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Copyright
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(Copyright © 1977, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing) |
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Abstract
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The impact of various traffic control devices such as traffic signals, two-way and four-way stops are discussed. Manual vehicle classification, inter-section controls and automatic traffic recorder counts were conducted.
RESULTS indicated that for both study areas (south Philadelphia and north central Philadelphia), traffic volumes remained relatively static between 1960 and 1973. Accident records for 1969 to 1976 were analyzed to determine accident severity (property damage, occupant injury, pedestrian fatality), type (right angle, rear end, fixed object, side-swipe, pedestrian), and time of day (daylight, darkness). A before and after analysis was conducted at all locations where the control mode changed during the study period.
RESULTS of the two-way to four-way stop control indicated that accidents decreased by 87 percent and personal injuries decreased by 92 percent. The four-way stop program has proved successful in reducing the number of yearly new traffic signal installations by 65 percent. There remains acritical need for an objective examination of the wider-range effects of the citywide traffic control changes that averaged 5/week over the past 9 years. |