Why do highways have grooves

This results in asphalt crumbling and disintegrating resulting in dangerous potholes and a road that needs to be resurfaced. Newer engineering techniques allow concrete cutting to be done lengthwise instead of horizontally. These lengthwise grooves do a much better job at reducing the noise level produced by tires on concrete at high speeds. Reducing noise is one of the most common reasons that lengthwise grooves are cut into concrete.

Unlike asphalt, concrete is not poured to create a road surface but rather placed in large slabs. The edges of these slabs are prone to wear and tear and on some highways, tend to drift or slide. In order to prevent this from happening, the slabs are reinforced with steel bars. The grooves on the highway are designed to hold these steel reinforcements. Reinforcing a concrete highway can increase its lifespan by up to 10 years.

The reason that concrete is used on so many highways in the first place is because it more resilient and durable than asphalt. Although it may have some drawbacks, such as the noise factor, a longer-lasting road surface is preferable for highways that carry large amounts of traffic and heavy vehicles at high speeds.

This is also important to prevent potholes or crumbling at the edges of the road surface which result in hazardous driving conditions. According to an article in USA Today , the lines in concrete were first started as a solution to a problem NASA engineers needed when landing the space shuttle on a wet runway.

They discovered that cutting grooves into runways helps channel water away from the runway and significantly reduces accidents. Many highways and airports now have grooved pavement.

I spoke to Leah deRiel, senior project engineer for the City of Miramar , Florida — which uses lots of concrete for roads and receives lots of rain — about the effectiveness of these lines. MORE: Read more traffic issues driving people crazy. She tells me concrete can't even come close to absorbing all the rain produced even by a small thunderstorm. She says road crews are supposed to pour a concrete roadway so there is a high point in the center.

That slope allows the rainwater to flow to the side of the road. There's a point at which the water will flow like a sheet anyway if you have high enough water volume, so there is a point at which the groves don't really help much, but they're way better than nothing. Winds in a thunderstorm can generate more force on a car than these grooves, and drivers have a responsibility to maintain control of their vehicles at all times. Another reason for the long lines in the concrete, according to deRiel, is to help with pavement joint impact reduction.

This is why the grooves are cut longitudinally rather than transverse. In order to distribute load evenly, slabs are poured as close to square as practical. They're also poured to get the joints as close to lane lines as possible, to minimize the occurrence of your tires riding over a longitudinal joint all the way to your destination. If you're doing 5, feet of pavement, that's a lot of joints.

Imagine pouring, by hand, all of those slabs. What are the chances that they'll all be at exactly the same elevation? Copyright owned or licensed by Toronto Star Newspapers Limited.

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