As the Arizona Department of Transportation advances projects that will add capacity to Interstate 17 north of the Phoenix area, drivers can help improve safety and reduce delays today by avoiding speeding, aggressive driving, distraction from things like cellphones and other behaviors that lead to crashes.

The longest backups stemming from crashes occur most often on weekends, when many drivers take I-17 to and from Arizona’s high country.

“New lanes will play a role in improved safety, but driver behavior remains the key,” ADOT Director John Halikowski said. “The reality is that a reduction in speeding, sudden lane changes and impaired driving would reduce crashes, closures and frustrating traffic backups along this corridor.”

ADOT is conducting an environmental and design concept study scheduled for completion by summer 2019. Initial construction of a third southbound I-17 lane between Black Canyon City and Anthem is planned in 2020.

The Maricopa Association of Governments, the Phoenix area’s metropolitan planning organization, has committed $50 million in its Regional Transportation plan in 2019 and 2020 for design work and the start of construction of the third I-17 lane extending south from Black Canyon City.

ADOT’s statewide construction program includes more than $100 million starting in 2021 to build I-17 “flex lanes” between Black Canyon City and Sunset Point. Construction is expected to take two years.

Flex lanes will operate as a separate two-lane system next to the existing I-17 southbound lanes between Black Canyon City and Sunset Point. Separated by barrier wall, the flex lanes will carry vehicles in one direction depending on traffic needs.

These new lanes will provide flexibility and additional traffic capacity at times when I-17 traffic is heaviest in one direction, including northbound on a Friday or southbound on a Sunday. The flex lanes, with gates or movable barriers at each end, also will help keep traffic moving if a crash or other incident has occurred on the steep, winding section of I-17 north of Black Canyon City.

Driver behavior is the leading factor in crashes along I-17 in the Black Canyon City region. An ADOT analysis conducted for a recent safety project showed that “speed too fast for conditions” was cited by Arizona Department of Public Safety troopers in more than 40 percent of I-17 crashes in that area.