In this article, we will discuss
Definition of Cross-Slope | 4 types of cambers or cross slope | Camber-Providing Method | cross-slope calculation formula | Methods for Slope Calculation
Definition of Cross-Slope
The slope that is provided to the road surface in the transverse direction to drain rainwater from the road surface is known as a cross slope or camber. Because of the following factors, providing a cross slope for water drainage and quick disposal from the pavement surface is important.
What is Cross Slope
Camber, cross fall, or cross slope are terms used to describe the convexity provided to the road surface in the transverse direction to drain off rainwater.
Camber is typically provided on straight roads by raising the center of the carriageway concerning the edges.
Most of the time, 1 in n is used to describe the rate of camber (vertical: horizontal). It can also be shown as a percent.
There are 4 types of cambers or cross slope:
- Composite camber.
- Sloped or Straight camber.
- Two straight line camber.
- Barrel camber.
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Composite camber.
It has two straight slopes coming from the edges and a circular or parabolic crown.
Sloped or Straight camber.
It is made up of two straight slopes that go from the sides to the middle of the road. This type of camber is easy to make and doesn't require much skill.
Two straight line camber.
This type of camber is considered the best for Indian roads because it has two straight lines that are steeper near the edges and flatter near the crown.
Barrel camber.
It is made up of an elliptical or parabolic curve that goes on forever. This camber is best for roads where cars and trucks go fast.
Camber-Providing Method:
The subgrade is given the required camber. Templates or camber boards are made with the desired amount and shape of camber to provide the subgrade with the camber it needs. Material for the subgrade is spread out and pushed by hand into the shape of the camber.The rolling is then started at the edge and works its way toward the middle. Then, the top surface is checked with the help of templates or camber boards. The lack is spreading the material or taking it away as needed.
The cross-slope calculation formula
For a pavement of width W and cross slope 1 in n, a=nW/2.y = 2.X^2 / NW
Example:
Two types of road pavement will be built in an area that gets a lot of rain.(a) State Highway has two lanes, a bituminous concrete surface, and (b) a Major district road with WBM pavement and a width of 3.8 meters.
If the camber is straight, what should the height of the crown be in relation to the edges in these two cases?
Solution:
Camber of the straight-line type has been suggested.(a) For SH, the width of the two-lane road is 8.0 m.
For a surface made of bitumen concrete in a place where it rains a lot, make sure the cross slope is 1 in 50. Rise of a crown concerning edges = 8/2 * 1/50 = 0.08m.
(b) For a WBM road in an area with a lot of rain, ensure the cross slope is 1 in 33 or 3%.
Rise of the crown about edges on a 3.8-meter-wide pavement
= ( 3.8 x 1 ) / ( 2 x 33 ) = 0.058 m
What is the difference between cross slope and super-elevation?
Usually, a road surface slopes in two directions: longitudinally, in the direction of the centerline of the road, and transversely, at right angles to the centerline of the road. This post talks about the transverse slope of a road. Several different words are used to describe the transverse slope. These include camber, cross fall, superelevation, cant, and cross slope.Camber
Camber is the transverse convexity applied to a carriageway or footway's surface.
Cross-Slope
Crossfall (or cross slope) is the slope of any portion of the carriageway measured at a right angle to the alignment.
Superelevation
The continuous transverse slope typically applied to a carriageway at horizontal curves is known as superelevation.
The terms all essentially refer to the same thing. In one instance, superelevation, cant, and cross-fall are all mentioned in the same sentence. The cross-fall can be designed to fall from the edge of a carriageway to the center median, to vary with each lane across the width of one carriageway on a dual carriageway road, or to vary continuously with the road surface taking the shape of a parabolic curve, depending on which standard you look at.
Therefore, the minimum values, maximum values, and direction of the cross fall are three sub-aspects of cross fall that could be examined. The rest of this article examines minimum cross-fall.
Recommended values of camber or Cross-Slope
A range of values is provided so that a flatter camber can be adopted in areas with low rainfall, and in areas with high rainfall, a steeper camber can be utilized.
The recommended cross slope for the carriageway, paved shoulders, and edge strip of expressways with bituminous and cement concrete surfaces is 2.5% in regions with annual precipitation exceeding 1000 mm and 2.0% in areas with less than 1000 mm of rainfall.
Method's for Slope Calculation
1. How to Calculate a Slope Gradient
2. How to Calculate the Slope Percentage
3. How to Calculate Slope in Degrees
