Northbound I-75 is likely to be closed for about seven months, and possibly longer, when the Ohio Department of Transportation detours traffic later this spring because of soil problems interfering with replacing two bridges over ramps at the I-280 junction in North Toledo.

The detour will not be long — only about a mile — and will not require freeway motorists to use city streets except for one short piece of Central Avenue that will be closed to other traffic, according to plans ODOT will discuss during a news conference today to announce its Toledo-area construction schedule for 2016.

But temporary ramps to be built from I-280 to Central as part of the detour route will have sharp curves that will restrict traffic speed, and that’s likely to cause major delays during peak hours, Todd Audet, ODOT’s district deputy director in Bowling Green, said Monday.

“It’s going to be slow, but safe,” Mr. Audet said. “You can only push so much volume through the section where traffic has to slow down.”

About 47,000 cars and trucks use northbound I-75 through the I-280 junction on an average day. Southbound I-75 will not be affected.

The northbound closing, likely to start in early June, will effectively add an exclamation point to the north end of a 50-mile zone between Findlay and Toledo where I-75 is being rebuilt, including about six miles through and near downtown Toledo.

The detour is one of two major freeway shutdowns ODOT is planning in Toledo later this construction season.

Perrysburg issue

Also planned is a 120-day closing of northbound I-75’s ramps at I-475/​U.S. 23 in Perrysburg so they can be overhauled. That's scheduled to start in late spring or early summer, depending on how fast previous construction phases there are finished.

Toledo’s freeway system in general has been besieged by orange barrels, with I-475/​U.S. 23 also in the midst of two projects to widen bridges near Airport Highway and rebuild the Central Avenue interchange in Sylvania Township.

The I-75 problem will also add millions of dollars to the cost of ODOT’s $62.6 million contract with Kokosing Construction Co. to widen the section between Lagrange Street and I-280.

But Mr. Audet said that by rebuilding the bridges without any traffic using them, delay to that contract’s 2017 completion can be avoided.

Ramps needed

A significant part of that extra cost will be building the temporary ramps at I-280 and Central, which Mr. Audet said state officials found preferable to using the existing Greenbelt Parkway interchange.

That decision is still subject to an “environmental justice” review now under way, Mr. Audet said. If the proposal goes forward, the ramps’ expedited construction is likely to start in early May and take about a month, he said.

Mr. Audet said the soil problems will be explained in greater detail during the news conference today, but their effect is to change the design of retaining walls Kokosing must build near the bridges over the I-280 ramps in a way that precludes maintaining two full-width lanes for northbound I-75 during construction.

Officials considered reducing the lanes to 10 feet wide, he said, but disliked that idea for safety reasons, especially because of the chance that winter weather will arrive before full width can be restored.

The detour “may extend beyond Thanksgiving,” the ODOT deputy director said. “If it goes into winter, our goal is to keep construction [overall] from going another year.”

The other detour option officials considered was using the Greenbelt ramps, but that would lengthen the detour and require closing Greenbelt to traffic and blocking several bicycle/​pedestrian paths that converge in that area, Mr. Audet said.

The detour plan calls for Central to be closed to vehicular traffic between Galena and E streets, but a sidewalk will be maintained on the south side of Central across I-280 for pedestrians and cyclists. It will be separated from the detouring traffic by concrete barrier and chain-link fences, Mr. Audet said.

All northbound I-75 traffic would be forced to exit at the ramp to southbound I-280, which would be restriped to provide two lanes instead of its normal one.

Motorists wishing to return to northbound I-75 would then be directed through the temporary loop at Central to reach northbound I-280, which leads back to I-75. The entire loop will have two lanes, but the curves leading to and from the bridge will probably be posted with 25-mph speed limits, Mr. Audet said.

Northbound I-280 will be reduced from three lanes to two at Greenbelt to handle the addition of two lanes coming in from the Central loop. North of Central it will have four lanes until the left lane peels away as the exit to southbound I-75.

The ramp from southbound I-75 to southbound I-280, meanwhile, will be reduced to one lane from its normal two to avoid a merging problem with the extra lane coming off northbound I-75.

ODOT plans to keep all ramps open at the Manhattan Boulevard interchange even though traffic entering southbound I-280 from Manhattan will have to contend with vehicles using the I-75 detour.

Traffic that normally uses Central to reach Galena will be detoured via Lagrange Street and the Greenbelt.

Along with the detour using the Central loop, ODOT plans to step up efforts to urge through traffic to use State Rt. 795 and I-280 as an I-75 alternative while the bridges are closed, Mr. Audet said.

Contact David Patch at: dpatch@theblade.com or 419-724-6094.

First Published March 29, 2016, 4:00 a.m.