17th Avenue and Desert Foothills Parkway Loop 202

The half-diverging diamond interchanges at the freeway’s intersections with 17th Avenue and Desert Foothills Parkway are the first in Arizona to utilize an engineering approach that will have vehicles driving on the left side of the ramps for a few feet.

With the full opening of the South Mountain Freeway reportedly only a month away, new developments and new challenges for motorists started this week.

And at least one – the closure of the intersection of the freeway and old Pecos Road with 32nd Street likely will create some havoc by forcing more traffic onto 40th Street.

The entire 6-mile Pecos segment opened this week in what the Arizona Department of Transportation called “a temporary configuration” with two lanes in each direction on the new freeway opened to traffic east of 17th Avenue.

The change puts an end to the meandering configuration of old Pecos Road that motorists had to follow for the last two years while the freeway’s infrastructure was being built.

“Drivers should be aware that the area will continue to be a work zone with a speed limit of 40 mph,” ADOT said.

But among the new challenges is the opening of an interchange system that’s new to Arizona but in use in a number of other states – a ”half-diverging diamond interchange.”

Those interchanges at Desert Foothills Parkway and 17th Avenue may prove some getting used to since drivers entering and exiting the freeway will be driving on the left side of the pavement.

In a diverging diamond interchange, traffic follows signs and lane markings to move to the left side of the road and enter on-ramps directly without having to turn across oncoming lanes.

The two interchanges are only “half-diamonds” because there are no roads south of the freeway.

The interchanges “accommodate pedestrians and cyclists traveling to and from a multi-use path that is expected to open next summer,” said ADOT in a release, urging motorists to see how the interchanges work at azdot.gov/SMFDDI.

Motorists who don’t necessarily use Pecos Road or the freeway also will be encountering a new challenge this week.

Until at least next summer, 32nd Street will be closed south of Liberty Lane, although access will be maintained to the popular Pecos Storage facility that is south of the freeway path.

With 32nd Street a popular route for people heading to the area housing Desert Vista High, Akimel A-al Middle School and Esperanza Elementary, more traffic likely will be using 40th Street.

A large and popular park-and-ride lot is located at the intersection of 40th and the freeway.

The work on the 32nd Street interchange was only approved this year by ADOT, which had not included it in the original freeway design because, it said, a citizens advisory committee told the highway agency they opposed it.

But the tide turned in favor of the interchange and ADOT said it received overwhelming support for it through emails and an online poll.

The lack of an interchange at that spot had sparked considerable concern two years ago after former legislator Rob Robson, then of Chandler, noted it left no alternative evacuation route for the schools near Liberty Lane in case of a major emergency.

Lawmakers then pressured ADOT into agreeing to construct a road that would be open only to emergency vehicles. The need for that thoroughfare no longer exists.

The 22-mile freeway, which voters first approved in 1985, began becoming a reality after the Gila River Indian Community and the Ahwatukee-based Protect Arizona’s Children and Resources lost a federal court case aimed at stopping it in its tracks.

At a cost of $1.7 billion, the freeway – which will connect the Chandler and W. 59th Street interchanges on I-10 – is the most expensive highway project ever undertaken by the state.

The projected number of vehicles expected to use the freeway on any given day ranges between 120,000 and 140,000 – including at least 60,000 trucks, mostly big rigs.

Multiple sources have told AFN that the freeway will open Dec. 20, although ADOT has not given any date except to say it will be open by the end of this year.

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