New speed-feedback message signs deployed on mountainous section of Arizona’s I-17


The Arizona Department of Transportation (ADOT) has activated six new electronic signs to send safety messages to drivers about dangerous speeding on the steep, winding stretch of Interstate 17 in the Black Canyon City area north of Phoenix.

ADOT’s new speed-feedback signs tell drivers they are traveling over the speed limit, and feature the posted speed limit and a digital screen, displaying vehicle speeds to I-17 users in areas between Black Canyon City and the Sunset Point Rest Area. The signs, which primarily track traffic in the left (outside) lane, display vehicle speeds starting 10mph (16km/h) below the speed limit, as well as ‘too fast’ or ‘slow down’ messages focused on those who are driving above the limit. ADOT installed the permanent speed feedback signs earlier this year as part of a US$1.1m I-17 safety project between New River and Camp Verde, and they were activated in late November.

A study conducted in advance of the I-17 safety project found that Department of Public Safety troopers cited ‘speed too fast for conditions’, as the leading driver violation in more than 40% of I-17 crashes that occurred in the Black Canyon City area between 2011 and 2015. The new speed-feedback signs serve as a safety tool in an area where crashes and other incidents, including disabled vehicles, can cause closures and lengthy delays along I-17’s winding gradient. Other features of ADOT’s I-17 safety project north of Phoenix include four new digital message boards installed earlier this year to alert drivers to highway conditions and provide safety messages. Crews also have posted additional signs to advise drivers about highway curves. Speed limits along I-17 generally range from 65-75mph (105-121km/h), with lower advisory speeds on signs in some areas with curves.

ADOT also is studying possible improvements to the I-17 corridor between Anthem Way and State Route 69 at Cordes Junction, before finalizing plans for adding new lanes and other safety enhancements. With funding from the Maricopa Association of Governments, which serves as the metropolitan planning organization for the Phoenix area, projects to add new I-17 lanes in areas between Anthem and Black Canyon City are now scheduled for construction in the years 2021-22. The concept of building ‘Demand/Reversible Lanes’ between Black Canyon City and Sunset Point, for use as needed by the busiest direction of travel or in the event of a closure, is just one idea being considered for that mountainous section of I-17. Funding for improvements in that area has not yet been identified.

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Tom has edited Traffic Technology International (TTi) magazine and its Traffic Technology Today website since May 2014. During his time at the title, he has interviewed some of the top transportation chiefs at public agencies around the world as well as CEOs of leading multinationals and ground-breaking start-ups. Tom's earlier career saw him working on some the UK's leading consumer magazine titles. He has a law degree from the London School of Economics (LSE).