Dedicated turn lanes allow vehicles to slow down to turn without effecting the flow of through traffic. This reduces the risk of rear-end crashes.

Unsignalised intersections turn lanes also provide a safe place for turning drivers to wait for a gap in the opposing traffic. This reduces the risk of a crash between the turning vehicle and opposing through vehicles.

Cross-traffic turn lanes sheltered by a median provide better separation from the opposing traffic stream but turn lanes can be also created with line marking. Sometimes the road can be made wider to fit the turn lane by sealing the shoulder or by taking parking space. Sometimes road carriageway widening is required.

Turn lanes are often beneficial for existing road junctions, even if the layout is sub-standard and narrower lane widths are used. They are also desirable where intersections are located on bends where visibility is constrained.