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Unusual plan for I-75, University Pkwy. interchange

LAKEWOOD RANCH — State transportation officials say University Parkway traffic should one day cross Interstate 75 like the British — on the left side of the road.

A Florida Department of Transportation study is recommending a $217 million redesign of the interchange when I-75 is widened to 10 lanes. The design calls for briefly diverting each direction of University Parkway traffic to the left-hand side as they pass through the interchange.

It, and a similar design recommended for the I-75/Clark Road junction in Sarasota County, are the first “diverging diamond” interchanges to be proposed in Florida, FDOT spokeswoman Pamela Griffis said.

Those and the study’s other recommendations, which include building I-75’s new lanes in the median, are the subject of a public hearing Tuesday.

Under the diverging diamond design, both directions of University Parkway traffic would cross to the opposite side before reaching the I-75 overpass. Signals and signs would direct drivers at the crossovers.

Once on the left side, drivers could make unimpeded left turns onto the interstate or return to the right-hand side at another signalized crossover. Traffic also could turn right onto I-75 before reaching the initial crossovers.

Officials said the unusual design is safer because it eliminates left turns in front of oncoming traffic, a common cause of accidents at interchanges. The design also would save time by eliminating the need for left-turn signals and could reduce construction costs through better traffic flow, they said.

The design “provides significantly better levels of service in the design year without significantly higher costs or environmental impacts relative to the other alternatives considered,” the study said.

Those alternatives were adding lanes to the existing roads and ramps at an estimated cost of $215.2 million and splitting the northbound I-75 exit ramp into two, one for eastbound University Parkway and one for westbound, for an estimated $226 million.

Now only a handful of diverging diamond interchanges exist worldwide, mostly in France. None are in the United States, but several are in the works:

n Two are under construction, in American Fork, Utah and Kansas City, Mo.

n Missouri plans to build three others in Maryland Heights and Springfield.

n The design has been chosen for an interchange in Phoenix, Ore.

Officials in Kentucky, Maryland, New York and Ontario also are considering the idea, according to various news reports and government Web sites.

The study also recommended less-drastic changes for three other interchanges in Sarasota County when the highway is widened to 10 lanes. FDOT estimates it would cost nearly $1.29 billion to make those changes and widen I-75 between University Parkway and State Road 681, a distance of about 16 miles.

A separate but similar study estimated it would cost another $1.52 billion to widen I-75 and alter five interchanges in Manatee County.

The public will be able to voice their opinions and submit comments on the various recommendations during the hearing, which FDOT officials will incorporate into a final report, spokeswoman Lauren Hatchell said. That report then will be sent to the Federal Highway Administration for its approval.

FDOT officials said they do not know when, or whether, the project will be done. No money has been set aside in the next five years for design, right-of-way acquisition or construction.

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