THE NONILLUMINATED FREEWAYS, BOTH IN THE INJURY PLUS FATAL ACCIDENT AND THE PROPERTY DAMAGE ACCIDENT ONLY CATEGORIES.

• Supplemental Notes:
  • Hpr, B-1-5, MAY65
• Corporate Authors:

  California Division of Highways

  Bridge Department
  Sacramento, CA  United States  05914
• Authors:
  • Johnson, R P
  • Tamburri, T N
• Publication Date: 1965-5

Subject/Index Terms

• TRT Terms: Alternatives analysis; Crashes; Daylight; Evaluation; Freeways; Night; Reduction (Chemistry); Street lighting
• Old TRIS Terms: Continuous highway illumination; Freeway lighting; Nonilluminated; Reduction
• Subject Areas: Highways; Safety and Human Factors;

Filing Info

• Accession Number: 00219650
• Record Type: Publication
• Source Agency: Bureau of Public Roads /US
• Files: TRIS
• Created Date: Oct 1 1994 12:00AM