Before airport runways looked the way they do today, they consisted purely of a strip of cleared land with sand, grass, gravel, salt or ice. As you can imagine, the planes in those days didn’t have nearly as much wheel-to-runway grip and safety as they do now. Whilst some smaller airports still use these raw materials for their runways, most are now made using asphalt.
Although they didn’t look nearly as sophisticated back then as they do now, each runway was carefully placed and designed depending on the area’s wind direction and speed – as is still the case today.
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What is aquaplaning and hydroplaning?
The term ‘aquaplaning’ or ‘hydroplaning’ refers to the situation where there’s too much water on the landing surface, which reduces traction and grip, creating the ultimate skidding risk. Even a thin layer of water can cause hydroplaning if the tire in motion is unable to penetrate the water layer and grip onto the surface.
In some cases where there’s too much water on the runway, the plane might not be able to land. This is because in order to land safely, the aircraft wheels need to make contact with – and grip onto – the runway, without skidding. Without the proper grip, the aircraft could overrun the runway and crash into the end of it.
The risk of hydroplaning depends on a few factors. A few examples include the runway material used, the tire tread pattern and depth, and the aircraft’s speed. The high speed at which aircraft tires hit the runway in general makes it extra important that the right measures are in place when placing airport runways, ensuring they are as drained, dry and grippy as possible.
Why is asphalt used to create modern-day runways?
Today, asphalt is by far the most commonly used material to create runways. This is because asphalt is an extremely durable material that can be put under immense weight and pressure, with little to no damage. Asphalt is also an extremely affordable material, which is also generally cheap to install, and can last up to a decade or longer before needing to be replaced or repaired.
Asphalt surfaces can also withstand heavy weather conditions, as long as they are structurally sound. Another bonus – a very important one – is that asphalt creates the optimal environment to ensure good wheel-to-road traction and grip.
To prolong the life of asphalt, you’ll need proper draining in place, which runway grooves naturally do a great job at. The shape of the runway grooves direct water away from the asphalt, helping to prevent water from flooding or building up below the asphalt layer. If water does flood or penetrate the asphalt layer, it could lead to serious structural damage.
What are runway grooves and what are they used for?
To increase and ensure the best chance of a safe landing, runway grooves are sometimes added to runways. Runway grooves are put in place to add grip and help excess water escape from the runway, therefore minimising the chances of hydroplaning.
Essentially, one can think of these grooves in the same way you might think of the tread on a tire. In fact, runway grooves are so efficient in preventing hydroplaning that even tires without tread could land on a runway that has them.
Not all modern runways make use of grooving, but this is quickly changing, as more and more people are seeing just how invaluable they are. As asphalt and runway grooves work so well together, they are rapidly becoming the golden standard.
How are runway grooves created?
These grooves are cut into the asphalt surface using machines, in a way which creates diamond or square shapes. These cuts are created in a transverse direction to that of the direction in which the vehicle will be moving in.
Adding runway grooves to asphalt is often a lot cheaper than doing so with concrete, because asphalt is softer than concrete and therefore, easier to cut into.
Are runway grooves useful on a dry runway surface?
Runway grooves are just as beneficial to have on dry surfaces as they are on wet surfaces. On a dry surface, they have the ability to reduce or shorten braking and stopping distances, through what’s known as ‘tire tread interlock.’ Not only is this safer for everyone onboard, but it might also mean that less space is required when building the runway itself.
What’s the difference between traditional and trapezoidal grooving?
The main difference between these two runway groove patterns is their spacing and the shape in which they are cut. Traditional grooves are cut using a square blade, whereas trapezoidal blades create diamond shapes.
The type of runway groove pattern that is used depends on the environment and unique situation at hand. Both traditional and trapezoidal grooving patterns remain highly effective at draining away water and improving traction and grip.
