India has built an extensive road network that is vital for transportation, trade and commerce. With a road network of over 6.5 million km as of March 2023, it has the second largest road infrastructure after the United States. With road density of about 1.94 km per sq km of land, India’s road infrastructure is comparable to that of Hong Kong. This extensive road network facilitates the transportation of 64.5 per cent of goods within the country while approximately 90 per cent of India’s total passenger traffic relies on these roads for commuting. However, traditional road construction methods have a significant impact on the environment, contributing to deforestation, breaking mountains, soil erosion, and carbon emissions. While constructing roads, factors like land preparation, emissions from concrete, asphalt, steel and construction vehicles collectively contribute to environmental degradation, conflicting with India’s goal of achieving net zero emissions by 2070. To address these challenges, the construction industry is transitioning to sustainable methods that prioritise environmental protection, durability and cost-efficiency. This marks a new phase in infrastructure development, promising to transform road construction for a more sustainable future.
Innovation in materials and techniques for sustainable highways
At the heart of sustainable road construction lies innovation in materials and techniques to build better roads for a greener future. Traditional asphalt, derived from fossil fuels, has long been the standard material for constructing road surfaces. However, its production process generates substantial greenhouse gas emissions and relies heavily on non-renewable resources. In contrast, alternative materials such as recycled asphalt pavement (RAP), recycled concrete and bio-based binders offer promising solutions to mitigate environmental impacts. RAP utilises reclaimed asphalt from existing roads, reducing the demand for new aggregates and cutting emissions associated with asphalt production by up to 20 per cent, as per recent studies. Similarly, incorporating recycled concrete into road construction not only diverts construction waste from landfills but also reduces the need for virgin aggregates, conserving natural resources.
One notable sustainable road construction method gaining traction is full depth recycling (FDR) combined with soil stabilisation. This innovative approach reduces the need for stone aggregate by almost 85 per cent, eliminating the environmental impact of extracting aggregate by breaking down mountains or hills. With a saving of 2,130,000 tonnes of stone aggregate and a reduction of 46,800 tonnes of carbon emissions in trial projects, the environmental benefits turn out to be substantial. FDR and soil stabilisation represent a significant step towards sustainable road construction by minimising resource extraction and emissions. The key to this approach consists of natural mineral-based additives which when mixed with cement creates a strong sub-base, the heart of the road design. FDR uses the existing soil from the surface, irrespective of its properties and enables the new mixture to create a strong road mix. Usage of existing soil by the additive ensures no new stone aggregate is needed in the construction process, thereby reducing the demand for stone aggregate, which ends up in hills/mountains not being mined/destroyed to create stone aggregate. This indirectly reduces carbon emissions on transport and mining. FDR is a method that has been used across the globe over the last few decades. It started back in the 1940s during World War II and has prevailed ever since. Several European countries with extreme weather conditions resort to FDR due to its fast curing process that enables roads are built faster than conventional processes, in addition to have an eco-centric edge. One of the key attributes of FDR apart from it being a green process is the ability to finish construction in record times. Saving time leads to saving cost, reducing traffic obstacles during the construction phase and ensuring roads are ready to be used at the earliest without causing inconvenience to the commuters.
At the same time, technological advancements in pavement design and construction techniques are also improving road durability and resilience, extending lifespan while decreasing maintenance needs. Techniques such as pavement recycling and rehabilitation enables the revitalisation of ageing road infrastructure which eventually minimises the need for costly reconstruction projects and conserving materials.
In India specifically, these mineral based additives used for FDR and soil stabilisation have to be approved and validated by reputed institutions and associations like the IITs, IRC, CRRI and likewise.
Smart infrastructure revolutionizing road design and management
The concept of smart infrastructure is reshaping the way roads are designed, built and managed. Incorporating sensor technologies, data analytics and intelligent transportation systems (ITS) into road infrastructure enables real-time monitoring of performance, traffic flow and environmental conditions. Smart sensors embedded within roads can detect signs of deterioration, traffic congestion or adverse weather conditions, enabling proactive maintenance and timely interventions to enhance safety and efficiency. Leveraging data analytics and predictive modelling enables planners to optimise road designs, improve traffic management strategies and reduce environmental impact, thereby creating smarter and more sustainable transportation networks.
Accelerating towards sustainable road construction
The transition to sustainable road construction is already underway in many parts of the world, driven by a growing recognition of the urgent need to address climate change, resource scarcity and infrastructure resilience. Governments, industry stakeholders and research institutions are collaborating to develop and deploy innovative solutions that balance environmental, economic, and social goals. From pilot projects experimenting with alternative materials to large-scale infrastructure initiatives embracing smart technologies, the momentum towards sustainable road construction continues to gather pace. Sustainable infrastructure projects create opportunities for job creation, innovation and economic growth in areas like green technology, recycling and sustainable materials. Thus, the drive towards sustainable highways is accelerating through collaborative efforts across sectors.
Revolutionising road construction involves rethinking how we develop and maintain infrastructure to serve the current and future needs of the society. A significant focus has been directed towards enhancing road sector connectivity and infrastructure improvement through various national initiatives such as the Bharat Mala Project, Pradhan Mantri Gram Sadak Yojana (PMGSY), Mukhaya Mantri Gram Sadak Yojana (MMGSY) and Special Accelerated Road Development Program in the North East.
Several state governments have been exploting the FDR technology with additives and Uttar Pradesh led this movement for their rural roads across the state under Uttar Pradesh Rural Road Development Agency (UPRRDA), thereby saving thousands of tonnes in stone aggregate and reducing carbon emissions.
FDR has even gone a step ahead, beyond roads, to construct runways and taxiways of busy airports. One classic example is of the GMR International Airport Hyderabad where over 700,000 sq.m of runways and taxiways were constructed using FDR.
By adopting sustainable materials, innovative techniques, smart technologies and lifecycle thinking, we can build roads that connect communities while also preserving the planet. Though the path to sustainable highway construction has challenges, the outcome of cleaner, safer, more durable transport infrastructure makes the effort worthwhile. Embracing green roads and lifecycle thinking can create a transportation system that serves both current and future generations.