Parallel Runways or Intersecting?: Evolution of Airport Design

Chicago O’Hare Airport is the 4th busiest airport in the world by passenger traffic. Over the years, the airport has added runways catering to the ever-growing passenger demand. While the 2003 airfield layout comprises of 6 runways, the number has grown to 8 in 2021. But there is one more shift – the airport is moving towards parallel runways.

parallel runways and intersecting runways at Chicago O'Hare Airport
Chicago O’Hare International Airport Airfield Layout over the years. Credits:

Are you wondering why? Read on.


The Winds of Change

In the early days of commercial aviation, the skies were ruled by small propeller-driven aircraft. These planes were highly sensitive to wind direction and speed, making crosswinds a significant concern. Pilots preferred taking off and landing into or opposite to the wind for safety. To facilitate this, many airports planned intersecting runways, offering flexibility in choosing runway directions based on wind conditions.

Credits: Ilan Bruner

While they served their purpose, simultaneous operations on intersecting runways proved risky. Several airports worldwide, including Perth, Moscow, Brussels, Zurich, Birmingham, and Chicago, witnessed safety incidents attributed to intersecting runways operating concurrently. These incidents raised concerns about the safety of this runway configuration.


A Modern Shift in Runway Design

In modern aviation, intersecting runways are no longer the preferred choice, though they still exist at some airports. The shift in design philosophy can be attributed to the evolution of aircraft technology. Larger, more powerful jet airliners made crosswinds less formidable. This shift led to a prevailing practice in modern airport architecture – parallel runways.

Modern airliners are bigger and more powerful, making them less dependent on wind patterns for optimum operations. Credits: Yuga

Parallel runways are now a common sight at the world’s busiest airports, with approximately 8 out of the 10 busiest adopting this layout.

There are several compelling reasons driving this shift in airport design philosophy:

1. Enhanced Safety: Parallel runways minimize the risk of runway incursions, which have become a significant concern in contemporary aviation

2. Streamlined Operations: They enable better control of aircraft movements, even in complex traffic scenarios, vital for managing congested skies

3. Optimized Land Utilization: In the face of space constraints, parallel runways make efficient use of available land, maximizing airport capacity

4. Improved Approachability: They offer better runway approachability for takeoffs and landings, leading to shorter turnaround times for airlines, crucial for maintaining flight schedules

Interested in what else drives airline efficiencies? Read on here.

As aviation and airport design continue to evolve, parallel runways have emerged as the safer and more efficient choice for modern airports. They ensure smoother and safer journeys for passengers worldwide while addressing the changing needs and challenges of the aviation industry.

Cover credits: Lucash

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