Diamond Grinding: Path to Smoother, Longer Lasting Roads

Pavement techniques such as diamond grinding is a highly effective method for restoring and maintaining concrete and asphalt pavements.
Nick Davis, Director - Technical Services, International Grooving and Grinding Association (IGGA)

Diamond grinder in action (Photo credit: IGGA).

India’s national highways are the backbone of the country—facilitating trade and commerce, connecting rural areas to cities and providing access to essential public services, including healthcare and education. Yet, due to rapid urbanization and a growing number of private vehicles, national highway officials are facing multiple challenges including traffic congestion, road safety, resiliency and efficiency, as well as the constant need to maintain and expand the existing infrastructure.

These challenges also present opportunities for innovation and investment in modernizing infrastructure, implementing intelligent transportation systems and promoting sustainable practices. To elevate its highways to world-class status, India can adopt innovative pavement techniques such as diamond grinding. Recognized as a highly effective method for restoring and maintaining concrete and asphalt pavements, diamond grinding offers a path to smoother, longer lasting and efficient roadways.

Diamond Grinding Technology

Diamond grinding is a pavement restoration technique that enhances the ride quality, smoothness and serviceability of deteriorating road surfaces. Utilizing a self-propelled machine armed with closely spaced diamond saw blades, the technique involves methodically removing a thin upper layer from the road surface. The precision and lasting impact of diamond grinding elevates it above other resurfacing methods like asphalt overlays. By targeting only surface irregularities, diamond grinding restores a road to near-original (or better) conditions without compromising its structural integrity.

Originally developed in the 1960s in the United States, the technique has rapidly evolved to become a gold standard for concrete pavement restoration worldwide. Its applications range from correcting faults and bumps to reducing noise pollution and improving traction. Whether for newly constructed roads or decades-old highways, diamond grinding is a long-term solution for maintaining road performance and safety.

With more attention than ever being focused on energy conservation, vehicle fuel efficiency, and new alternatives such as hybrid cars and biodiesel, few people realize the significant impact that road rehabilitation methods like diamond grinding can have on energy use.

Research by the MIT Concrete Sustainability Hub concluded that roughness and deflection of pavements impact the fuel economy of vehicles that traverse the pavement. When the pavement surface is smooth, vehicles traverse it more efficiently, with more of the expelled energy dedicated to forward movement rather than fighting vertical bouncing movements.

Even when considering alternative fuel vehicles, such as electric vehicles (EV), it is important to recognize that the battery of an EV traveling on a smooth, diamond ground pavement will carry the vehicle for a longer distance because it can move more efficiently. Although, at this time, research has not been done to show exactly how much improvement takes place, MIT researchers suggest the expected increased distance would be the same as the percentage of fuel saved for their gasoline-powered counterpart.

By removing faulting, slab warping, studded tire wear and unevenness resulting from patches, diamond grinding creates a smooth, uniform pavement profile. The longitudinal texture created by diamond grinding also enhances macro texture and skid resistance in polished pavements.

Key Benefits

Enhanced Smoothness: In a 2000 article by the United States Federal Highway Administration (FHWA), Enhancing Pavement Smoothness data was evaluated showing that the smoother a pavement is, the longer it will last. This is the result of reduced frequency and severity of dynamic loads applied to the pavement surface. Roads treated with diamond grinding exhibit significantly lower International Roughness Index (IRI) values, translating to better-performing and longer-lasting surfaces. Additionally, smooth pavements improve user comfort and minimize vehicle wear and tear.

Improved Safety: Diamond grinding enhances road safety by eliminating surface irregularities such as bumps and dips. Increased macro texture reduces the risk of hydroplaning and improve skid resistance—ultimately reducing accident rates, especially in wet weather conditions. Research conducted by the Wisconsin Department of Transportation and the Marquette University Transportation Research Center reports a 57% reduction in wet weather accident rates for diamond ground surfaces. In addition, diamond-ground surfaces have a 42% reduction in all-weather accidents.

Noise Reduction: Rough pavements and transversely tined pavements have a higher decibel reading compared to smooth and longitudinally ground pavements. According to the FHWA, highway noise is typically 70 to 80 dB(A) when standing 50 feet from the highway. Sounds more than 80dB(A) can cause hearing damage after extended exposure. Diamond grinding creates a unique longitudinal texture on the road surface, reducing tire-pavement noise significantly. This feature is particularly valuable in urban and residential areas, where noise pollution is a growing concern.

Durability and Longevity: Roads treated with diamond grinding enjoy extended service life, often lasting decades before requiring additional intervention. This is particularly advantageous for high-traffic highways.

Environmental Sustainability: Compared with traditional resurfacing techniques, diamond grinding generates significantly less waste, minimizes construction emissions and reduces urban heat island effects due to concrete's high albedo. It also promotes fuel efficiency by reducing vehicle rolling resistance. The nature of diamond grinding makes it one of the most efficient pavement preservation techniques. It can be completed in short lane closures for less time than typical asphalt overlays and may even be performed in a rolling closure next to live traffic.

In addition, overlays require the mining, producing and hauling of virgin material. Each one of these steps has a significant economic and environmental impact. Comparatively, a diamond grinding project only requires the removal of a small amount of material from the jobsite in the form of slurry.

John Roberts, Executive Director at IGGA summarizes the value of the technique, “Diamond grinding is cost-efficient and is the only highway surface treatment that is, in many situations, carbon negative.”

Impact of pavement roughness on fuel consumption, adapted from Zaabar and Chatti (2010).

Safety Grooving: Enhancing Traction and Saving Lives

In the 1960s, NASA developed a method that would help improve traction for aircraft landing on wet runways—safety grooving, a proven technique that significantly enhances road safety. Safety grooving, a complement to the diamond grinding process, was first implemented at airports and it took off. People quickly began to realize the benefits of using it elsewhere.

Safety grooving involves creating saw-cut channels into the pavement's surface, typically using circular diamond-tipped blades. Depending on the application, these grooves can be applied either longitudinally or transversely.

According to Roberts, “The whole idea behind this concept is that grooves carved into otherwise smooth surfaces will allow for water runoff, therefore improving traction. This all works the same way that tire tread patterns work to increase traction. So, implementing this method on roadways helps to bump up that traction even more.”

NASA’s research led to the standard acceptance of safety grooving of asphalt and concrete commercial runways around the world. In 1990, safety grooving was inducted into the NASA Hall of Fame.

Role and Advantages

U.S. municipalities and departments of transportation have found grooving to be an easily constructed and economical surface treatment that increases driver safety in wet conditions and saves on the costs of replacing or overlaying the pavement surface. Safety grooving is specifically aimed at improving traction, draining water more effectively and reducing hydroplaning.

Improved Traction: By embedding grooves into the pavement, the technique enhances friction between vehicle tires and the road surface. Studies show that longitudinal grooves align perfectly with tire treads, providing added directional stability against lateral motion. This added traction is vital for preventing skidding, particularly in wet weather.

Reduction in Hydroplaning: Hydrop- laning, where a vehicle loses contact with the road due to excess water, is a major contributor to highway accidents. Grooves act as drainage channels, swiftly moving water from under tires, significantly reducing the risk of vehicles losing control. Highway departments have determined the best way to decrease accidents during inclement weather is to remove water from the surface and increase the traction between the tire and the road.

The Department of Civil Engineering at the National University of Singapore conducted a study to evaluate the impact of various grooving patterns on hydroplaning. An in-depth evaluation of 132 different grooving patterns concluded that the speed a typical passenger vehicle could obtain before hydroplaning increases by about 2.8 kilometers per hour for every mm increase of groove depth, by about 3.5 kilometers per hour for every mm increase of groove width and by about 1.0 kilometers per hour for every mm decrease of groove spacing.

Accident Reduction: Safety grooving has demonstrated remarkable success in reducing accidents on grooved roads. Research conducted by the California Department of Transportation (Caltrans) revealed an average 69% decrease in accident rates on highways treated with longitudinal grooves, in both wet and dry conditions. On sections of Interstate 5, grooving successfully addressed escalating wet-weather accidents, cutting the total number by 83% over a five-year span.

Cost-Effective and Durable Safety Solution: Compared to high-friction surface treatments or asphalt overlays, safety grooving is an economical option that does not compromise on performance. It can be applied efficiently alongside diamond grinding, creating roads that stay safer for longer.

Ease of Construction: Safety grooving is straightforward to implement, requiring relatively simple machinery and minimal downtime. This makes it particularly suitable for high-traffic urban areas or critical highway stretches where reducing construction-induced disruptions is a priority.

Close-up view of a diamond-ground pavement surface (Image courtesy of IGGA).

Safety Grooving in Practice

Safety grooving presents a viable solution for enhancing road safety without the need for costly, resource-intensive resurfacing. By focusing on accident-prone zones such as steep curves, heavy rainfall regions, and high-speed stretches, safety grooving could significantly improve the safety of the country’s highways.

Already used extensively on bridges and airstrips worldwide—where safety is paramount—safety grooving holds promise for reducing skid-related accidents and enhancing overall travel security on Indian roads.

Opportunity for Diamond Grinding in India's Highway Infrastructure

The length of India’s National Highway network has surged by 60% in the last 10 years from 91,287 km in 2014 to 146,195 km in 2024, making it the second largest road network in the world, according to the year-end review of the Ministry of Road Transport and Highways. Recent programs like the National Highways Development Project (NHDP) and the Bharatmala Pariyojana are working to continue modernizing and expanding this network. However, challenges such as uneven pavement quality, frequent maintenance needs and outdated construction methods can hinder the system's efficiency.

Additionally, heavy monsoons, varying traffic loads and rapid urbanization exacerbate the wear and tear of road infrastructure. While traditional asphalt overlays are often used as part of India's road rehabilitation efforts, they provide only short-term relief. The rising demand for sustainable and cost-effective solutions presents an opportunity for diamond grinding, supported by safety grooving, to demonstrate their immense potential.

Leveraging Data for Environmental Impact

An important innovation demonstrating the environmental benefits of diamond grinding is the fuel/carbon savings calculator developed by MIT’s Concrete Sustainability Hub (CSHub) in collaboration with the IGGA. This tool evaluates the fuel efficiency improvements and carbon emission reductions achieved through diamond grinding by analyzing pavement roughness. By quantifying these metrics, the calculator ensures highway decisions align with sustainability goals.

An example of its application comes from Minnesota’s Chisago County. Following the diamond grinding on 26.4 lane miles of pavement, annual carbon savings reached 152,000 pounds, complemented by $3.5 million in fuel cost reductions over ten years. Such data underscores the immense environmental and economic potential of using this technology.

Cost Savings and Economic Benefits

Beyond safety and performance, the combined use of diamond grinding and safety grooving brings economic benefits. Fewer materials, reduced downtime and longer-lasting pavements make these techniques cost-effective solutions. With reduced wear and tear on vehicles and better fuel efficiency, governments and road users alike can experience substantial savings.

When highway maintenance crews reduce the IRI value of a pavement by 40%, it saves truck operators about .002 gallons of diesel or about .7 cents (U.S.) per truck per mile. While this figure seems negligible, it has a significant impact when entire highway sections are evaluated.

Implementation Insights

Successfully introducing diamond grinding and safety grooving into India’s highway ecosystem requires collaboration among policymakers, engineers and contractors. Measures include:

Training and Skill Development: Equipping contractors and engineers with the necessary skills to adopt these technologies is crucial to ensure proper implementation. IGGA provides technical resources and training modules to assist local industries in this transition.

Pilot Projects: Creating pilot projects on key highway corridors experiencing high traffic density can demonstrate their benefits effectively.

Collaboration with Government Programs: Integration with government initiatives like the Bharatmala Pariyojana could make these techniques a priority for road rehabilitation.

The Road Ahead

By adopting innovative pavement techniques such as diamond grinding and safety grooving, India can deliver a smoother, safer and quieter experience for drivers. Roberts concludes, “By integrating diamond grinding and safety grooving into its infrastructure, India has the opportunity to elevate its highways to global standards of quality and sustainability.”

About the author:

Nick Davis joined IGGA as Director of Technical Services in 2022 and he also serves as leader of the American Concrete Pavement Association’s Emerging Leaders Group.

 

Prior to joining the IGGA, Davis gained seven years of experience as an assistant engineer at the New York State Department of Transportation (NYS DOT), where he authored specifications and reports, managed a certification program for testing agencies that perform ride quality testing and managed specification and data collection for the first performance engineered mix (PEM) project in New York State. Many of the projects he was involved with were in the New York City area where design and traffic parameters were significant. He participates in the Road Profile User Group (RPUG) and National Concrete Consortium (NCC) and was selected to be the NCC state representative for the Northeast region.