Quick Overview of Pavement Conditions & City Paving Program
The City of Suisun City operates and maintains 76.7 centerline miles and manages 13.4 million square feet of pavement that connect commuters safely in, out, and around our town. Road maintenance requires substantial planning, expertise, funding, and staff support. The City’s Public Works Department manages these tasks with Council authorizing funds for roadway projects, as available. Please see the Reference Section for how the various streets in town are categorized, based on their volume of traffic. Note that each City street is not built the same and therefore does not share the same deterioration curves or have the same life expectancy. For example, the useful life for an arterial street is much shorter than a residential street which is due to the amount of traffic.
The Public Works Department relies on a grant from the Solano Transportation Authority (STA) to fund a Pavement Management Technical Assistance Program (P-TAP) report, produced by a consultant, roughly every two years. This report serves as a guiding document to the City and Council in providing details and a overview of current pavement conditions and needs within the City. It also offer multiple funding scenarios and how those scenarios impact the City’s overall Pavement Condition Index (PCI) score in the short and long term.
To create the report. the consultant gather data from City staff and from the City’s existing Pavement Management Program (PMP) software. The P-TAP consultant examines the City’s roads to determine their condition and the type of maintenance needed. It assigns each roadway a PCI score and also determines the City’s overall average PCI score. A chart explaining each PCI score range is provided below along with a chart showing current City pavement conditions is provided below in Figures 1 and 2. Data provided on this page is pulled from the City’s 2020/2021 P-TAP Report.
Figure 1 – Pavement Life Expectancy – PCI Score Range
Figure 2 – City’s Current Pavement Conditions (Overall PCI score in each category)
The most recent report from 2020/2021 states that the City’s overall PCI score is “58” which means that the City’s streets, on average, are in the “At Risk to Poor” category.
Figure 2 above illustrates that:
• 36.4% (approximately) of the City’s roads have a PCI score of “70 to 100”. --> “Good to Excellent” category.
• 30.1% (approximately) of the City’s roads have a PCI score of “50 to 69”. --> “At Risk to Fair” category.
• 21.9% (approximately) of the City’s roads have a PCI score of “25 to 49”. --> “Poor” category.
• 11.6% (approximately) of the City’s roads have a PCI score of “0 to 24”. --> “Failed to Very Poor” category.
The cost to repair the City’s current backlog of streets that are need of repair is $39.4 million for the year the Report was published (2021). The Report estimate for 2023 was $54.3 million, and keep in mind the dramatic increase in materials costs which started in late 2021/early 2022.
Even based on out-of-date numbers, it is clear that the planning, expertise, and staff support necessary to maintain the quality of our roads requires significant funding which the City does not have available. The City has only received an average of $645,000 annually in Gas Taxes which are funds from the State over the last four years. These funds not only cover the cost of roadway maintenance and repairs but also cover: streetlights, signs, sidewalk/curb & gutter, curb ramps, roadway striping, and filling potholes. The funds referenced above are “Gas Tax” funds the City receives each year. The only other funding source is the General Fund/Measure S. The City faces a deficit each year that impounds upon itself each fiscal year, and this is compounded with the dramatic reduction in Gas Tax revenue due to electric vehicles and other factors which are out of the City’s and/or the State’s hands. Each year the City is short the millions and millions of dollars need to keep the City’s roads adequately maintained. Due to the significant lack of adequate funding, the number of “Good to Excellent” roads are decreasing while the “At Risk to Fair,” “Poor” and “Failed to Very Poor” roads are increasing. Once a road starts to deteriorate into the “At Risk to Fair” category, the costs for repairs spikes significantly, and often puts it out of the City’s reach for repairs so that, if and when funds available, they are funneled toward maintaining the streets in the “Good to Excellent” category.
Due to severe budget restraints faced by the City, it is important that staff strategize which roads to address to ensure the small amount of funds available are having the greatest impact. Details of the various repair methods employed for street within each PCI category is provided in the Reference Section below.
When selecting street segments for roadway projects, staff selects street segments that minimize disruption to residents, avoid conflicts with other upcoming City projects within the roadways, avoids paving ahead of utility projects, and are located near other project locations to minimize mobilization time for contractors. Road maintenance projects also include: re-striping of the roadway, sidewalk repairs, installing accessibility ramps in intersection, repairing storm water drains, adding bike lanes, and more. As is typical of paving projects, construction will cause temporary or intermittent delays to traffic in the work areas during paving operations, however, staff does its best to ensures the impacts are minimized and that public safety is held as the highest priority.
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Reference Section
How are City Streets Categorized?
All cities roadway networks are classified into four functional classifications of roadways based primarily on the volume of traffic on a given street:
- Arterial
These roadways provide a high degree of mobility while allowing direct access to abutting properties. These roadways serve major activity centers in an urban setting and have the highest volume and longest trip demand within a city. They interconnect other major corridors to accommodate trips entering and leaving the City. These roads also serve the need for “intra‐area” travel between the business district and outlying residential areas. An example of an arterial in Suisun City is Walters Road. Also, Arterials primarily serve intra‐urban or local travel, carrying traffic from Collector streets to and from other parts of the City and limited access roadways. Access to properties bordering these streets is subordinate to the primary function of moving traffic.
- Collector
The primary function of Collector streets is a combination of access and mobility. These streets provide links between Local streets and Arterials. They are designed to serve neighborhood traffic rather than cross‐town traffic, including trips between adjacent neighborhoods. The design speed for collectors is typically 35 miles per hour. On‐street parking is usually provided. An example of a collector in Fairchild Drive.
- Residential/Local
Unlike other categories, local roads are not intended for long‐distance travel except at the origin or destination end of a trip. Local roads provide the highest level of accessibility and carry no through traffic movement. The primary function of local streets is access to adjacent land uses. Parking is usually offered along local roads, and speed limits are typically 25 miles per hour.
- Other - These segments are pavements that are owned and maintained by the City. These types of pavements are typically parking lots and trails and should not be tabulated into the City’s network.
Road Maintenance Methods & Strategies
Sample Types of Treatments for Roads with a PCI Score Between 70 ‐ 100
Crack Sealing
Surface Crack is an inevitable distress and is one of the first signs of distress that occurs at the pavement surface. If this distress is neglected over time, it can grow to a pothole and eventually sub‐base failure if left untreated. Crack Sealing is a cost‐effective treatment and can treat all types of cracks greater than 1/8”. This treatment slows the deterioration and can extend a pavement life three to five years.
Fog Seals
Fog Seal is a single application, typically light, of emulsified asphalt to an existing asphalt
surface. This maintenance treatment can be used to renew an oxidized road (weathered),
improve the surface appearance, seal minor cracks and surface voids, and inhibit raveling. This treatment extends the pavement life two to four years.
Slurry Seals and Microsurfacing
Slurry seal and microsurfacing is a surface treatment are mixtures containing asphalt emulsion, graded aggregates, fillers, water and other additives to control the break and set time of the mixes. These treatments are designed to extend the life of asphalt pavements in good condition by providing skid resistance, restricting moisture intrusion, protecting the structure from further oxidation and raveling, and restoring a uniform black appearance. The slurry seal provides quick construction times and minimal disruption to the traveling public and can extend the life of the pavement by five to seven years. Microsurfacing extends the pavement life six to eight years.
Ultra‐Thin Lift HMA
An ultra‐thin lift HMA is a hot mix asphalt treatment consisting of paving grade asphalt and aggregate. Ultra‐thin lift asphalt treatments are generally applied at a compacted depth of .75” to 1” on roads in good condition. This pavement preservation application provides a smooth surface while addressing raveling, low‐severity top‐down cracking, and oxidation. This treatment can extend the life of the pavement eight to ten years.
Sample Types of Treatments for Roads with a PCI Score Between 60 – 90
Chip Seal
A chip seal is a roadway surface treatment that consists of a layer(s) of asphalt binder (hot or emulsion) with a layer(s) of embedded aggregate. Chip seals provide a new skid‐resistant wearing surface, stops raveling, seals minor cracks, and retards further deterioration of the existing roadway. Chip seal binders can be polymer‐modified to improve aggregate retention and provide for a quicker return to traffic. This treatment can be used on roads with a PCI of 60 and above and can extend the pavement life five to seven years.
Cape Seals
A cape seal is a roadway surface treatment designed to extend pavements' lives in fair to
good condition, consisting of a chip seal treatment covered by a slurry seal or microsurfacing treatment. Cape seals provide the benefits of both the chip seal and the
slurry seal or micro surfacing treatment, namely sealing moderate cracks, providing skid
resistance, sealing the pavement against moisture intrusion, protecting the structure
further oxidation, and raveling, and restoring a uniform black appearance. Cape seals boast short construction times and reasonable disruption to the traveling public. This treatment excels in urban areas where stand‐alone chip seals are not be welcomed, but the need for sealing cracks is warranted. This treatment can be used on roads with a PCI of 60 and above and can extend the pavement life eight to ten years.
Hot In‐Place Recycling
Hot In‐Place Recycling (HIR) is on‐site, in‐place pavement preservation and corrective
maintenance technique that can be classified as structural rehabilitation when combined
with an asphalt overlay. There are three sub‐disciplines of HIR; Surface Recycling, Remixing, and Repaving. All HIR sub‐disciplines consist of heating, softening, scarifying/hot milling, mixing, placing, and compacting the existing pavement. Rejuvenating agents and additives can be integrated into HIR mixtures to improve the characteristics of the recycled pavement. HIR should be considered whenever mill and fill or a leveling course is required before an asphalt overlay. This treatment can be used on pavements with a PCI of 60 or greater and extends the life by seven to fifteen years.
Sample Types of Treatments for Roads with a PCI Score Between 55 – 69
Scrub Seal
A scrub seal is an application that is very similar to a chip seal treatment. The only difference
is that the asphalt distributor pulls a broom sled that houses a series of brooms placed at different angles. These brooms guide or "scrub" the emulsion into cracks that ensure the road will be sealed. This treatment can be used on the road with a PCI of 55‐70 and can extend the pavement's life for six to seven years.
Sample Types of Treatments for Roads with a PCI Score of 54 or less
Cold‐in‐Place Recycling
A cost‐effective, long‐lasting, greener alternative to conventional maintenance and rehabilitation techniques. Cold In‐place Recycling (CIR) is a process that cold mills and recycles the top 2‐5 inches of asphalt using a continuous train operation. CIR significantly reduces trucking, time, and natural resources to substantially lower project costs by reusing existing material. Generally, any road that is a candidate for mill & fill is a candidate for CIR. This treatment adds fifteen‐twenty years with a combined appropriate wearing course. This treatment is typically 20%‐50% less expensive than conventional maintenance and reconstruction methods.
Cold Planing
Cold Planing (CP), commonly referred to as milling or profiling, is the controlled removal of an existing pavement's surface to the desired depth or cross‐slope with specially designed equipment capable of removing portions of the pavement surface to the specified grade and cross‐slope. CP can be used in excavation, reconstruction, rehabilitation, and maintenance operations. This treatment extends the life of the pavement structure by correcting smoothness issues, drainage issues and removing some top‐down cracking and raveling.
Full Depth Reclamation Reconstruction
A cost‐effective, long‐lasting, greener alternative to deep rehabilitation or removal and replacement techniques. Full Depth Reclamation (FDR) is an engineered rehabilitation technique in which the full thickness of the asphalt pavement and a predetermined portion of the underlying materials (base, subbase and/or subgrade) is uniformly pulverized and blended to provide an upgraded, homogeneous material. The reclaimed materials may be improved and strengthened by using Mechanical, Chemical, or Bituminous stabilization. FDR isn't only for roads in poor condition; it is also a viable design process for increasing pavement's structural capacity in good condition.