Carp River Bridge Upgrade Underway
The third phase of repaving on Mackinac Trail in Mackinac County has been completed, marking the end of all such work for the road. The reconstruction of about four miles was funded by American Recovery and Reinvestment Act (ARRA) money, which was awarded to the Hiawatha National Forest. Work is still underway to widen and strengthen the Carp River Bridge, where weakened concrete is being replaced now. Expected to be finished this fall, it also will be paid for by the national forest from ARRA funds.
The Hiawatha National Forest received more than $11.1 million in recovery act funds, which has been used for various projects throughout Mackinac, Alger, Delta, Schoolcraft, and Marquette counties. The Mackinac Trail project cost $1 million and this phase of Mackinac Trail work began in June.
Mackinac Trail was in rough shape previously, said Mackinac County Road Commissioner Tom Doty, with cracks and potholes found throughout. The road did not meet current National Highway Association standards, as travel lanes were only 10 feet wide. They have been expanded to 11 feet, meeting the standard. Shoulders along the road have been paved, as well, County Road Commission Manager Dirk Heckman said, benefiting bicyclists. No major work on the road is expected to be needed for the next 25 years.
Mackinac Trail has been redeveloped in three phases over several years. Most recently, the northernmost portion of the road in Mackinac County was reconstructed in 2007.
Mackinac Trail is both a county road and forest highway, national forest public affairs officer Janel Crooks said, and the service and road commission worked together to complete the reconstruction. Funding passed from the national forest to the road commission, which selected Rieth Riley Construction to handle the work.
With the recovery act funding the restructuring, the road commission was able to use its budget to focus on other road projects, instead, Mr. Doty explained.
Workers Hand-chipping Weakened Concrete From 90-year-old Bridge
Construction continues on the Carp River Bridge on Mackinac Trail.
The Northwest Design Group has performed a structural analysis of the 90-year-old bridge and is testing materials and overseeing construction. So far excavation has been conducted down to the bridge's arch, and the concrete is being tested for weaknesses. Workers tap the concrete and listen to the sounds produced to determine how strong the concrete is, said Gregg Ecker, a civil engineering technician with Northwest Design Group. Weakened concrete produces a dull thud, while strong concrete emits a sound like striking steel.
The weakened concrete is then hand-chipped from the bridge and replaced. It will also be waterproofed, and drains will be installed to relieve water pressure from behind and on top of the structure, said Amanda Porath, structural manager. The drains will route water back into the river.
To strengthen the bridge to handle heavy loads, expanded polystyrene foam blocks will be installed that are hardy enough to support the weight of an excavator. When the excavators begin filling the base of the bridge back in, the blocks will be added.
“That's something you'll never see when it's done,” Mr. Ecker said of the blocks.
The concrete road of the bridge will be replaced, and will be expanded from 22 feet to 27 feet. The bridge was originally so narrow some vehicles would have to yield for others to pass.
The approaching roads to the bridge will be paid for from ARRA money, while the bridge itself is funded through the Michigan Department of Transportation Local Bridge Program for roughly $900,000.
Other forest service recovery act-funded projects include Rock River Road aquatic organism passage culvert replacements for $295,000 in Alger County, and County Road 513 resurfacing and construction for $3.5 million in Delta County.