Diverging Diamond could be coming to Tucson interchange

TUCSON, Ariz. - ADOT is proposing an interchange concept for Houghton Road at I-10 that is so new, there is only one other in Arizona.

It's called a Diverging Diamond or DDI, and it will allow both directions of Houghton to cross over the opposite side of the bridge, moving over the top of I-10.

According to ADOT's Tom Herrmann, "When you pull up to the traffic signal you'll actually cross over to to the left side of the roadway. Sounds a little scary, but it's actually a safer way to get through the interchange. As soon as you get through the interchange, you'll go back to the right side of the road where you belong." Herrmann says it is a safe, quick and efficient process.

The DDI is being proposed because of the expected 2 to 3 fold increase in Houghton traffic over the next 10 to 15 years, is cheaper to build and drivers are less likely to enter I-10 in the wrong direction.

ADOT admits that it'll take Tucson travelers a little while to get used to the idea of crossing over I-10, while appearing to be travelling the wrong way.

"We've actually seen studies from the Federal Highway Administration that 97% of drivers feel safer when using a diverging diamond interchange, so we're very confident this is a safe design," says the ADOT Spokesman.

There will be an open house to introduce the DDI Thursday at Empire High School, from 5:30 to 8 P.M.. It will be in the dining auditorium.

Those who are unable to attend can provide comments or ask questions by either calling 855-712-8530, sending an email or sending comments and questions to ADOT Communication, 1655 W. Jackson Street, MD 126F, Phoenix, Ariz.,  85007.

ADOT has already begun the design process for the project. Construction of the DDI is scheduled to begin in 2020.

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