Rocky Road to sustainability

Construction Methodologies

Waste plastic, when used to construct roads, replaces fossil-based bitumen which brings down emissions and leads to long-lasting pavements. One kilometre of road construction consumes almost a ton of waste plastic. This technology gives sustainability and allows for plastic waste disposal.

Asphalt pavements are constructed at a temperature of 160 degrees Celsius and heated bitumen gives rise to emissions. Construction of one kilometre of a single lane produces emissions equivalent to 200 cars running 24×7 for one year. Warm-mix asphalt technology brings down construction temperature by 50 degrees thus reducing emissions.

Stabilization methodology allows for adding two percent cement into conventional GSB mix to improve its strength from 200 mega pascals to 1700 mega pascals. This allows for sustainability. This methodology also reduces crust thickness by 25%, thus consuming less materials, having fewer transportation runs and reduced carbon emissions. It also lessens the use of non-renewable aggregates.

Bio-binder is fossil-based bitumen that is replaced by bio waste like ‘parali’ or stubble that otherwise farmers burn. Rather than burning the stubble, it can be used to make bitumen by a chemical process called pyrolysis. Not only is this a solution to waste disposal, it also saves on the import of bitumen.

World Bank studies have proven that if you do not design and do not maintain your infrastructure right, in anything between 10 to 15 years you will end up spending a humungous amount of money reconstructing that infrastructure. Which again means use of natural resources and which again questions your entire sustainability footprint.

Neha Vyas
The World Bank

 

Other factors

Environment sustainability in the highways sector is affected by additional factors that cannot be overlooked. One of them is the water footprint. With water crisis in many districts every summer, supporting other sectors of the economy like industry over and above domestic needs may be unrealistic and needs to be addressed for sustainability. However, energy footprint and rationalization, another key factor, is progressing well in the country. The third important aspect is undermining and reducing wilderness areas which support clean air. Sequestering carbon generated during emission using plantation programs, revival of coastal areas, sea grasses and mangroves is another key aspect. Other factors include resilient infrastructure to prevent re-construction, citizen participation and governance which are important aspects of the sustainability debate. They are all linked to the larger formats of technology, material efficiency, equipment, manufacturing and recycling.

Protocols for carbon measurement

There are different models for carbon measurement available like CHANGER, which was adapted by the Indian Roads Federation. A data-intensive model has been developed by the World Bank. Other models include the ones developed by ADB and FHWA. However, these models are not adequate to be converted into carbon credits. The first step is to establish feasibility for the sector with the help of third-party consultants. The road construction industry has several segments from mining, operation and material extraction to recycling. These can be broken into different stages, applying for credit segment-wise or for the complete life cycle of a project. Since studies have shown differential results over time, there is no one credible model to bank on as of now. The second step is to have a baseline against which performance can be measured. The third would be registration followed by validation. The IRC, after a decade of struggle, came out with the carbon footprint manual in 2020 with a simple co-efficient based on the conventional way of road construction. Projects could use that baseline as their benchmark for a start. However, industries will have to invest in developing standard validation methodologies to avail of carbon credits.

The approach we have adopted is life-cycle costing rather than going for the short-term. It will reduce materials, inconvenience to the public and save fuel. In the latest Ghaziabad – Aligarh project, where the pavement condition was not good, we went ahead with Cold Central Plant Recycling (CCPR) technology to build the ramp. It was 90% CCPR and
10% was aggregates. We have saved equivalent to 1,30,000 metric tonnes of carbon in all.

Bovin Kumar
Cube Highways and Transportation Assets
Advisors Pvt. Ltd

Equipment efficiency

There is currently no standardisation in biofuels. Equipment agencies are unaware where to procure them and in rentals, the fuel is in contractor’s scope. Contractors are using biofuels to lower emissions but since there are no norms in place, there is no verification process to ascertain the right kind are being used. Loaders, forklifts, and some cranes have recently launched electric versions but converting all equipment to EV will take time.

Challenges for Constructors:

Availability of the right kind of equipment with small contractors is an issue. It is not always possible to engage large contractors like L&T and HCC for small maintenance projects and smaller contractors are unable to supply equipment with specific warp attachments, as an example. Another challenge is the restriction caused by standardisation and the number of approvals to be sought before implementing new technology. This however has been done away with as the construction engineer takes responsibility for service levels. The major challenge is data.

There is no single database where India-specific data can be stored and retrieved as a resource bank for people in the industry. The second major challenge is availability of skilled manpower. This extends from the operator who is not aware of the full capabilities of his equipment to the engineer who is not aware of pavement construction. Some engineering institutions still run old courses and have 1 – 1 ½ month of internships for civil engineering. This is inadequate and institutions should go with 6 months to one-year internships if the industry is to get the real engineers.

I think telematics and IoT should come up in a very big way, just to get things organized. When we talk about fleet management it has to come up with the right IoT and telematics. We can see a lot of fuel sensors that are being fit into equipment nowadays and this is helping rental companies and contractors.

Satin Sachdeva
Construction Equipment
Rental Association

 

The road ahead

Research institutes are readying technologies but there is no alignment with consultants, construction agencies and other stakeholders. This needs to be addressed. Contractors have to be given incentive to reduce carbon emissions. There needs to be a policy that when a project is to be tendered, only contractors with the lowest carbon emissions will be qualified to bid. There is also a need for a certifying body that can verify that a project can be listed as a lower-carbon-emission project. While there are many tools available including GaBi, SimaPro and CHANGER, each of these gives different results. As of now there is no data on the carbon emission of a typical highway construction project in India.