Tucson's dual left turns
In April 2024, Tucson made 10 intersections with two left-turn lanes arrow-only from 7 a.m. to 7 p.m. This page measures what happened, using every crash Tucson Police recorded at a signal from 2018 through 2026, and maps where the same design still yields on green.
What the data shows
Lane counts outside the 10 converted intersections come from OpenStreetMap, and their signal phasing hasn't been field-checked yet.
Where the dual lefts are
Size shows left-turn crashes from January 2018 to March 2024. Hover or tap an intersection for its numbers.
Left-turn crashes per vehicle
Before and after the 2024 change
If yielding from two lanes causes crashes, daytime left-turn crashes should fall at the 10 converted intersections and nowhere else. Night crashes there, when they still yield on green, should not.
Daytime left-turn crashes per intersection, by quarter
7 a.m. to 7 p.m. only. The shaded quarters are the 2024 rollout, left out of the before and after comparison.