- Left turn arrow mis-interpreted to include U-turn restriction
Analysts recorded a number of false positives for U-turn restrictions based on left turn lane arrows that did not explicitly permit a U-turn as well. In general, left turn arrows should not be understood as an inferred U-turn restriction, unless some other reason for the restriction is present. For example, in this case below, Analysts flagged this maneuver as having a U-turn restriction. However, the U-turn takes place on a multi-lane road where there is a dedicated left turn lane and no other posted restriction in place, so this is a legal U-turn.
2. Turn channels not identified
Analysts do not always correctly identify turn channels, when they are present. When a turn channel is present, but not identified, some Analysts opted for dangerous turn or road markings instead.
Here are a couple of examples (one of which was used in the guidelines) where Analysts did not flag the turn channel restriction:
3. Non-lane space’ not identified as a road markings restriction
In the example below, a maneuver turns left before the end of a dedicated left turn lane.
Doing so also crosses a set of yellow lines that indicate a non-lane space that should not be crossed (red arrows).
4. Next Intersection’ Rule applied when dedicated turn lane is present
In this case, a U-turn occurs at an intersection with a dedicated turn lane and no other restriction in place. Analysts have flagged this as a U-turn restriction because a subsequent intersection also had a dedicated turn lane. In this case, however, the displayed U-turn is safe and legal to perform and should not be flagged as a turn restriction.
