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What is the Gradient of the Road and Types of Gradient of Road

The gradient of a road is crucial to the road’s very existence. The topography of most areas is not flat. Slopes are common on things that vary in scale. If a road were built there, there would likely be accidents. Road slopes facilitate these height fluctuations, which allow for smooth vehicle travel.

Different Types of Gradient of Roads
Fig: Different Types of Gradient of Roads

What Is the Gradient of Road?
A gradient is a rate at which a road goes up or down along its path. A road’s gradient rises or decreases with the road’s horizontal alignment. It’s the height difference between where you started and where you ended, expressed over the same length of time. Slopes and other undulations on the land’s surface are the norms rather than the exception. Errors may occur if a road is built there. The road’s gradient absorbs these fluctuations in altitude. To build highways, they must be included since they regulate the transitions between straight stretches. They answer problems like uneven terrain, flooding, high construction costs, and public discontent.

Purpose of Gradient of Roads:
Roads are built to connect two or more places, and the best way to build a road’s grade is to follow the land’s shape as closely as possible to avoid having to do a lot of cutting or filling. For example, in hilly areas, the slope of the road is designed and built to match the slope of the land, but efforts are made to meet the desired maximum slope. Because of this, most roads have 5% to 8% steeper grades.

In flat areas, like urban streets or highways, the road slopes are designed and built first to match the existing ground profile and then drain surface water with systems like pipe/gully or kerb drains. It’s important to remember that roads on completely flat land must have a minimum slope of 0.5% to drain properly.

Importance of Gradient of Roads:

Effects of Gradient of Roads:

The Factors for Selection of Gradient of Roads:

Types of Gradient of Roads:
1. Ruling Gradient:
The ruling gradient, also called the design gradient, is the steepest angle with which the vertical profile of the road can be made. It depends on the terrain, the inclined length, the speed, the vehicle’s pulling power, and whether or not there is a horizontal curve. If the land is flat, it might be possible to make the slopes flat, but if the land is hilly, it could be more cost-effective and sometimes even possible. The designer picks the rule-of-thumb gradient by using a certain speed as the design speed and a standard-sized vehicle for the design.

2. Exceptional Gradient:
The exceptional gradient is the gradient that is steeper than the limiting gradient. This slope is usually only used in special situations where the roads are shorter than usual. Exceptional gradients are steep gradients used in situations that can’t be avoided, like mountainous areas and terrain. But a steep slope has a downside: it uses more fuel and causes more friction losses.

3. Limiting gradient:
This gradient is used when the cost of the building goes up significantly with the standard gradient. On rolling land or land with hills, it may be necessary to use a limiting gradient. But the length of the steepest parts of the road should be limited, and they should be surrounded by straight roads or roads with less steep grades.

4. Floating Gradient:
A “floating gradient” is a slope where a car moving at a constant speed keeps going down at the same speed without the driver applying power or the brakes.

5. Average Gradient:
For any two places along the alignment, the average gradient is calculated by dividing the vertical difference between them by the horizontal separation. The initial paper location or primary survey benefits from knowing the average grade because it approximates the length of the proposed alignment.

6. Minimum Gradient:
When surface drainage is important, the minimum gradient is used. The side drainage will be taken care of by the camber. But the drainage along the side drains needs a slope so water can flow smoothly. So, there is a minimum slope for drainage, which depends on how much rain falls, the type of soil, and other site conditions. A minimum of 1 in 500 may be enough for concrete drains, and 1 in 200 works well for loose soil drains.

The road’s gradient is the rate at which it rises or falls along its length about its horizontal alignment. It’s the vertical distance traveled over the horizontal distance corresponding to it. Before deciding on the slopes, it’s important to consider how much it will cost to build, how much it will cost to run vehicles on the site, and any other practical issues. Most of the time, steep grades are avoided as much as possible because they are hard to climb and cost more to build.

1. GceLab. “What Is Road Gradient? 5 Important Points.” What Is Road Gradient? 5 Important Points, Accessed 30 Nov. 2022.
2. “Types of Gradient | Gradient in Highway Engineering.” Types of Gradient | Gradient in Highway Engineering, Accessed 30 Nov. 2022.
3. Steffen, John. “Gradient of Road | 6 Types of Gradient of Road | Effect of Gradient on Roads | Factors of Gradient of Road –”, 12 July 2022,
4. Facilitator, Constro. “Different Types of Gradients Used on Roads.” Constro Facilitator, 13 Oct. 2021,
5. “Road Gradient with Its Types for Highway Design?: An Overview.” Howtocivil, 10 Mar. 2021,
6. Sautya, Malay. “6 Types of Classification of Gradient – CivilNotePpt.” 6 Types of Classification of Gradient – CivilNotePpt, 16 Aug. 2022,

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Kanwarjot Singh

Kanwarjot Singh is the founder of Civil Engineering Portal, a leading civil engineering website which has been awarded as the best online publication by CIDC. He did his BE civil from Thapar University, Patiala and has been working on this website with his team of Civil Engineers.

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