MANSFIELD — A proposed $800,000 tunnel beneath a four-lane section of Trimble Road would eliminate a significant potential safety hazard along a planned bike trail connector project.

City of Mansfield engineer Bob Bianchi said Tuesday the 100-foot long underground passage would eliminate the possibility of vehicles colliding with bicycles and/or pedestrians on a connector that will link the B&O Bike Trail and the sidewalk on the east side of Trimble Road.

“This crossing is critical to the bike trail network and we wanted to make sure it’s as safe as possible,” Bianchi said. “This is absolutely the safest alternative we have.”

The engineer will seek various forms of funding for the tunnel, which would become a part of a previously-approved $1.75 million connector project planned to built in 2025.

That project, approved in 2022 and under design, is being funded by $500,000 in American Rescue Plan Act money from the City of Mansfield, $500,000 in ARPA from Richland County, $150,000 in state capital funds and $600,000 through RCRPC.

When completed, the connector will be a 1.25-mile, 10-foot wide, multi-use path to the 18.4-mile bike trail that runs from Mansfield to Butler.

For the tunnel, Bianchi said he planned to request another $250,00 from the city’s ARPA funds, $200,000 from county commissioners (likely in ARPA) and $200,000 from the city’s permissive sales tax. He said he would also  submit a $200,000 grant application to the Richland County Foundation.

Those requests would likely be made in March and April, he said.

Bianchi said the Trimble Road crossing has been a safety concern since officials hiked the proposed connector trail four months ago. He said he has already had a conversation with county Commissioner Darrell Banks, who expressed his safety concerns.

Initially, the plan was to perhaps use the same kind of pedestrian-initiated strobe flashers used on Diamond Street in downtown Mansfield near the Richland County Administration Building.

“That kind of signal doesn’t work as well on a street as wide as Trimble,” Bianchi said. “It just wouldn’t be effective.”

The engineer said a full traffic signal light was also considered.

“That intersection is not warranted for a signal due to the (amount) of traffic,” he said. “Even then, we would have concerns about pedestrians crossing with cars traveling 35 miles an hour.”

A bridge over Trimble Road would not work due to the length of the ramps necessary to make it ADA-compliant, he said. “It would be way too expensive and it just wouldn’t work in that location.”

At a Mansfield Rising meeting, Bianchi said he spoke with Maura Teynor, chief advancement officer for the Richland County Foundation.

“She said, ‘What about a tunnel?’ At first glance, I thought she was joking,” Bianchi said. “Later that night, I began asking myself if it was possible.

“We looked at the utilities in the area. We don’t have a sanitary sewer line there and we will never need one. We looked at the topography and the west right-of-way looks perfect for a tunnel to protrude outside the hill,” Bianchi said.

“I said, ‘My goodness, this could actually work. It could be very feasible.'”

Bianchi and his team put together a preliminary drawing/study to examine how the tunnel would work.

Plans call for the tunnel to be 14-feet wide and about 10-feet high, running about 15 feet below the surface of Trimble Road.

“We are looking at lighting the tunnel, putting in an emergency call device and potentially putting in a camera — all for safety reasons,” he said.

The tunnel would pass beneath Trimble Road and then curve back around to connect to the concrete trail/sidewalk. Additional grading would need to be done on the east side of the road to accommodate the tunnel structure, Bianchi said.

“We will need to acquire a little bit of property for the project. I have spoken to the property owners,” he said.

“We want to be cognizant of the fact this is prime real estate. We want the alignment of the trail to be conducive to future development.”