U-turns are generally permitted in Missouri except where prohibited by state, local municipal law, or posted signage. U-turns are specifically prohibited at intersections controlled by a traffic signal. See MO Statute 304.341(2) for complete legal restrictions.
For Waze routing, u-turns should only be enabled where they provide the potential for improved routing, which includes recovering from missed turns. A common example is a median-divided primary street that has homes/businesses with their driveways/entrances directly on it, where reaching them would otherwise require lengthy, multi-turn deviations through side roads in order to end up on the correct side of the median.
The u-turn must also meet the following criteria:
- The u-turn is explicitly allowed by signage or is otherwise legal and safe.
- The turn can be completed in one continuous movement. This is not a specific legal requirement in Missouri, however would be good practice for safer navigation.
Note that when editing, a functional u-turn can arise from more than just the u-turn flag on a road segment, such as with these common scenarios:
- Divided roads with box and partial-box intersections where the median segment is 15 m (49 feet) or longer.
- Divided roads with explicitly-mapped inside turn lanes unless the turn arrow in the u-turn direction is disabled.