Gradient of Road in Construction
This measurement of an upward or downward slope along a roadway is called Gradient of Road. It is, therefore, the slope imposed by the alignment along with the formation level of the highway. Generalized 1 in n means 1 represents vertical units and n represents horizontal units.
Types of Gradient of Road
A floating gradient is a gradient the motor vehicle descends at the same rate without applying power or brakes at any point during the descent.
In terms of drainage from the surface of a building, the minimum desirable slope calls a minimum gradient. In places with poor drainage, it is usually adopted.
It is possible to use a limiting gradient if the ruling gradient cannot apply. Hills and rolling terrain are usually suitable for it.
Depending on the topography of the location, it is necessary to adopt the steeper gradient. That is also the name given to the maximum gradient.
As the road alignment decides, the gradient usually adopts as the ruling gradient. Roads designs using a ruling gradient as it provides maximum safety while minimizing costs.
It is known as the exceptional gradient when the slope exceeds the limiting slope. The use of this gradient is limited to rare instances where roads are short. The use of exceptional gradients is often unavoidable in places like mountainous terrain.
However, a gradient with an exceptional slope leads to higher fuel consumption and friction losses.
An average gradient is a ratio between the amount of rising or fall between two points along the alignment of a road divided by the distance between the two points.
Purpose of Gradient of Road
- It is necessary to connect two stations of different levels with each other.
- Especially when the pavement has curbs, it is important to provide effective drainage of rainwater.
- Obtaining adequate drainage in a cost-effective manner.
- In order to achieve economic road construction, cutting and filling should be balanced.
Functions of Gradient of Road
When it comes to building roads, the gradient is the most important factor. During alignment, the road must have a proper gradient to keep it horizontally aligned.
The Gradients allow vehicles to move smoothly on vertical curves. The Gradients also prevent rainwater from pooling on the surface of roads.
When the terrain is flat and curved, gradients solve drainage problems on curved roads. Besides considering the cost of construction, vehicle operation, and possible practical problems on the site before determining the road's gradient, it is necessary to consider the cost of construction, vehicle operation, and potential difficulties on the site before making a final decision.
Gradient of Road Effects
Gradients have a considerable impact on vehicle speeds. It is especially crucial on roads where the percentage of heavy vehicles is high. Since these heavy vehicles have less sight distance when traveling uphill, they generally control traffic speed.
In turn, operating costs for the vehicles increase, and road capacity decreases. Accidents increase in the gradients when heavy vehicles and light vehicles are traveling at high speeds.
Some Key Factors of Gradient of Road
- Ground nature.
- Drainage is necessary.
- Traffic nature.
- Surfaces used on roads.
- Coverage of the entire height.
- Interaction between roads and railways.
- It is necessary to maintain safety.
- An approach to the bridge.
To get more details, watch the following video tutorial.
Video Source: Engineer's Coach