Many of us focus only on visible issues like potholes, but roughness affects ride comfort, vehicle safety, and running costs in ways we often don’t realise.
BHPian Maddies@07 recently shared this with other enthusiasts:
We always worry about the potholes on the roads that we can easily notice, and they are a great danger to road safety. Yet another important hidden factor that is silently affecting every vehicle owner is road roughness.
What is road roughness?
Road roughness happens either because of mistakes or flaws during construction, or because the materials in the road shift and settle over time due to traffic. It refers to bumps and uneven spots on the road surface that aren’t perfectly flat. These uneven areas can affect how vehicles handle, how comfortable the ride feels, the forces acting on the vehicle, and even how water drains off the road. Roughness includes things like dips and bumps along the length of the road, across its width, and the slope across the road surface.
There is an extensive IRC guideline: IRC:SP:16-2019.
Importance of road roughness:
1. Road Safety
Bumpy roads make vehicles shake and can tire out drivers, increasing accident risks. A vehicle’s suspension affects how these bumps are felt. If bumps happen in a rhythm matching the vehicle’s natural movement, the ride may feel smoother, but if they’re out of sync, the shaking can get worse, making the car bounce so much that the wheels might even lose contact with the road. Rough roads also change how much grip the tyres have, making steering and braking harder, which can cause drivers to lose control—especially if each side of the vehicle hits different bumps, leading to uneven forces and safety risks.
2. Vehicle Operating Cost
Road roughness affects how much it costs to run a vehicle, including fuel, oil, tyre wear, repairs, and how quickly the vehicle loses value. Bumpy roads make vehicles burn more fuel and often force drivers to slow down. Drivers also tend to slow down on rough roads because it’s uncomfortable, which can affect how fuel-efficient the vehicle is. Overall, rough roads lead to higher costs for maintaining and operating vehicles.
3. Riding Comfort
Rough roads make driving uncomfortable by causing constant vibrations and jolts inside the vehicle. Passengers can feel every bump, which leads to fatigue, discomfort, and even motion sickness during longer journeys. Over time, frequent exposure to rough rides can cause physical strain, especially for drivers who spend many hours on the road. Good road smoothness ensures a quiet, steady ride, improving comfort and making travel less tiring for everyone in the vehicle.
4. Vehicle Speed
Road roughness affects how fast vehicles can travel safely. Drivers tend to slow down on bumpy roads to avoid damage to their vehicles and to maintain control. Rough surfaces make it harder to steer and increase braking distances, which forces drivers to reduce their speed. This slowdown affects travel time and can reduce the overall efficiency of transportation. Smoother roads allow vehicles to maintain steady speeds safely, helping traffic flow better and saving time for road users.
How is it measured?
It is measured as the Roughness Index (RI).
The pavement surface roughness is expressed as Unevenness or Roughness Index (in mm/km) and is measured using a Fifth Wheel Bump Integrator or a Car Axle Mounted Bump Integrator.
For all major road construction projects, making sure the road surface is even is a must during construction. This helps engineers ensure good quality work. To check this, a 3-metre straight edge is placed along the center of each lane to measure any bumps or dips. The road must follow the limits set by the Ministry of Road Transport and Highways in their official specifications (Section 902, Table 900-2). The allowed roughness levels, measured in millimetres or metres per kilometre, vary depending on the type of road. All new roads are expected to meet the standards for a “Good” surface condition. If a road falls under “Fair” or “Poor” condition, it means maintenance should be planned soon to prevent further damage.
And the reason I’m writing this is because I want fellow BHPians to understand the concept of road roughness and why it’s so important. Many of us focus only on visible issues like potholes, but roughness affects ride comfort, vehicle safety, and running costs in ways we often don’t realize. Knowing about it can help us better assess road conditions and demand better quality in road construction and maintenance.
If anyone has traveled from Villupuram to Pondicherry, you’ll understand just how bad the newly constructed cement pavement road really is. Despite being a new road, it’s in such poor condition that you wouldn’t even feel like you’re driving on a freshly built highway. The ride is rough and uncomfortable, with constant vibrations and harsh bumps that make the journey tiring and stressful. It’s deeply concerning that such a recently completed road is already in this state, especially considering the toll charge for a car is ₹95 for a return trip. It raises serious questions about the quality of construction.
I’m getting city-level mileage figures while driving on this road, even though I’m traveling around 50 kilometres.
Throughout the entire stretch, you can feel constant vibrations. Every bridge will definitely damage your suspension if you drive at more than 60 km/h. You don’t even have to count how many bridges you’ve crossed—if you have a dashcam installed in your car, it will automatically get recorded as an emergency video for every bridge.
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