Scottsdale staff defend flexible left‑turn timing and pilot detection tech; commissioners press safety tradeoffs

Scottsdale traffic engineers described the city’s Traffic Management Center (TMC) operations and defended a flexible, location‑by‑location approach to left‑turn phasing and signal clearance timing, while outlining pilot technologies to reduce conflicts for bicyclists and vehicles in “dilemma zones.”

“Scottsdale’s Traffic Management Center…is managing traffic at over 300 intersections and more than 14,000 streetlights across the city,” said Lehi Waal, senior manager and traffic engineer. Waal told the commission the TMC adjusts signal timing daily, uses about 226 miles of fiber and more than 200 video detection systems, and seeks to balance safety and throughput with context‑sensitive timing choices.

Waal explained three left‑turn operations — permissive, protected and…