Phoenix drivers should be aware that the next round of State Route 51 (Piestewa Freeway) ramp meter adjustments kicks off this week.

This aims to improve the flow of morning rush-hour traffic as part of an Arizona Department of Transportation program that began last year with the freeway’s northbound on-ramps.

Instead of being programmed with predetermined red-light intervals, the new system will use real-time data from traffic-flow sensors embedded within the freeway’s pavement. This will adjust the signal timing, and when traffic slows down, the meters may hold vehicles for a few additional seconds to help relieve congestion.

This change affects southbound SR 51 on-ramp meters from Greenway to Thomas roads in Phoenix. Just like the northbound State Route 51 ramp meters during the afternoon rush hour, the southbound meters may switch off earlier in the morning based on traffic flow.

This project aims to reduce the percentage of time metro-area freeways are congested, as outlined in Governor Doug Ducey’s Arizona Management System. These ramp meters have been used for many years across the country, especially in the crowded, congested freeway and highway system of the valley. These upgrades will lead to enhanced traffic flow and safety by limiting the number of vehicles entering freeways at any given time, and these changes will pave the way for new technology and innovation.

This upgrade project is being closely monitored by the Arizona Department of Transportation and the city of Phoenix, and updates will be provided on any impacts to traffic on local streets intersecting with SR 51. Visit the official Department of Transportation website for more information.