Editor’s note: This article is adapted from a version published Oct. 28, 2026, by the Center for Transportation Studies at the University of Minnesota.
An expanse of freshly paved asphalt is a dream to drive on — but it doesn’t last. Inevitably, thermal contraction and Minnesota’s extreme freeze-thaw cycles cause the road to crack. To combat problematic cracking, many Minnesota cities and counties preemptively “saw and seal” roads by sawing neat, evenly spaced cuts into new asphalt and filling them with sealant. This forces the pavement to expand and contract at predictable spots, keeping the surface smooth and making future repairs simpler.
To help local transportation agencies determine how saw-and-seal strategies could yield the highest road quality for the lowest life-cycle cost, a new study led by UMN civil, environmental, and geo- engineering professor and CTS scholar Mihai Marasteanu evaluated two primary crack-prevention approaches. Funded by the Minnesota Local Road Research Board, the study compared standard, lower-cost asphalt paired with pre-planned saw-and-seal joints against a premium, higher-cost upgraded asphalt without cut joints.
“With limited paving budgets, transportation practitioners need to make every dollar go as far as possible,” Marasteanu says. “Our goal was to see if standard asphalt with saw-and-seal joints could deliver premium durability at a significantly lower cost.”
The research team began with a literature review and statewide survey of 92 Minnesota local road agencies to document real-world practices, costs, and benefits. Next, they collected historical pavement condition and ride-quality records from four Minnesota cities (Shoreview, Roseville, Maplewood, and St. Louis Park) to evaluate how saw-and-seal sections perform over time.
“Local agencies reported that saw-and-seal generally performed well,” Marasteanu notes. “However, varied experiences suggest that local factors such as site conditions, mixture properties, and moisture susceptibility affect performance.”
Using computer simulations and a mechanistic and probabilistic thermal cracking model, researchers combined data on pavement strength, soil support, and winter weather contraction to evaluate how joint spacing impacts the formation of cracks. The model revealed that performance depends heavily on proper installation and subgrade conditions. Crucially, saw-and-seal joints succeed only if the underlying soil is well-drained; trapped water freezes and heaves, so subsurface drainage issues must be resolved prior to sawing. The model also identified a spacing of 30 to 40 feet as the optimal balance for controlling thermal cracks without overspending on labor.
Finally, a life-cycle cost analysis compared total 20-year costs — combining upfront construction and long-term maintenance — across various traffic levels, asphalt strengths, and project lengths. The results demonstrated clear cost-effectiveness of using pre-planned saw-and-seal joints for lower-cost asphalt. On typical local roads, premium asphalt costs roughly 34 percent more to install upfront; lower-cost asphalt with pre-cut joints delivers comparable long-term performance at significant initial capital savings. On long corridor projects exceeding 60 miles, however, bulk-material cost shifts make premium asphalt worth considering.
“These results confirmed current joint spacing practices used by metro cities and offered insight on the trade-offs associated with higher initial costs and future maintenance needs,” says Tom Wesolowski, City of Shoreview public works director and the project’s technical liaison.
Equipped with these findings, transportation practitioners now have an evidence-based framework to balance upfront paving costs with long-term road health — establishing saw-and-seal as a reliable, cost-effective crack-control strategy for lower-volume local roads when applied to the right candidates and constructed properly.