1994•Compendium of Technical Papers, 64th ITE Annual MeetingInstitute of Transportation Engineers (ITE)Requires access
THE PERMITTED LEAD-LAG LEFT-TURN DISPLAY
E J Seymour, J Green, John Black
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Abstract
Traffic engineers have used lead-lag left-turn phasing for many years to improve vehicular progression along roadways. These lead-lag displays may operate in either a protected-only mode or in a protected-permitted mode. Protected only operation allows the driver to turn on a left-turn arrow while all conflicting movements are stopped. Protected-permitted operation provides an additional green ball display to extend the driver's opportunity to turn while yielding to opposing through traffic. This article discusses permitted lead-lag (PLL) left turn displays as operated in Texas. It defines PLL operation, provides general guidelines regarding deployment, references pertinent research, and discusses ongoing efforts relative to compliance with national standards.