Pavement Design

Pavement Design | LCCA Projects

Metro District LCCA Projects

Metro District Comments

SP 2738-31, MN 101, Letting date 1/19/2027

SP 6220-96, US 61, Letting date 9/24/2027

SP 1929-50, MN 77, Letting date 3/27/2026

SP 1926-23, MN 316, Letting date 12/6/2024

SP 2713-129, US 12, US 12, Letting date 9/26/2025

Comment from Brandon Brever, Minnesota Asphalt Pavement Association (MAPA), bbrever@mnapa.org 10/31/2024

Minimized Local Disruption: Asphalt paving allows work to be completed in phases with fewer extended closures. This speed of construction means that local traffic, businesses, and communities experience fewer disruptions. Asphalt can be paved in short time windows (overnight or during off-peak hours), which is less disruptive to daily routines and minimizes impacts on local commerce, something particularly important in business corridors. Asphalt can be used by traffic almost immediately after compaction, ensuring minimal downtime.

Efficient Maintenance with Traffic Open: Over a pavement’s life cycle, asphalt maintenance can be executed with minimal impact to traffic. Asphalt overlays, scheduled at intervals like year 20 and year 37, can often be applied while keeping lanes open, allowing for a smoother driving experience with fewer full closures. In comparison, the concrete life cycle requires major concrete pavement removal and replacement at year 20 and 35.

Enhanced Ride Quality Over Time: Asphalt overlays improve ride quality during maintenance without requiring extensive reconstruction. Asphalt’s smooth surface ensures consistent ride quality and addresses minor defects efficiently. This is beneficial for the traveling public by providing a smoother, quieter driving experience.

Select Granular Base Requirements:
Another key point to consider is the difference in base requirements. The asphalt alternative includes a 22-inch select granular sand subbase, compared to the 12-inch select granular subbase for concrete. This thicker granular base provides additional flexibility and strength, contributing to a more stable and durable foundation over time. The increased base depth with asphalt serves to enhance drainage and prevent subgrade issues, especially in regions prone to freeze-thaw cycles, which can cause pavement heaving and cracking. This extra base support not only extends the life of the pavement but also helps reduce maintenance needs by preventing early-stage foundation issues. In addition, the thicker base can help distribute loads more effectively, and limit the amount of strain in base layers. This contributes to long-term quality and provides a robust structure that can then limit any distress to the top layers of asphalt. Mill and overlays can then be used at typical intervals to prolong the overall structural integrity of the section.

Environmental & Resilience Benefits:
HMA pavements are compatible with high recycled content (100% of asphalt pavements are recycled), contributing to sustainability goals. Utilizing RAP (Recycled Asphalt Pavement) aligns with environmental objectives by reducing the demand for virgin materials and lowering carbon emissions associated with production. With climate resilience becoming a significant consideration, asphalt’s adaptability to various weather conditions and potential for innovative additives (e.g., warm-mix asphalt technology) make it a forward-looking choice. The choice of HMA aligns with future requirements to adjust to evolving climate conditions or state and federal funding priorities that prioritize resilient infrastructure.

While continuity along corridors is desirable, other factors like business impact, community access, and reduced congestion are vital to consider in urban and suburban settings. Given these benefits, asphalt provides an efficient, adaptable, and locally sensitive solution that supports businesses, keeps traffic moving, and can be maintained with minimal disruption over its lifecycle.

Pavement Design Engineer responses, 11/25/2024

"In comparison, the concrete life cycle requires major concrete pavement removal and replacement at year 20 and 35."

Response: The concrete life cycle requires Concrete Pavement Rehabilitation (CPR) at years 20 & 35, there is no concrete pavement removal in the 50-year analysis period when the concrete design life is 35 years.

"Select Granular Base Requirements..."

Response: Select granular sand subbase is a structural requirement and reduces stresses and strains on the subgrade, especially during spring thaw. Due to the load-bearing characteristics of concrete pavement a thinner subbase section can be used.

"While continuity along corridors is desirable, other factors like business impact, community access, and reduced congestion are vital to consider in urban and suburban settings..."

Response: Continuity along corridors also helps with more uniform snow and ice control since bituminous and concrete are treated differently from late fall to early spring.

SP 0208-169, MN 65, Letting date 2/1/2026

Comment from Dan Labo, P.E., Concrete Paving Association of Minnesota (CPAM), djlabo@cpamn.com 10/8/2024

This is within 10% on the LCCA (even with 6” concrete shoulders vs 4” asphalt shoulders). I know the locals tend to prefer concrete, so I’m hoping the final pavement selection is the concrete option? Please confirm, and if nothing else, we definitely want alternate bid if not concrete pavement outright.

Pavement Design Engineer responses 11/5/2024

"I know the locals tend to prefer concrete, so I’m hoping the final pavement selection is the concrete option?"

Response: The final pavement selection will be the low cost option of bituminous.

"Please confirm, and if nothing else, we definitely want alternate bid if not concrete pavement outright."

Response: The district will be requesting an exception from alternate bid. Ultimately, after discussion with agency stakeholders and consideration of project schedule and budget, it was agreed that maintaining diligence in delivering this project and achieving the expected corridor safety improvements is a top priority. Please note that future alternate bid opportunities are being reviewed by the district.

SP 1923-48, MN 50, Letting date 12/5/2025

Comment from Dan Labo, P.E., Concrete Paving Association of Minnesota (CPAM), djlabo@cpamn.com 10/8/2024

It looks like the ‘whitetopping’ option is 7” for a 20-year concrete design. 4” of bituminous get’s 20-years too, so this LCCA is obviously wrong. I’d imagine a true 20-year concrete whitetopping would come in about 5-5.5” thick, and the 7” is at least a 35-year design (it should get credit for that at least). This job highlights the bigger issue I’ve mentioned before of the new MnPAVE rigid only outputting 7” minimum pavements. Please let me know when a corrected LCCA will be issued, as this one is pretty egregious.

Pavement Design Engineer responses 11/5/2024

"4” of bituminous get’s 20-years too, so this LCCA is obviously wrong."

Response: This project is a 4” mill & 4” HMA overlay. The expected life of a 4” mill and 4” HMA overlay is less than 20 years on this aged pavement structure. Per the PDM Section 710, all HMA overlays 5.0-inches or less are included in the DL <20 years. Related to consideration as a 4” HMA reconstruction, a 4 inch design will not satisfy MnPAVE requirements.

"I’d imagine a true 20-year concrete whitetopping would come in about 5-5.5” thick"

Response: A BCOA-ME design comes out at 4.5 inches and a revised LCCA shows the 4.5” PCC whitetopping is 137.7% higher than the low cost alternate #1.

"This job highlights the bigger issue I’ve mentioned before of the new MnPAVE rigid only outputting 7” minimum pavements."

Response: MnPAVE Rigid is based on doweled PCC pavement from MEPDG 1.1 and CPAM did not want 6-inch doweled PCC pavement.

"Please let me know when a corrected LCCA will be issued, as this one is pretty egregious."

Response: You are welcome to present your own LCCA with supporting data for this project.

SP 1002-124, MN 5, Letting date 6/30/2025