The challenge of our generation.
The opportunity of a lifetime.
Energy and carbon performance as the core of sustainability is the defining challenge of our generation. The triple bottom line requires that we urgently reassess how we deliver economic, social and environmental alternatives to the current extractive ‘take-make-dispose’ practices of roadbuilding.
This is an immense challenge if we are to meet emissions targets. The world’s road infrastructure is comprised of over 40 million miles of roads. Even for routine maintenance of existing paved roads, it is estimated that the road construction sector will use a staggering two billion tons of fossil oil based HMA material every year across approximately 600,000 miles, which is more than the distance to the moon and back. Further, according to McKinsey’s 2021 Road Work Ahead report, the US and EU alone will spend around $280 billion every year on road construction, using over 720 million tons of energy and carbon-intensive road-building materials.
Is this sustainable?
Non-integrated and incremental efficiencies that may come from A.I., machine learning, automation, autonomous vehicles, and chemically modified versions of fossil oil-based bitumen binder will simply be too little and too late. The International Panel on Climate Change (IPCC) has reported that we are on a trajectory to exceed the global warming limit of 1.5°C versus pre-industrial levels. This means that trillions of dollars in transportation assets will be even more vulnerable to the shocks from extreme heat, precipitation and flooding that will result from climate impacts. In turn, these stresses will translate directly to premature rutting, cracking, moisture damage, and significant overall reductions in the useful service life of our roads to the tune of hundreds of billions of dollars.
Where will all this funding come from?
According to American Society of Civil Engineers (ASCE) and their latest 2021 Infrastructure Report, the U.S. has been underfunding its roadway maintenance for years already, resulting in a $786 billion backlog of road and bridge capital needs that is causing a further $1,000 per motorist per annum in wasted time and fuel. Root-level innovations in sustainability and resilience will be key to surviving and thriving through these challenging times.
History teaches us that we can rise to the challenge when we come together; an approach that has been evidenced throughout history. The Montreal Protocol’s halting of 98% of the consumption and production of CFCs to stop and reverse the depletion of the ozone layer in just over a decade is a good example. The Sulfur Breakthrough in roadbuilding in the early 1980s is another.
The use of sulfur in road construction was first developed and deployed in 1979 as a response to the world’s first and second oil shocks. The U.S. Army Corp of Engineers, the U.S. Bureau of Mines, the Federal Highway Administration (FHWA), State DOTs, academia, The Sulphur Institute, and private enterprises came together in a rare multi-stakeholder innovation to address the shortage of bitumen supply for the country’s road infrastructure. In 1980, the U.S. Department of Transportation heralded the innovation as The Sulfur Breakthrough. However, when the geopolitical tensions eased and the world’s oil prices normalized in the mid-80s, the industry went back to business as usual, relying on the fossil oil-based bitumen binder and a focus on virgin mined aggregates.
Post-construction evaluations of sulfur-enhanced asphalt (SA) roads in 18 different states across various climatic zones found them performing as well as, or even outperforming, conventional bituminous asphalt road counterparts. Despite this achievement, the status quo remains today.
We are now faced with a confluence of new challenges: environmental, geo-political, energy, and economic. These conditions combined with technological advances represent major opportunities, but only if we can come together and embrace root-level changes: with the binder, because at present it is fossil fuel-based; with aggregate choice, because we cannot sustain 90% virgin aggregate use; and over time with process change away from the energy and carbon intensive methods of the previous generations.
We must consider more sustainable, more resilient and more recyclable materials for our base binders and for use within existing process; this with an eye to new networks and collaboration to achieve a fresh sustainable worldview of roadbuilding.