In most of our villages, and in all larger metropolitan areas, some or many intersections are controlled by signal lights with left turn arrows during the phases of the particular signal. In Franklin County, left turn signals are most often encountered on state highways. In most cases, where these turn arrows exist, they are normally at the beginning of a particular phase of a traffic signal. For instance, in Malone, at the Finney Blvd/W. Main St. intersection, left turn green arrows activate for left turning vehicles before straight through traffic gets a green light. Some advantages with the turn arrow at the beginning include higher intersection capacity on restricted width roadways, less conflicts between left-turn and opposing through vehicles and less traffic congestion by clearing the left-turning vehicles through the intersection first.

But there are disadvantages as well. Vehicles often continue turning left after the green arrow extinguishes, pre-empting the right of way from opposing vehicles when oncoming traffic gets the green light.

Occasionally an intersection has a green left turn arrow at the end of the signal phase, as is the case for westbound traffic on W. Main St (US Route 11) in Malone at the intersection of Harrison Place. When the green arrow comes on near the end of the green phase, both directions of straight through traffic get a green light at the same time, which approximates the normal driver expectancy. Also, less time is needed for the green arrow since left turns can filter through the opposing gaps in oncoming traffic.

At the W. Main St./Harrison intersection, the main reason for the arrow at the end of the phase is because there is no dedicated left turn lane for westbound traffic. But a disadvantage of an intersection where the green arrow is at the end of the phase is if the first or second vehicle wants to turn left and can’t because of oncoming traffic, it forces traffic behind this vehicle to wait until the driver is able to complete his/her turn, as is the case at W. Main and Harrison. In some cases this could be until the signal turns red again. However, if any vehicle or series of vehicles in the left westbound lane of Main St are detected beyond a pre-programmed length of time, the left turn arrow for turning from W. Main onto Harrison will activate.

Programming traffic signal lights is a complex and detailed job. In spite of drivers thinking they know best, it’s prudent that programming traffic signals is left to the experts.

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Johnson Newspapers 7.1

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