French connection may control traffic flow

5/2/2005

FINDLAY - Driving on the left, common in England, Japan, and parts of the Caribbean, may soon take root on a short section of U.S. 224 in a pioneering effort to reduce traffic congestion at minimal cost.

The Ohio Department of Transportation is studying the possibility for reversing the normal flow of traffic on U.S. 224 between the interchange-ramp intersections at I-75 west of downtown Findlay. Motorists would cross over to the left at the first ramp intersection in each direction, then cross back over to the right on the other side.

The flip-flop, which would be governed by traffic lights so opposing traffic would not move simultaneously, would allow traffic turning left from U.S. 224 onto I-75 entrances to move continuously in both directions, and that's the key to the proposal.

Such a design, called a "diverging diamond interchange," has never been used in the United States, said Kirk Slusher, the planning administrator at ODOT's district office in Lima. The proposal is based on a traffic pattern at a highway junction in Versailles, France, he said.

"Our congestion analysis shows that it improves the level of service dramatically," Mr. Slusher said.

About 20,000 vehicles use the four-lane U.S. 224 bridge over I-75, but land west of the interchange is booming with development, including several projects under way and a Wal-Mart on the drawing board for a site southwest of the junction, Mr. Slusher said.

The traditional solution

would be to widen the bridge to six lanes, adding dual left-turn lanes in the center, Mr. Slusher said.

But that would be a multi-million dollar project, and state inspectors have determined that it will be at least five years, if not 10, before the bridge would otherwise come due for overhaul.

Furthermore, the ODOT planner said, a traditional design would not handle the volume of traffic expected on the day it would be finished, whereas a computer model of the diverging diamond indicates it is adequate for at least 20 years of growth.

State officials presented the concept to Findlay and Hancock County leaders last month. While a decision whether to use it won't be made until late summer, Mr. Slusher said, "Everybody is in favor of least investigating it."

Ed Ingold, chairman of the Hancock County commissioners, said his only hesitance about the project is whether a tax-increment financing program, which uses revenue from a special taxing district to pay for public works associated with new development, will provide enough money to pay for it.

"It's intriguing. It'll be an interesting project if they go through with it," Mr. Ingold said. "They showed us a simulated view of it, and it appeared to work."

"I think it's a great idea," Findlay Mayor Tony Iriti said.

"It's amazing to me that this has never been done before," he said. "We'll be written up in all those [engineering trade] magazines nobody wants to read."

But ODOT's staff reads them.

Mr. Slusher said state engineers were inspired by a trade-magazine report on the French interchange.

The weaving concept relies on traffic islands to guide motorists from one side of the roadway over to the other at each crossover point, and includes a concrete divider to separate traffic in between them. Mr. Slusher said planners are looking at the potential to use small lights embedded in the pavement to reinforce the crossover pattern for motorists.

Another consideration is installing surveillance cameras to help identify the causes of accidents, with an eye toward determining whether the diverging diamond pattern confuses drivers. But Mr. Slusher said the projected accident rate is half that of a normal interchange - the traffic maneuver most prone to accidents is a left turn across oncoming traffic, and the weaving proposal eliminates those.

Mr. Ingold said he doesn't think Hancock County drivers would need long to adjust to the unfamiliar layout.

"Once people get used to it, it won't be a problem," he said.

Contact David Patch at:

dpatch@theblade.com

or 419-724-6094.