Why Concrete Outlasts Asphalt for Michigan Roads
When a Michigan highway gets rebuilt in concrete instead of asphalt, the decision rarely comes down to a soundbite about which material simply lasts longer. It comes down to a design methodology built specifically to model how a slab of concrete will behave under millions of truck axle loads, decades of freeze and thaw cycles, and the specific soil and climate conditions of that stretch of road. That process, not a marketing claim, is why concrete pavement performs the way it does on Michigan's state routes and interstates.
This page walks through that process directly, using Why Concrete as its starting point. Readers newer to concrete paving fundamentals may want that background first. This page covers the design method MDOT uses for concrete roadways, the standards it produces, and a real Michigan highway project built to them.
Road-Class Concrete Is a Different Engineering Discipline
A parking lot or a driveway is not designed the same way a state highway is. MDOT's method for designing new and reconstructed pavement, AASHTOWare Pavement ME Design, explicitly excludes parking lot concrete and carpool lots, which are engineered instead with an older, simpler method. That exclusion is the clearest sign of how different the two disciplines are: road-class concrete goes through a modeling-based design process built around a specific route's traffic and climate, while a parking lot generally does not need that level of engineering to do its job.
What Mechanistic-Empirical Design Actually Does
From an Older Empirical Method to Pavement ME Design
For years, pavement design leaned on AASHTO's older empirical method, a set of formulas built from historical pavement performance data rather than a specific project's own conditions. MDOT has been implementing AASHTO's Pavement ME Design software, a mechanistic-empirical approach that models a project's specific traffic loads, local climate data, and actual mix materials directly, rather than applying a generalized formula. For concrete roadways, this method is used to design Jointed Plain Concrete Pavement, commonly shortened to JPCP, producing a design built around what a particular stretch of road will actually face rather than a statewide average.
Readers wanting the underlying design guidance behind this approach can review MDOT's mechanistic-empirical design guidance directly, including the User Guide referenced throughout this page.
A Real Michigan Example: US-31 Design
Project Design Specifications
Thermal Stress and Michigan's Climate
That same modeling also accounts for thermal stress. MDOT's design software includes a permanent curl and warp temperature input, which reflects how a concrete slab expands and contracts with the seasons using the same localized climate data referenced above. Michigan's freeze and thaw conditions are built into the engineering itself, not treated as a side note.
Thickness and Joint Standards for Michigan Roads
MDOT's minimum pavement thickness standards set a starting point for any JPCP road project. Standard JPCP must be at least 8 inches thick on non-freeway roads and 9 inches on freeways, with widened slabs requiring a 9.5 inch minimum.
Joint spacing and dowel bar diameter are not left to individual judgment either. Both are standardized and scale with slab thickness under MDOT Standard Plan R-43 for joints and R-40 for dowels, which is part of why a specific project's design, like the 14 foot joint spacing and 1.25 inch dowel bars used on US-31, can be checked directly against a known standard rather than taken on faith.
Frequently Asked Questions
What is Jointed Plain Concrete Pavement, and how does MDOT use it on Michigan highways?
Jointed Plain Concrete Pavement is a rigid pavement design that uses regularly spaced joints, rather than reinforcing steel, to control where a concrete road slab cracks as it expands and contracts. MDOT uses JPCP as its standard concrete pavement type for Michigan's reconstructed and new highway projects, sized and detailed through the mechanistic-empirical design process described above.
Why doesn't MDOT use the same design method for parking lots in Michigan?
MDOT's mechanistic-empirical design method is built around the traffic loads, climate stress, and design life expected on a Michigan state route or interstate, which is a different engineering problem than a parking lot presents. Parking lots and carpool lots are explicitly excluded from that standard and are designed with an older, simpler method instead.
How does Michigan's climate factor into concrete highway design?
MDOT's pavement design software uses localized climate station data, like the Holland, Michigan station used on the US-31 project, along with a permanent curl and warp temperature input that models thermal stress in the slab. Michigan's freeze and thaw conditions are built into the engineering itself rather than treated as a side note.
How thick does a concrete highway need to be in Michigan?
Per MDOT's minimum standards, Jointed Plain Concrete Pavement must be at least 8 inches thick on non-freeway roads in Michigan and 9 inches on freeways, with widened slabs requiring 9.5 inches. Actual thickness on a given project, like the 10 inch design used on US-31, can run higher depending on the traffic and climate inputs for that specific route.
Does MDOT's mechanistic-empirical design method apply to local and municipal roads in Michigan, or only state highways?
MDOT's mechanistic-empirical design process, as described on this page, is used for state trunklines and interstates under MDOT's own jurisdiction. Municipal engineers managing a city or county road project in Michigan should confirm which design method and thickness standards actually apply to their agency, since local requirements can differ from MDOT's own specifications.
Bring MDOT-Grade Standards to Your Next Michigan Project
Municipal engineers and DOT decision-makers working on a Michigan road project do not need to start from scratch on concrete pavement design. MDOT's own standards, backed by the mechanistic-empirical process covered here, give a defined starting point for slab thickness, joint spacing, and climate-specific design inputs. MCA's technical resource library, member contractor directory, and MCA team are available for project-specific questions.
Readers looking for the broader concrete-versus-asphalt comparison for general property or commercial projects, rather than the DOT-specific standards covered here, can find that comparison on the association's longevity comparison page.
Michigan's highways are engineered, not just poured, to survive the state's freeze and thaw climate and years of heavy truck traffic, and that distinction matters for anyone deciding how a road project should be built. Michigan Concrete Association exists to help municipal engineers and DOT decision-makers understand exactly how that design methodology holds up before the first slab goes down.
