Shared left turn lanes are median treatments that have proven to increase traffic flow by as much as 70 percent and reduce accidents substantially.
Shared left turn lanes are in the center of roadways that have traffic flowing in both directions. They're between stoplights in urban environments and near T intersections of rural highways. They're marked with signs or on the pavement with two left turn arrows --- one for each direction of traffic.
Shared left turn lanes allow drivers making left turns into businesses or driveways or onto cross streets the opportunity to leave flowing traffic without disrupting it while awaiting opposing traffic to pass so the turn can be made safely. When used to enter traffic, the lanes provide a means of crossing oncoming traffic to a lane where the car can merge safely into traffic flow.
Shared left turn lanes take up less space than turn lanes for each direction of traffic. Because they do not disrupt traffic flow, they greatly reduce rear-end accidents caused by drivers who do not see left-turning cars paused in traffic. When used to merge into traffic, they allow drivers to cross just one or two lanes of traffic, going in one direction, rather than having to navigate both directions of traffic flow at once.
