Glossary

This page is meant to define and clarify the meanings of traffic control terms and lingo. Expand.......

Words and Meanings

LEADING / LAGGING ARROW

When a dedicated turn arrow is offered at a signal-controlled intersection, its operation will often be defined as either 'Leading' or 'Lagging'. Leading arrows happen at the beginning of the through green cycle, and generally end with a yellow arrow before the through green is finished. Lagging arrows often happen towards the end of the through green cycle, and usually have their yellow arrows tied with the through yellow, or simply rely on the through yellow entirely.

Signals that work together at either end of a bridge or overpass often feature lagging arrows to help clear out the short span of road between the two intersections, to help prevent cars getting stuck in line while trying to turn.

EXAMPLE

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Example example