Due to a number of factors, and in order to protect a critical state investment, the Michigan Department of Transportation (MDOT) will not complete construction on northbound I-475 in Genesee County until approximately mid-summer 2020.
MDOT began the $44 million reconstruction and repair project along I-475 in August 2018, with the majority of construction occurring during the 2019 construction season, including the closure and detour of each direction of the interstate. The project includes sign improvements throughout the entire corridor; 3.5 mi. of reconstruction from Carpenter Road to Clio Road; drainage improvements; interchange reconfiguration at Saginaw Street; and resurfacing from Clio Road to the north junction of I-75/I-475.
The project timeline was initially impacted in 2018 by a labor dispute that slowed staging efforts, but significant impacts occurred by way of weather issues, with excessive precipitation in spring and summer 2019 and an early onset of winter in November.
"It's not uncommon to run into different issues throughout a major project like this one," said Steve Katenhus, Davison Transportation Service Center (TSC) manager. "In most cases you can adjust a schedule enough to make up for lost time but, in this case, the weather was working against us from the start of the project."
The I-475 project is part of a statewide effort to begin testing different pavement designs in real-world settings to determine if a new design standard is needed moving forward. Nearly all hot-mix asphalt (HMA) pavements are designed for a 20-year life span, which means, with proper preventive maintenance, MDOT can extend the life of those roads beyond 20 years before a road would need to be rebuilt.
In 2015, a legislative directive was issued that requires a more extensive look at longer-term pavement designs and how they respond in Michigan climates. I-475 in Flint was selected as a site to test the different pavement designs. Southbound I-475 features the standard 20-year pavement design, while northbound I-475 was designed with deeper layers of pavement and aggregate and is intended to last a minimum of 50 years with proper maintenance.
"We know these longer-term pavement designs are more expensive up front," said Keith Brown, Davison TSC construction engineer. "By testing these two designs side by side, we'll be able to determine if a higher up-front cost truly leads to less required maintenance over the life of the road. We may find that the initial investment doesn't pan out, as it's at minimum 35 percent more expensive but we really won't know until we try."
HMA paving under regular circumstances has weather limitations. Paving cannot be completed in temperatures lower than 35 degrees, with moisture also playing a role in limitations.
"We thought if we could get past the weather-related issues that occurred in the spring, we could possibly make up time," added Katenhus. "But that was followed by a rainy fall and then a very early winter storm. We delayed paving because we did not want to pave outside of our material specifications and contract language. There is far too much riding on this project when you consider the cost, time investment, and now also the research component involved with a 50-year pavement design."
To remain in compliance with seasonal limitations for HMA paving, as well as the minimum 35-degree temperature threshold, MDOT plans to begin paving on or after May 5, 2020. Northbound I-475 could reopen to traffic as early as July 1. Other construction items will remain ongoing through the winter to help reduce the workload remaining in the spring and help crews to reopen northbound I-475 to traffic as early as possible.