2024-020 - Pavement Managmenet Plan for Measure M2 Program

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4.0 Maintenance And Rehabilitation Strategies • Structural Overlay — Structural Overlays, which applies to moderate to severe pavement cracking with little or no deficiency in the foundation layers, entails cold -milling / grinding the surface to a depth of up to three inches for arterial streets and two inches for local streets, removing localized failed areas, and placing a thick layer of hot -mixed AC (typically four to five inches for arterial streets and three to four inches for local streets). The new AC pavement section smooth the ride performance, improves skid resistance, correct the crown and drainage features, increases pavement structural capacity. • Cold -In -Place Recycling (CIR) — CIR, which applies to moderate to severe pavement cracking with little or no deficiency in the pavement structure, is a process rehabilitating pavement by recycling it in place. The top layer of pavement is removed with a milling (grinding) machine to a specified depth (typically three to four inches). The removed material is then crushed, sorted and mixed with a specially formulated asphalt emulsion. This emulsion mixes with the milled pavement and acts as a binder to form the new CIR pavement. This new mixture is placed on the roadway by a paver and compacted as a new and more durable asphalt base course. Finally, a thin overlay of conventional asphalt pavement is placed over the CIR to seal it and provide a new wear to improve ride performance and drainage features and increase pavement structural capacity. • Cement -Treated Base (CTB) — CTB is applicable when the distress evidence at the surface indicates failure in the pavement structure or subgrade (the roadway completely failed with crumbling surface pavement), which is not correctable by less extensive construction. Due to its long curing time, this treatment method typically should be applied to low -moderate traffic areas and/or moderate traffic areas with more than one lane per direction with a low volume of large vehicles. CTB involves grinding the existing roadway surface and base into pieces to a prescribed depth (typically 14 to 20 inches for arterial streets and 8 to 11 inches for local streets), which are mixed with cement and water to be used as a base course. A thin overlay of conventional asphalt pavement is then placed over the CTB base to provide a new wear for improving ride performance and drainage features and increase pavement structural capacity. • Full Depth Reconstruction (FDR) — FDR is applicable when the distress evidence at the surface indicates failure in the pavement structure or subgrade (the roadway completely failed with crumbling surface pavement), which is not correctable by less extensive construction. This treatment involves removal of existing layers of asphalt AC, PCC, and/or base to a prescribed depth recommended by geotechnical engineering pavement analysis and placement of conventional flexible pavement section. In general, local residential and non-residential streets are removed to depths of six inches and eight inches, respectively; a depth of 10 inches are removed on secondary arterial and collector streets; a depth of 12 inches are removed on primary arterial streets; and a depth of 16 inches are removed on major arterial streets. The actual depth depends on anticipated traffic loading, soil conditions, and roadway functional classifications. This treatment is by far the most expensive form of M&R strategies to increase pavement structural capacity. City of Santa Ana 2024 Pavement Management Program 4-4-2