DALLAS – The professionals who design airport runways examine many details to maintain safety, efficiency and awareness of the surrounding environment. What can these experts achieve by upholding precision in everything they do? 

Increasing Capacity While Accommodating Modern Air Travel

Many runway design decisions center on maximizing capacity and keeping the airport relevant and able to meet current and future needs. Until relatively recently, a popular choice was to create intersecting runways. Then, pilots could take off or land opposite the wind direction, which they preferred to do for safety when operating small, propeller-based planes that were highly subject to crosswinds.

Although intersecting runways made those parts of air travel safer, they created complications elsewhere, particularly as traffic levels increased. These designs made it challenging to coordinate movements between the planes, and accidents occurred. However, since today’s planes are larger and less affected by crosswinds, parallel designs have become more popular. Estimates suggest approximately eight in 10 of the busiest airports feature them. 

Besides being safer than their counterparts, parallel designs make coordinating activities easier for air traffic professionals. They also make excellent use of airport land, raising capacity. However, some designers choose less common layouts for their runways, believing they can also effectively address capacity needs. 

For example, Colorado’s Denver International Airport (DEN) has its runways in a pinwheel shape — comprising four parallel north-south runways and two east-west ones. Officials said this accommodates high air traffic levels while maintaining efficiency. However, a local influence also affected designers’ choices. The north-south designs cater to the area’s predominant wind patterns, but the other two are most useful during strong crosswinds. 

However, professionals coordinating takeoff and landing activities at the Denver airport also evaluate factors such as which runways will give planes the shortest taxi distances. Planning those details keeps air traffic operating smoothly, even during particularly busy periods. 

Addressing Current, Future Ground Stability Needs 

People designing airport runways must also analyze the ground underneath the concrete slabs, ensuring it can withstand massive weight and heavy ongoing use without compromising safety or causing erosion. Well-stabilized runways are less prone to potholes. Those issues pose dangers and make the surface temporarily unusable while repairs occur. 

Checking stability also involves building up the runway’s shoulders, preparing them in case planes veer to one side when they land, take off or taxi. In addition to focusing on the parts of the runway that receive the most traffic, designers must plan for those rare but possible instances.

Soil nailing is a widely used technique to improve ground stability. It involves using high-tensile-strength materials, such as solid steel bars, to reinforce the earth. Their  corrosion-resistant nature also helps to improve durability. Any runways with a slope could benefit from the extra stability depending on their steepness. Strategically placed slopes are common, slanting down at the ends to help departing planes gain momentum or curving up to slow them as they land. 

Another factor to consider is location. Airports in areas at risk for flooding or excessive rainfall could use these materials to mitigate risks from flooding. Designers should review past weather and site data to determine whether those problems have caused previous issues. 

Staying Mindful of Sustainability

Sustainable operations are a top priority for many airport officials, and their concerns include designing runways for the future without generating excessive waste. One example comes from Indianapolis International Airport, where people needed to replace the surface of an existing runway and taxiway. 

Those involved broke the project into three phases, carefully determining when to work on each section. They needed to figure out how to keep the project on schedule while causing the least disruption. In addition to the commercial air travel activity handled by the airport, this location is one of the biggest hubs for an international logistics company. 

Sustainability came into play when people put 135,000 cubic yards of the previous runway’s surface into the new project’s base material. Besides that substantial recycling effort, the team also reused more than 4 million gallons of water, relying on ponds and hydrants. The former was particularly beneficial after heavy rains.

Another sustainable plan was to inject the concrete with a carbon-capture technology. The injection phase went as intended, but the pouring stage of the surface replacement ended before the company handling it could reduce the cement content.

Outside of this project, being sustainable also extends to ensuring current work will remain reliable for years to come. One way is to design airport runways to include long-life pavements. Regardless of whether those projects feature recycled materials, at least the surfaces should hold up to ongoing use, making them sustainable over time. Since planes account for more than a quarter of the world’s emissions, prioritizing sustainability through thoughtful runway designs is important. 

Understanding Runways’ Maintenance and Repair Needs

Those who design airport runways must also make them as user-friendly as possible for teams who want to keep them in good condition without significantly reducing overall activity. For example, asphalt is relatively easy to maintain, and the associated activities can occur without major disruptions. However, gravel runways require periodic partial rebuilds, which are more extensive. Some designers include surface treatments to simplify maintenance while extending overall life spans

Although some airport officials plan maintenance based on general life span expectations, it is more common for them to tackle issues when they arise. Staying on top of those matters requires several daily checks and teaching workers to spot signs of trouble.

Most runways last eight to 12 years, but the specifics vary depending on aircraft weight and usage frequency. Additionally, particular issues can occur as surfaces reach the end of their life spans. For example, stones and chips come off tarmac surfaces with age. In the worst-case scenarios, they can require planes to undergo US$12 million engine replacements if the materials get caught inside the plane’s mechanical system.

The United Kingdom’s Elstree Aerodrome has never replaced its runway, and some think it’s because it accommodates helicopters rather than large planes. The reduced weight minimizes runway stress, likely making maintenance less extensive. 

Runway designers should have in-depth discussions with those making the final decisions about construction, longevity and other matters that will impact maintenance. Explaining the pros and cons of different surfaces can help leaders select the options best aligned with their requirements and preferences. 

Upholding Best Practices to Design Airport Runways

These examples highlight why runway designers must examine numerous aspects to get safe, purpose-built results. Aiming for well-established ideas while remaining open to newer surface treatments, materials and other opportunities will help teams reach desired outcomes.