Urban mobility problems demand clarity. Intersections remain the most common sites for crashes, congestion, and violations.

Have you ever wondered how traffic lights know when to give you a signal? Reader Nick Shepard asked Bee Curious, a community-driven series in which The Sacramento Bee’s service journalism team answers ...

Every time we stop at a red light, wait patiently for green, or slow down on yellow, we’re participating in a system that quietly keeps billions of people safe. But have you ever wondered who invented ...