Pavement Management Program Benefits Campus Network
BY Jennifer Tran, P.E.
Managing more than 15 million square feet of pavement would be a daunting task for any facilities team, but it’s especially complex when 32 campuses and 16 facilities managers are involved. This is the scenario for a client of Terracon Consultants Inc., headquartered in Olathe, Kansas. The client is Maricopa County Community Colleges, the largest U.S. community college network. Based in Tempe, Arizona, the Maricopa County Community College District (MCCCD) includes 10 regionally accredited locations serving more than 200,000 students each year.
Successful deployment of a long-term pavement management plan has resulted in substantial cost savings and operational efficiencies for the college network. This systematic approach allows for consistent field data collection and processing.
The plan is built upon annual evaluations of pavement condition based on regularly scheduled inspections of sample units at the network level and project level. For each sample unit, the Terracon team determines the type, amount and severity of pavement distress present. Distress survey information is entered into software to determine pavement condition indices (PCI) and ratings for each pavement.
Based on the PCI, the team prioritizes pavements into four categories that need various levels of maintenance or rehabilitation. The results of the PCI and the recommendations are then used to develop a rolling five-year budget. As part of Terracon’s services, the team also prepares the plans, specifications and contract documents recommended in the management plan.
Consistent with good pavement management practice, maintenance and preservation projects dominate the annual pavement program, which includes large areas of crack sealing and surface treatments. Because the work is on college campuses, construction occurs during Arizona summers when temperatures of the asphalt pavement exceed 155°F. Materials and application of products are specified to meet certain criteria (i.e. temperature) prior to placement.
With extreme conditions in Arizona, asphalt pavements undergo large temperature fluctuation and can become distressed, and cracking in the pavement surface is the primary distress. Rubberized asphalt crack sealant, formulated for the Arizona climate, is used to seal cracks between one-quarter inch to one and one-half inches in width.
Crack mastic products are also used. While crack sealant and crack mastic have the same objective, crack mastic sealant is typically used to fill cracks greater than one and one-half inches in width. Crack mastic sealant contains binders with aggregate, synthetic rubber polymers and other modifiers. As such, cracks should be wide enough to accept the pea gravel-sized aggregate and still provide a good bond for the sealant to adhere to each side of the crack. After given sufficient time to cure, crack mastic sealant provides a more rigid final product and is less susceptible to the heat and impact from vehicular and pedestrian traffic compared to crack sealant.
Projects on the campuses are also dominated by global surface treatments, which include slurry seal, fog seal and micro surfacing. The objective of a global surface treatment is to provide a new wearing surface and to protect the pavement surface from weathering, especially from the damaging oxidation of the sun’s UV rays.
Micro surfacing is the preferred product by the Colleges due to low levels of aggregate loss and the relatively quick curing time, typically within hours. According to U.S. Department of Transportation Federal Highway Administration (FHWA), micro surfacing treatment can extend the useful life of existing pavements, which are still considered in good condition, by three to seven years. Based on our experience with the MCCCD project and pavements within the Phoenix metropolitan area, micro surfacing treatments are typically scheduled for re-application every five to six years.
Micro surfacing material specifications require a mixture of cationic polymer modified asphalt emulsion, mineral aggregates, cement and other set controlling additives. Isolated asphalt patching is also another common form of preventive maintenance repair. While patching is an option, we limit the patching to repair areas with fatigue cracking and potholes. Once pavement conditions become fair or poor, thin pavement overlay or a mill and overlay can be considered to extend the pavement useful life by five to 12 years.
Due to our involvement with the project since 1995, we collected field data to determine PCI for every pavement section owned by the MCCCD and included annual construction costs. These accumulated values are graphed to show cost savings over time by implementing a pavement program.
With a pavement management program, the average overall PCI is maintained in the mid-70s range—satisfactory to the client—despite additions of deteriorated pavement from acquisition of new properties. Without a pavement management plan, the average overall PCI declines to the 20-point range, which is considered “serious” according to ASTM standards and would require extensive repairs.
Though facility managers and property owners may find it challenging to capture the return on investment of a pavement management program, the results can be significant. The MCCCD estimates it has saved more than $30 million by maintaining the average overall PCI at an acceptable condition. If you consider the pavement management implementation expense of $2 million, this means the MCCCD has made a 1,500 percent return on investment by use of Terracon’s program.
Terracon’s experienced team of pavement professionals provides clients with a full range of pavement services. Helping clients effectively manage assets can include evaluation and maintenance, to recommendations for existing pavement rehabilitation and replacement.
Jennifer Tran, P.E., is a senior project manager and office lead in Terracon’s Avondale, Arizona, office with more than 14 years of experience in geotechnical and pavement engineering and design. Her responsibilities include project design and management, client management, and proposal preparation.