Strategic Solutions: Airport Pavement and PCI Reports

Strategic Solutions: Utilizing your Airport’s Pavement Condition Index (PCI) to Maximize the Useful Life of your Airport’s Pavements

As inflation is on the rise in the United States, the cost of aviation projects like taxiway and runway rehabilitations continues to follow this trajectory, with inflation rates of 20% since 2021. There are numerous reasons for this rise in costs, being materials, shipping, labor shortages, etc. These inflation catalysts are not easily controlled, but how you maximize the useful life of the airports’ pavement to save money and resources long term can be. In this article, we will delve into what a Pavement Condition Index or PCI is, how to interpret the report, and ways to save money by planning maintenance instead of reconstruction. Developing a proper Pavement Management Plan (PMP) by utilizing findings and recommendations from your airport’s PCI report is one way to cut back on major pavement reconstructions and extend the longevity of your runways and taxiways.

Pavement Condition Index (PCI)

Pavement Condition Index inspections and scoring was first developed by the U.S. Army Corps of Engineers in the mid-1970’s in an effort to have an objective, repeatable system to be able to not only quantify the current condition of pavement but to also predict its future condition (Shahin, 1994).  The PCI score is created from a visual inspection of pavement distresses.  A distress is defined as any imperfection in the surface of a pavement, such as a crack, a rut, shattered slab, aggregate pop-outs, etc.  These distresses are assigned a distress type, a quantity of the distress, and a severity level (low, medium, or high).  These three items are used to then calculate the current Pavement Condition Index, or PCI, of that pavement area.

Asphalt and PCC airfield pavements are inspected every three to five years and assigned a “score” based on the quantity and severity of various pavement distresses.  This score is called the Pavement Condition Index (PCI) and is an invaluable tool for tracking pavement maintenance projects for your airfield. The initial PCI starts at 100 when the pavement is brand-new and will fluctuate down from there. The “critical PCI” is the number at which the pavement has been used for 75% of its useful life which is between 60 and 70.

Figure 1: L&T Cracking Deduct Curve (Shahin, 1994)

During a typical PCI survey, inspectors will physically walk your airport’s entire pavement.  They will inspect a pre-determined number of samples within each pavement area branch that will provide an objective average of the typical distresses of that pavement branch. Each severity of every distress carries with it a certain “deduct value”, or a calculated number that will be subtracted from the initial PCI of 100. Prior to the convenience of computer technology and the advent of the PCI program PAVER that performs the necessary calculation for us, logarithmic curves for each distress and each severity were used to establish the deduct value.  Shown above are the deduct curves for Longitudinal/Transverse (L&T) cracking in asphalt pavement.  You can see how what may seem like a minor distress could have major impacts on your score and why crack sealing is so critical in extending the useful life of your pavement.  For example, if your pavement area has 10% medium severity L&T cracking, 35 points are taken from your PCI, meaning if that is the only distress (unlikely to be the case) your PCI drops to a 65, at or below the critical PCI.  After crack sealing, the distress is still there, just now at a lower severity, improving your PCI from 65 to 78, back above critical PCI.

How Do I Interpret My PCI Report?

Most airports in the state of Alabama have a PCI report developed under ALDOT Aeronautics Statewide Airport Pavement Management Program or have their PCI scores available to them at ALDOT’s GIS website.

1. Why is my pavement divided into so many different areas?

The first thing you may notice is that your pavement areas, such as your runway(s) and taxiway(s) may be divided into different sections.  The primary reason for this is that the pavement may have different construction histories, such as a taxiway/runway extension.  In doing so, your one area will have two different ages of pavement.  For instance, your main parallel taxiway last received maintenance 10 years ago, but you did a taxiway extension two years ago.  Would you do a mill-&-overlay on the extension at the same time as the rest of the older pavement? Probably not, as that would not be a recommended use of your funds.  Therefore, inspectors will usually separate these areas into different “Branches,” as they are referred to in your report, and each Branch is assigned its own PCI score and recommended maintenance schedule.

2. What do all these colors mean on my airport’s PCI report?

Figure 2: PCI score categories

At first glance, it can be slightly overwhelming with the up to seven different colors shown over your airport-owned pavements. But what do they mean, and how do I use them to develop my Pavement Management Plan (PMP)?  On a typical PCI report, the pavement condition will be shown as one of seven categories, shown in Figure 2 to the right. As was mentioned before, distress in the pavement causes the PCI score to be lowered, and the amount is dependent on the severity and type of distress. You preferably want to keep your pavement between 70 and 100 PCI for as long as possible. Using these scores can help you develop your PMP and decide what mediation is needed for each area of pavement.

3. How do I implement the PMP into my CIP?

At the end of your airport’s PCI report, you will likely see a section with recommended projects (similar to Figure 3 below). This section of the PCI report is developed by setting an annual Maintenance and Repair (M&R) budget and/or, an unlimited budget, i.e., what it would cost to bring your entire airfield pavement above critical PCI.  Using the limited budget section, start by first programming all the recommended projects into your CIP.  You can then remove projects or add projects based on your airport’s specific annual budget.  It is possible that due to a limited budget scenario, a mill-&-overlay will not be shown when one is warranted.  In such a case, it is advisable to add the mill-&-overlay into your CIP and push all PCI report-recommended projects back one year.

In your project recommendations, you will see the terms Local Stop-Gap, Local Preventive, Global Preventive, Major Above Critical, and Major Below Critical.  These terms are used instead of giving specific rehabilitative effort recommendations, as that will be up to you and your engineer to determine the exact method to use.  Below is what each M&R category means, and what type of rehabilitative method might be expected.

Maintenance & Repair (M&R) Categories
Local Stop-GapProgrammed to be minimum amount of money to be spent to maintain usable airfield (will not improve PCI)
Local PreventiveIntended to not improve PCI, but slow rate of deterioration at the “Local” level, or small area(s) of Section
Global PreventiveIntended to not improve PCI, but slow rate of deterioration of entire Section or Branch
Major Above CriticalM&R performed to improve PCI on pavements above critical PCI.  Usually mill & overlay or reconstruction
Major Below CriticalM&R performed to improve PCI on pavements below critical PCI.  Usually mill & overlay or reconstruction
Table 1: Maintenance and Repair (M&R) Categories

Branch IDSection IDAvg of Condition BeforeAvg of Condition AfterWork TypeTotal Cost
WEST TW.W664.9765.19Local$7,560.36
AIR CARGOPHASE 3B68.5168.69Local$7,750.44
OPS & MAIN(i)31.5131.51Stop Gap$8,013.66
AIR CARRIE(1)B75.5175.52Local$9,976.83
WEST TW.W359.2159.24Local$10,198.20
WEST TW.W769.3769.46Local$10,580.91
WEST TW.W156.7656.80Local$11,489.71
AIR CARRIE(1)A73.0773.09Local$12,612.52
GEN, AVIATGA APRON43.2843.28Stop Gap$14,220.32
WEST TW.W(a)34.3134.31Stop Gap$19,152.52
OPS & MAIN(c)16.9116.91Major Under Critical$21,157.38
RW 18L-SHOULDERS167.6967.77Local$21,798.21
RW 18L-SHOULDERS267.6967.77Local$21,789.21
RW 19L-SHOULDER1A62.6062.64Local$24,572.84
AIR CARGO(2)62.7062.74Local$29,570.55
CORP. APRO(1)63.3363.38Local$33,030.24
WEST TWW(a)169.5669.66Local$34,545.12
AIR CARGOPHASE 267.2067.28Local$36,957.16
WEST TWL27.7027.70Stop Gap$37,935.94
AIR CARGOPHASE 4A64.7865.09Local$49,819.82
Figure 3: Sample PCI Report Project Recommendation; 2023

Pavement Maintenance over Reconstruction

Spending your time and money towards maintenance programs rather than letting them fall behind to the point of reconstruction needs is another great way to save money in the long term. In 2022-2023 alone, ALDOT spent $4.5M on pavement maintenance which in turn will save them about $18-20M in reconstruction needs down the line.

Shown below is the typical life cycle of asphalt pavement. As you can see, asphalt pavement experiences a 30-40% drop in quality over the first 75% of its design life (typically 20 years).  However, at this point, known as the “critical PCI,” the quality of the pavement drops another 40%, but this time, in a mere 12% of its useful life.  At the end of this time, a complete reconstruction of the pavement is warranted, costing millions of dollars and requiring extremely lengthy pavement closures, potentially costing your airport another few million dollars in lost revenue through landing fees, fuel sales, etc.

How Implementing a Pavement Management Plan Can Save You Money

So, how can we extend the life of our asphalt pavement, and how do we know when is the correct time to perform this work?  Let us assume that one of your taxiways has just received a major overhaul, either a mill-&-overlay, reconstruction or even brand-new construction. When is the best time to plan for maintenance work on this area again?  Once a paving project is complete, it is recommended to put a crack seal/seal coat project for this area at Year 5 of your Capital Improvement Program (CIP) as it can be predicted that five years (+/- three years depending on the outcome of PCI inspections) after initial paving, the first round of maintenance will be needed. This first round will likely consist of sealing pavement cracks and an application of a sealcoat. After this initial round of pavement maintenance and after another five years (+/- three), the second round of pavement maintenance would need to occur. Similar to the first round, this would likely comprise a second round of crack seal and a sealcoat, or perhaps a chip seal or slurry seal if your PCI indicates a heavier rehabilitative method is required (or most beneficial), based upon the severity of pavement cracking.  Eventually, a pavement mill-&-overlay will be required. 

The graph below illustrates the new life cycle of asphalt pavement when a proper pavement management plan is incorporated (in purple) compared to no pavement management plan. As can be seen, even with three pavement rehabilitation projects complete over the same 20-year life cycle of the pavement, much less funding has been required to maintain the same pavement. 

Now you may be wondering, sure, I can get AIP funding for the taxiways and runways, but what about my aprons and taxilanes that do not have priority for AIP/AIG funding? The good news is, ALDOT has recently implemented an annual pavement rehabilitation program that provides crack sealing and/or seal coating to these areas of pavement that are difficult to secure federal funding for.  This program is a 75% State/25% Local match program that you can apply for through ALDOT.  For larger maintenance projects, ALDOT has a 50/50 match program that you can apply for if AIP/AIG funds are unavailable. Lastly, ALDOT will be conducting PCI report updates/inspections in 2024/2025, so be sure to be on the lookout for communication from them on when your airport is scheduled for inspection! Once you have received your report, and you find yourself with more questions than answers, please do not hesitate to reach out to us at AVCON, and we will be happy to walk you through your report!

References:

Shahin, M. (1994, August 31). Pavement Management for Airports, Roads, and Parking Lots. Springer.

Eric Roden, PE, CM

Aviation Project Manager

Eric Roden, PE, CM has over 10 years of experience in project management, pavement condition index inspections, design development and management, bid and construction administration, geotechnical and material testing, and client development. As an Aviation Project Manager at AVCON, Eric is responsible for airfield design, construction cost estimation, bidding administration, site inspections, material testing oversight, and more. He graduated with his B.S. in Civil Engineering from Auburn University, is currently pursuing a M.S. in Aerospace Leadership and Policy, is a registered Professional Engineer with the State of Alabama and is a Certified Member of the American Association of Airport Executives.

In 2014, Mr. Roden was first trained to perform PCI inspections and author reports at the Air Force Civil Engineering Center at Tyndall Air Force Base by Army Corps of Engineers staff as well as by the founder and principal researcher of the PCI method, Dr. M. Y. Shahin, and has performed PCI inspections at airports throughout the Southeast.