VIDEO: MoDOT Installing Flashing Yellow Left Turn Signals on Route 100 in Washington

The Missouri Department of Transportation will install flashing yellow left-turn signals on four intersections along Route 100 between South Point Road and Washington Heights in Franklin County between July 27 and August 3, weather permitting. MoDOT will work on one intersection per day starting on the west end of Route 100 at Washington Heights.

The flashing yellow left-turn signals will be installed on Route 100 at Washington Heights, International/Rabbit Trail, Brookview/Vernaci and South Point Road. Current signs at the intersections will be replaced with a new sign "Left Turn Yield on Flashing Arrow."

These left turn signals use a flashing yellow arrow, pointed left, instead of a round green signal, to indicate that drivers may make a yielding left turn. Since drivers tend to associate "green" with "go," and "yellow" with "caution," studies have shown that drivers more easily understand the flashing yellow arrow. These new signals also use red arrows instead of the traditional round red signals.

These signals let engineers adjust the signals based on traffic patterns. Most of the time, drivers will be able to make a yielding left, increasing their opportunities to make left turns safely. During periods of heavier traffic, however, drivers may only have a green arrow, allowing them to make a protected left turn.

MoDOT has used these signals since 2006 on Olive Boulevard in Creve Coeur at the intersections of Mason, Ross/Questover, and Barnes West/Heritage Place. They have also been installed recently in O'Fallon on Route K near Interstate 70, and in Florissant and Hazelwood along Lindbergh Boulevard. These signals are in use at approximately 50 locations statewide.