Runway rehabilitation: A hybrid solution to keep airports profitable

Runways are an airport’s most critical and largest facilities, so it’s vital to keep them in peak shape. Several possible maintenance solutions exist: minor spot repairs, larger-scale works, and complete runway rehabilitation. But after many years’ use, rehabilitation may be necessary and usually entails major works requiring a long and costly demolition phase. But what do you do when one of the country’s longest runways needs a major facelift—quickly and affordably? Fortunately, the extensive rehabilitation of Montreal–Mirabel International Airport’s runway (an impressive 3,658 metres or 12,000 feet long) resulted in a new hybrid project that meets the client’s specific needs in terms of time, budget, and ecological footprint, while minimizing disruptions and constraints to the airport’s normal activities. Here’s how it works.

The right solution for an optimal design
As one of the world’s top three aerospace hubs, Montreal–Mirabel is home to nearly 30 businesses, whose activities—from construction to airplane maintenance—depend on the site’s facilities. After 40 years’ service, the main runway was due for a major facelift. We needed to come up with a plan that would meet the highest standards in airport design, yet allow Aéroports de Montréal (ADM) to get back to the airport’s usual activities as quickly as possible.

We began by assessing the runway’s condition. Using a precise surveying method involving laser remote sensing, and incorporating findings from a wide range of geotechnical studies, we obtained a detailed portrait that helped define feasible rehabilitation options. What emerged from this process was a new hybrid concept consisting of various work zones and limiting demolition to specific sections of the runway. We completely rebuilt the runway’s thresholds, without touching existing aircraft arresting systems used by military aircrafts, and carried out a whitetopping on the runway’s middle section after repairing the most damaged existing slabs. Runway sides were filled with materials recycled from the two thresholds, to limit the project’s ecological footprint.

Though ideal, this hybrid concept brought with it a number of challenges. We first had to set design parameters that would ensure a proper transition from one zone to the next. Given the projected traffic and extreme temperature differences for the region (from 30 degrees Celsius in summer, down to minus 30 degrees Celsius in winter), it was also necessary to ensure that the zones would behave exactly the same way in the short, medium, and long terms, to prevent differences in the levels of the various zones.

Considering a runway rehabilitation project in its entirety is essential; various factors like budgets, runway conditions, daily airport operations, and geographic context, influence how design decisions are taken to adapt to each runway’s unique situation. In the case of Montreal–Mirabel, we showed that it is possible to combine several rehabilitation solutions within the same project, by thoroughly understanding current runway conditions, so as to optimize project costs, respect deadlines, and meet clients’ expectations.