Anyone can look at a blood pressure reading, check the chart and then tell you if there’s a problem. But it takes a medical professional to look deeper and determine why that person’s blood pressure is so high. And then to prescribe the best remedy to rehabilitate that person back to health based on their overall condition and lifestyle.
An airport’s pavements are critical as well, but the standard approach of treating them is to conduct Pavement Condition Index (PCI) testing, check the ratings and then apply the textbook rehabilitation method. PCI’s are still an essential component of a pavement management plan (PMP), but there have been major advancements in how PMPs can be conceived and prepared. You could be getting a much better, long-term prognosis for your pavements.
“If you come at pavement management from a design and construction perspective, you get a much more comprehensive look at everything that is actually involved. Not only will you be able to determine the optimal repair method, you’ll also be to develop phasing plans that minimize operational impacts and maybe most importantly, deliver more accurate cost estimates to help balance out budgets and take advantage of available funding,” said Chuck Taylor, senior aviation engineer, Crawford, Murphy & Tilly Inc.
Taylor has been around airport pavements for over 30 years. One thing he hears a lot from the airport directors he works with is their frustration when, after obtaining funding for a project and getting buy-in from their partners, the preliminary engineering report comes in and they discover that it will cost much more than expected. At that point, despite having had a PMP to guide them, it’s back to the drawing board.
“That’s a scenario that can largely be avoided when the people who are preparing the pavement management plan can implement some of that engineering and construction expertise into the process. Spending a little more time during the planning process can produce big dividends when it comes time to execute a project. It’s just a matter of taking a deeper look at the pavements and all of the factors that play into it,” Taylor said.
Taylor works for Crawford, Murphy & Tilly where they’ve developed a practical pavement management approach to PMPs over the past couple of decades. It evolved in response to changes in the industry, in particular, in regard to available funding. Where once airports could schedule major rehabilitation projects and trust that the funding would be available, changing times have forced them look for creative options to help them balance their yearly budgets and maximize the life of their existing pavements.
“You need to know your clients and know their needs so you can help them sell their projects and increase the odds of obtaining the necessary funding. You need to know how they budget. How they prefer to handle construction,” said Rich Thuma, project manager, Crawford, Murphy & Tilly.
At Washington Dulles International Airport, Thuma is part of a team that focuses on introducing more analyses into the pavement planning process. When the airport is evaluating the next 10 years of pavement projects, their goal is to improve the accuracy of cost estimates and the effectiveness of repair methods.
They begin by analyzing the PCI data, which will tell them how many cracks exist in a specific area of pavement. But they then take it a step further by asking why those cracks are occurring at that specific location, and then investigating until they have an answer.
“We can take the PCI data and tell you which pavements need extra testing. It’s still a network-level approach, but with a focus on particular pavements. It allows us to arrive at the optimal repair method that’s strategically targeted to a specific segment of pavement,” Thuma said.
Their next step is to deploy their extensive practical experience working on the Dulles pavements. They consider how the repair will need to be designed and constructed.
“This doesn’t mean you need to do all of the pre-engineering work in the planning phase, but you are able to identify where potential problems or conflicts may lie. So, you’re talking a little extra cost upfront, but the return will be there when it comes time to design the project,” Thuma said.
Just as relying on PCI data alone won’t tell you the complete story of a pavement feature, relying exclusively on a computer program to budget future projects will also leave an airport director susceptible to surprises. These programs typically calculate project costs based on the PCI rating and the square footage of the pavement in need of repair.
“It’s purely parametric. There’s no knowledge of what’s actually going on with the pavement and what’s actually going on at the airport. It’s basically a math exercise. But you can get much better estimates and can control those costs when you enter some design and construction insight into the equation,” Thuma said.
Practical pavement management is an integrated approach that does not focus exclusively on the pavement itself. The preparation of a PMP should not be isolated from the realities that exist on the airfield. It requires having a thorough understanding of the many factors that affect a repair project.
“If we know that an airport has funding constraints, that’s factored into the program right from the beginning. If we know they can only close one runway at a time, the implications of that are written into the PMP,” Taylor said.
Certain questions need to be asked: What are the airport’s priorities and concerns, in addition to repairing pavements? How will FAA geometric requirements and other regulations come into play? Who are all of the stakeholders and what are their expectations? These are questions that design firms know to ask at the onset of a project, but the answers are invaluable to airport management during the development of their PMP.
“Most of the cost and schedule overruns that a project runs into are attributed to ‘unknowns.’ Well, they aren’t really a mystery, it’s just that people who put together the PMP didn’t know to take them into account. Because that’s not their world. That’s where designers live, and that’s the perspective that a design firm that also does pavement management can bring to the table,” Taylor said.
A Practical Case in St. Louis
The happy ending to Lambert-St. Louis International Airport’s Runway 12R-30L project was a savings of $23 million. The story behind it is a case study in practical pavement management.
The overall PCI rating indicated that the runway was a candidate for complete reconstruction, at a cost estimated to be $80 million. In addition to the challenge of securing the funding for the project, the magnitude of this work had the potential of creating a domino effect on the Airport’s airfield CIP by displacing other priority pavement reconstructions in the program.
“We broke down the current and historical PCI data and found that the distribution of the distress along the runway was highly variable and that there were substantial portions of the runway pavement that were still in good condition. So, we knew that we needed to take a closer look and see what are the options were in order to create value, rather than just mark it down for complete reconstruction,” Taylor said.
They determined that a strategic rehabilitation approach would be the solution to their problem. Additional pavement testing revealed that the majority of the underlying structure of the pavement could last another 20 years. Therefore, the rehabilitation efforts focused on strategic repairs on sections where it was needed, along with a plan to manage surface distress on an ongoing basis.
“The people who developed the pavement management plan at Lambert have also designed pavements there and are very familiar with the airfield. You’re going to find a lot of that insight built into the airport’s plan. You’re going to see that things like cost and phasing and operations have already been factored in. That is a very valuable resource to airport management,” Taylor said
Practical Pavement Management
It should be noted that the practical pavement management approach is applied selectively at airports where it has been implemented. If an airport has 250 pavement features, it may only be applicable to 20 of them. Those 20, however, are typically operationally-critical pavements or high-dollar repairs on which significant benefits can be realized.
“We do our best work in that time period after the data comes in, but before you’re ready to start designing individual projects. That little bit of extra work upfront provides better cost estimates, less operational impacts and increases the overall value of the report,” Taylor said.
Roger Austin, AICP, ENV-SP is Vice President and Director of Marketing for Crawford, Murphy & Tilly, Inc. He has a background in aviation and previously served as CMT’s Aviation Planning Group Manager. He can be reached at [email protected].
