The City of Plymouth, Minnesota maintains a pavement network consisting of more than 300 centerline miles of bituminous surfaced streets. The network is comprised of low-volume residential streets, as well as some higher volume collector streets. To monitor pavement conditions, the city performs PASER ratings, which provide a qualitative rating between 1 and 10 based on surface distress. Pavement repairs performed by the city were mostly driven by surface conditions and the PASER ratings, and included crack sealing, edge mill-and-overlay, mill-and-overlay and reconstruction.
Multiple factors play into a well-maintained pavement network. With a clear understanding of these factors, the right repair treatment will be applied to the right roadway at the right time. For this reason, the city hired Braun Intertec to review their pavement management practices and to provide recommendations for better pavement network management. The city’s goal was to stretch their capital improvement plan (CIP) budget and help prolong their pavement lifespan.
When determining the proper repair treatment for a given street, it’s important to consider pavement surface condition, underlying pavement conditions, and pavement age. In addition, other extenuating factors may prompt a pavement project such as utility work, drainage improvements or capacity issues. Review of the City of Plymouth’s pavement management practices began with a complete review of the city’s pavement management data. This included an assessment of existing pavement surface condition ratings, a look at pavement age and construction practices, development of pavement performance curves and a review of capital improvement plans (CIP) funding allocations. Braun Intertec also reviewed the types of repairs performed by the city, as well as practices used when selecting the repair type. Once the review was complete, Braun Intertec recommended to the city incorporate several new pavement repair techniques.
In our review we also found the city’s preferred preventive maintenance was crack sealing. While crack sealing is an excellent preventive maintenance repair treatment that will help prolong pavement life, it is also important to incorporate a type of surface sealing repair, too. When surface sealing is performed, not only are smaller existing cracks or high air voids sealed, the entire pavement surface is improved through visual aesthetics, resistance to oxidation from the sun, and by replacing eroded surfaces. Both crack sealing and sealing treatments should be applied systematically to improve pavement surface quality and extend pavement life.
Braun Intertec also advised the city take earlier pavement maintenance measures. Prior to our project, the city performed edge mill-and-overlay and mill-and-overlay repairs extensively. While these types of repairs promote longevity of pavement life, when considering pavement age, these repairs are more beneficial when applied earlier on in the pavement’s life cycle. Braun Intertec also recommended that the city perform some investigative testing before any mill-and-overlay projects to confirm the selected repair is suitable for the street’s underlying conditions and that recycling repairs be considered and incorporated into the city’s toolbox of repairs when other circumstances, such as the need for curb and gutter or utility repairs, aren’t warranted. These repair options would reduce costs while still offering a design and lifespan similar to that of full reconstruction.
Finally, pavement specialists at Braun Intertec advised a shift in funding so a portion of the city’s capital improvement plan (CIP) budget would be reallocated to preventive maintenance and recycling repairs. The city has since successfully implemented a variety of improved pavement management practices to maintain their pavement network.
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