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Introduction:
Highways often have elevated asphalt medians, where the edge of the surface is higher than the middle. In a diagonal direction, this slope is called the camber. The camber of the road surface is made so that rainwater flows away from the edges. The camber of a road surface is the slope in the transverse direction that helps drain rainwater. It’s also called a road’s cross-slope.

Camber is a slope on the road surface in the transverse direction that allows rainwater to drain off the surface and keeps cars from sliding and causing damage to the pavement. Again, camber is one of the most important parts of a road’s pavement. It has a lot of benefits that make the road surface last longer.
Generally, a camber is a crown-shaped part of the road surface that is made by raising the middle of the road compared to its edges. Most of the time, the rate of camber or cross slope of a road is written as “1 in n,” which means that the transverse slope is in the ratio of 1 vertical to n horizontal, or it can be written as a percentage. For example, a road with 2.5% camber has a camber of 1 in 40.

• To keep water from seeping through the pavement and into the subgrade below, this can cause significant damage to the road surface. The road surface can severely damage if water soaks through the soil and settles.
• If the pavement surface is wet, it is less likely that cars won’t slip, making it unsafe for cars to drive on. It highlights the significance of having a camber that efficiently drains water from the road surface.
• To keep water from getting into the bituminous surface of the pavement. Water that stays in contact with the bituminous surface for a long time loosens the aggregate particles and causes the pavement layer to break down.

1. Sloped or Straight Camber:

Fig1: Sloped and Straight Camber
Courtesy: civilengineeringnotes.com
Straight Line Camber comprises two slopes that come from the edges and meet in the middle of the carriageway. It’s the simplest type of camber. It’s easy to build and easy to keep in good shape.

2. Composite Camber.

Fig2: Composite Camber
Courtesy: civiljungle.com
Hybrid camber could be part parabola and part straight line, or it could be made up of two straight lines with different slopes. Most of the time, the middle of the road is made to be parabolic, and the edges are given straight slopes. It helps to lessen the force of the pressure by making the wheel’s contact area bigger.

3. Parabolic or Barrel Camber:

Fig3: Parabolic Camber
Courtesy: dreamcivil.com
It is a continuous elliptical or parabolic curve. It provides a level roadway in the center and gradually rises to a steeper grade on the road’s periphery. Greater drainage efficiency results from the sharper edges of this camber type. Faster vehicles prefer this camber, so it is recommended for city streets. Maintaining and building a camber like this is challenging. Barrel camber is less user-friendly due to its sharper corners. Also, extra curbs are needed because the sharper the edge, the faster it will be damaged if it is not protected.

4. Two Straight Line Camber:

Fig4: Two Straight Line Camber
Courtesy: civilnoteppt.com
The straight lines are more acute at the edges and more gradual at the crown. It has been determined that this camber is optimal for use on Indian roadways.

Technique for Creating Camber in Roads:
Camber is typically provided on straight roads by elevating the center of the carriageway relative to the edges, creating a crown or highest point on the center line. If you want to improve surface drainage at horizontal curves with super elevation, you can do so by elevating the outer edge of the pavement relative to the inner edge.

Camber, also known as cross slope, is typically specified as a rate of 1 in n, with the transverse slope corresponding to a 1:n vertical to horizontal incline. The value of camber can be expressed as a percentage. The cross slope is proportional to the camber, so if the camber is n percent, the cross slope is n over 100.

• Water doesn’t pool up in the cracks and depressions on the road surface, which would be bad for the road and the people who use it.
• The camber makes rainwater runoff quickly, so water can’t soak into the foundations of this road structure and weaken them.
• The pavement acts as a barrier, keeping surface water from getting into the soil below.
• Water shouldn’t get into the layers of asphalt on the pavement.
• The rainwater should be drained off the pavement as soon as possible, then left to dry after it rains.

• It narrows the road because everyone will try to move in the middle.
• The edges of the road will get worn down over time.
• During the trip, the people on board feel unbalanced and uncomfortable.
• There will be more chances of accidents.

IRC Recommended Values of Camber in Road for Different Types of Road
Surfaces:

 Type of Road Surface Range of Camber in Areas of Low Rainfall Heavy Rainfall Cement concrete and thick bituminous surface 1 in 60 or 1.7% 1 in 50 or 2.0% Water bound macadam and gravel pavement 1 in 40 or 2.5% 1 in 33 or 3.0% Thin bituminous surface 1 in 50 or 2.0% 1 in 40 or 2.5% Earth Road 1 in 33 or 3.0% 1 in 25 or 4.0%

Conclusion:
Camber is a curve that is added to a road’s cross-section. It is the difference in height between the crown, the highest point of the road, and the edge. The crown is usually in the middle of the carriageway. The function of the camber is to get rainwater off the edges of the road surface. Camber is the slope given to the road surface in a crosswise direction so that rainwater can drain off the road.

References:
1. Sautya, M. (2017, September 16). 4 Types Of Camber || Road Camber Types – CivilNotePpt. In 4 Types of Camber || Road Camber Types – CivilNotePpt. https://civilnoteppt.com/4-types-of-camber/
2. Steffen, J. (2021, September 5). Types of Camber in Road | Cross Slope in Road | Camber Advantages | Camber Methods – ConstructUpdate.com. In ConstructUpdate.com. https://www.constructupdate.com/types-of-camber-in-road/
4. Highway Planning: Camber. (n.d.). In BrainKart. https://www.brainkart.com/article/Highway-Planning–Camber_3866/
5. Camber / Cross- Slope & Width of Pavement Or Carriageway. (2021, June 2). In ESE NOTES. https://esenotes.com/cross-slope-camber-and-width-of-pavement-or-carriageway/