Camber / Cross- Slope:

Note: This topic is part of the second chapter of Highway Engineering. I suggest reading this topic in the context of the complete chapter: Geometric Design of Highway. If you want to read the entire Highway Engineering, click here: Highway Engineering.

• It is the slope provide to the road surface in the transverse direction to drain the rainwater from the road surface to avoid the following:
  1. Stripping of bitumen from the aggregate in the presence of the water.
  2. In order to avoid swelling of sub grade in case water seeps up to it.
  3. The slipping of the vehicle over the wet pavement.
  4. Glare over the wet pavement surface.
• On straight Road it is provide by raising the center of carriage way with respect to edges forming the crown on the highest point along the center line.
• At horizontal curve with super elevation, the surface drainage is provided by raising the outer edge.

• It is represented in any of the following ways:
  1. As percentage :For example cross-section 5% ⇒ tanθ = \(\frac{5}{100}\).
  2. As fraction : For example cross- section = 1 in 20 = \(\frac{1}{20}\) = 0.05.

• The value of cross-section depend on following factor:
  1. Type a pavement surface
  2. Amount of rainfall

Type of Cross- Slope / Camber 

1. Straight line Cαmber

2. Parabolic Cαmber

3. Composite Cαmber

Note: For cement concrete pavement straight line camber is preferred. As it is easier to lay.

Gradient = 2x Cαmber

Width of Pavement or Carriageway:

• Width of payment depends upon width of traffic, lane and number of lanes.
• Width of traffic lane is decided on the basic the type of vehicle moving on it, along with same clearance in both the sides.
• Passenger car is considered as a standard vehicle to decide the width of carriageways. (Width of passenger car = 2.44 meter= 2.5 meter)
• For rural highway, if pavement has two or more lane, width of single lane is 3.5 meter.
• The number of lane to be provided depends upon traffic volume.
• The width of carriageway for different conditions are follow.

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