Half-Diverging Diamond Interchanges open on South Mountain Freeway

Progress is being made on the South Mountain Freeway and on Monday, a two new "Half-Diverging Diamond Interchanges," commonly known as DDIs, opened.

The interchange first moves drivers through a traffic light, allowing one direction to move at a time before shifting traffic to the left to enter the freeway.

The lanes eliminate left-turn arrows, allowing drivers to merge left without cutting across traffic.

ADOT has opened the L-202 South Mountain Freeway interchanges at Desert Foothills Parkway and 17th Avenue. That means drivers are also using more freeway lanes in the area. However - speed limit is 40 mph as work zones are in place! (@ArizonaDOT)

According to the Arizona Department of Transportation, "DDIs are an innovative, proven solution to improve safety and mobility for motorists, cyclists and pedestrians."

ADOT VIDEO: Navigating a Half-Diverging Diamond Interchange

The two diverging diamond interchanges opened November 18 at the South Mountain Freeway Loop 202 at Desert Hills Parkway and at 17th Avenue.

"Starting Monday and continuing until next summer, there will be no access to and from the future freeway at 32nd Street, which will close south of Liberty Lane for interchange ramp construction. Interchanges at 24th Street and 40th Street are alternate routes. Access to Pecos Storage will be maintained throughout construction," stated ADOT officials.

There are two more diverging diamond interchanges planned in Arizona: one at the Interstate 17 and Happy Valley Road in 2020; the other is planned for Tucson.