SPEED PROFILES APPROACHING A TRAFFIC SIGNAL

THE OBJECTIVE WAS TO EXAMINE AND COMPARE THE SPEED PROFILES OF TRAFFIC APPROACHING A TRAFFIC SIGNAL UNDER SIX DIFFERENT SIGNAL DISPLAYS. DETECTOR LOOPS WERE INSTALLED ALONG ONE APPROACH TO A RURAL TRAFFIC SIGNAL INSTALLATION. DETECTOR ACTUATIONS, SIGNAL INDICATIONS, AND TIMING INFORMATION WERE RECORDED AT A REMOTE OBSERVATION POINT BY USING A 20-PEN OPERATION RECORDER. OBSERVATIONS WERE MADE OF LONE VEHICLES APPROACHING THE TRAFFIC SIGNAL LOCATION. THE SPEED PROFILES OBSERVED UNDER EACH SIGNAL DISPLAY WERE SUMMARIZED AND COMPARED WITH THE SPEED PROFILES UNDER THE OTHER SIGNAL DISPLAYS. DRIVERS AT THE STUDY LOATION ENTERED THE INTERSECTION MORE CAUTIOUSLY WITH A GREEN TRAFFIC SIGNAL INDICATION OR A FLASHING YELLOW INDICATION THAN THEY DID WITH NO SIGNAL INSTALLED. THEY DID NOT SPEED UP WHEN SIGNAL CONTROL WAS CHANGED FROM REGULAR STOP- AND-GO OPERATION TO FLASHING OPERATION. APPROACHING A RED SIGNAL INDICATION, DRIVERS DID NOT BEGIN TO SLOW DOWN UNTIL THEY WERE APPROXIMATELY 500 FT FROM THE SIGNAL. UNDER ALL OTHER SIGNAL DISPLAYS, DRIVERS GENERALLY MAINTAINED THEIR SPEED AS THEY APPROACHED THE SIGNAL LOCATION AND ENTERED THE INTERSECTION. /AUTHOR/