What is the Camber of a Road and Why Does It Matter?

When you are running at the edge of a road (or along a grassy hill or on a beach, for that matter) you may sometimes notice that the road isn’t exactly flat. The reason for that is because most roads have a camber to them that helps water drain off of them rather than pooling up in the center of the road.

The camber is any curve on a surface, and in this case refers to upward curve from the edge of a road towards the center.

The more severe the camber to the road, the easier it is to roll an ankle or to develop a muscle imbalance.

When a road is steeply cambered, you may find that one leg is at a slightly lower elevation than your other leg, which can throw your stride off.

The leg that is closer to the center of the road will feel like it is a “longer” leg than the other to your body, so your body will compensate through the way that it bends at the knee, how much your foot flattens on impact, and how much your leg rotates inward as you are running. This can lead to knee or hip soreness.

If you do find yourself running on steeply cambered terrain, try running on different terrain or different routes if you can. If you have to run on the same streets, try running them in the other direction (if local laws allow) or by running at the edge of the road on the shoulder rather than on the road itself. Icing and self-massage will also help the soreness go away

Camber & its types

We have seen almost all highways being raised in the middle portion of the road surface with respect to the edges. This cross slope in the transverse direction is called as the Camber (or Cant). It is generally provided with the sole purpose of draining the rain water from the road surface towards the edges.

Other objectives of providing camber are:

• Protection of the road surface, especially for gravel and bituminous roads by draining the unwanted water as quickly as possible.
• Protection of the subgrade by providing good drainage conditions.
• For safety considerations, as wet pavement conditions are quite undesirable from safe driving point of view.

The cross-section shape of the transverse or cross slope can be curved, straight or a combination of both. The central part of the road which is raised is called the crown.

The cross slopes can be expressed in slope as 1 in n or in percentages as n% (for example, 1 in 50 or 2%). The design values of cambers mainly depend upon the type of the pavement and also on the average amount of the rainfall in the area. Steep cambers are effective in quick removal of surface water but are undesirable as they will erode the surface. Generally, cambers of slope 2 to 3% are provided. On straight sections of roads, shoulders are provided with higher cross fall than that of the carriageway by 0.5%.

Values of cambers depending upon the type of pavement
Pavement type	Cement concrete	Bituminous	Gravelled	Earthen
Camber, %	1.5 to 2%	2 to 3 %	4%	5%

Excessive camber should not be provided unnecessarily because of the following reasons:

• Due to steep cross slope, most of the vehicles will have the tendency to move along the centre line of the road, thus affecting the road capacity.
• Major accidents can be caused due to instability of highly loaded vehicles.
• The edges will wear out faster than the central part.
• Cross rots are formed.

Types of camber

There are generally three types of cambers provided along the road surface, namely straight line, parabolic and composite cambers.

Straight line camber

These are provided with two equal uniform straight line slopes at both sides of the crown and are also known as Plane cross slopes. They are generally adopted for very flat slopes such as PCC or RCC Pavement.

Parabolic Camber

In parabolic camber, the cross slope is in the shape of simple quadratic parabola. In this case, the ordinate Y varies as the square of abscissa X (simple parabola equation).

Parabolic cambers are designed for fast moving highways. A favorable condition for overtaking operation is provided due to the curved cross slope. As the slope increases outward to the road edge, the flow of surface water away from the pavement is enhanced. One disadvantage of parabolic cambers is that they are very difficult to construct.

Composite camber

Composite camber may be composed of partly parabola and partly straight line or two straight lines having different slopes. Generally central part of the road is made parabolic and provided with straight slopes near edges. This helps to decrease in intensity of pressure by increasing the contact area of the wheel.

Camber is

1. To curve upward in the middle.
2. to arch slightly.

Road Camber height depends upon

1. Rainfall intensity in the area.
2. Type of the road surface whether it is flexible or rigid.
3. In case of flexible pavement, the recommended height of camber is 2 %. of the total width of the pavement.
4. For rigid pavement, the maximum recommended width is 1:72.

Drawback of providing excessive road camber height

1. It reduces the road width as everyone will try to move on the middle of the road.
2. Chances of accidents will increase.
3. The passengers feel unbalance and discomfort during journey.
4. The road will wear and tear on the edges.