ADOT official: Roundabouts safer, sensible
Multiple under construction here
The Yuma area now has traffic roundabouts under construction at two interchanges on Interstate 8, but the Arizona Department of Transportation announced last week it is planning to remove its oldest freeway roundabouts in north Phoenix.
But an ADOT spokesman says the state will continue to build the circular traffic calming devices when they make sense, as they do in Yuma at Giss Parkway and Araby Road (State Route 195).
The interchange at Happy Valley Road and Interstate 17 is being replaced by the state’s first “diverging diamond” interchange, which like a roundabout is intended to separate traffic going in opposite directions, and is gaining popularity in other parts of the country.
“We are planning to use
both diverging diamond interchanges and roundabouts because both are safer than the traditional interchanges. We’ll choose the right one based on the circumstances at each location,” Tom Herrmann of ADOT said.
Studies showed roundabouts are safer than a signalized intersection because they reduce or eliminate the possibility of a head-on or T-bone collision. ADOT, citing the Insurance Institute of Highway Safety, said they reduce fatal crashes by 90 percent and injury crashes by 75 percent, as well as a 30 to 50 percent increase in capacity.
However, the institute said most studies focus on single-lane roundabouts, and multiple-lane ones have seen smaller decreases in collisions or sometimes an increase, though they still tend to be less severe. The roundabouts at Giss and Araby will have two lanes.
Construction began Monday on the first of two roundabouts being built at Araby and Interstate 8 and is expected to continue to around the first week in November, Herrmann said.
It will then halt for the winter produce season because trucks use that intersection heavily, and start back up again in April, with work on both roundabouts expected to be done by November.
Current traffic restrictions include closures on the westbound freeway onramp and the eastbound freeway off-ramp on I-8, closure of Gila Ridge in both directions just south of Araby, and lane restrictions on Araby. Drivers can expect heavy traffic and are advised to use alternate routes.
The roundabouts will be located on the north and south sides of the freeway, with construction on the north one just getting underway. The $8 million project is being paid for by federal Highway Safety Improvement Funds.
“At Araby, the existence of a second intersection with Gila Ridge Road makes a roundabout the correct choice,” Herrmann said. “A roundabout can accommodate multiple entry points — the exit ramp from eastbound I-8 and Gila Ridge — that a diverging diamond cannot.”
The second roundabout interchange at I-8 and Giss Parkway has been going since March, and uses just one roundabout on the east side of the freeway to handle traffic entering the freeway, as well as cars going through on Giss.
The $1.8 million project should be done by October, Herrmann said. “At Giss Parkway, the roundabout is replacing a T intersection. A diverging diamond intersection does not work in that situation,” he said.
The highway ramps at Giss are still closed, but vehicles many drivers still face a can still get through learning curve whenever on Giss. one is installed in Arizona.
ADOT has an instructional Yuma County Engineer video on using roundabouts Roger Patterson said the online at: https:// county has built one roundabout, www.azdot.gov/media/atthesouthendofblog/posts/2016/06/22/ Avenue B approaching the driving-through-a-modernroundabout-doesn-t-haveto-be-confusing. commercial port of entry in eastern San Luis, but turned it over to the city
According to ADOT, after it was completed and the basic rules for using hasn’t been monitoring a roundabout are to slow how it functions. down when approaching John Savicky, senior the roundabout, look left engineer with the Yuma and yield to any oncoming County Department of Development traffic, and enter the Services, said roundabout cautiously at
he has worked overseas 15 to 25 mph.
In general, drivers making in countries where roundabouts a right turn should are common, but get into the right lane said resistance can build and use their turn signal, up when one is proposed those who want to turn left stateside, though there should enter the left lane, hasn’t been much vocal opposition and those who want to go in the Yuma area. straight should stay in the “We haven’t really matured same lane they started out with our use of a in. roundabout out here,” he
While many local drivers said. have some familiarity Still, he said the safety with the concept of traffic statistics show “it’s just a circles or roundabouts better way to regulate your through the small one further vehicle speeds and reduce west on Giss Parkway the severity of accidents, at Madison Avenue (in with the circulatory movement front of Yuma City Hall), of a roundabout.”