Road To Road Resilience Is Paved With Mindful Design & Construction

Road networks play a pivotal role in the development of any country. But what happens when the roads themselves crumble under the pressures of a flood or landslide?

India’s road and highway network increased by 59% from 2013-2014 to 2022-2023, according to the Ministry of Road Transport and Highways. Much of this new infrastructure is exposed to hazards that are intensifying or becoming more frequent on account of climate change.

The Himalayan states best exemplify these risks. Last year, torrential rain and floods led to the damage of at least 40 bridges in Himachal Pradesh. In Uttarakhand, pilgrims were left marooned after widespread damages to road infrastructure. Every year, these states are faced with worsening impacts, affecting both assets and livelihoods.

Climate change isn’t the only factor to blame. Experts also point to the “unscientific” road cutting methods and poor construction that have added to slope instability. The unprecedented losses and damages from last year’s deluge have jolted state and central governments into action.

“The government realises a lot of money is being spent on creating roads which are washed away and not serving their purpose,” said Anil K. Gupta, a professor at the National Institute of Disaster Management, adding, “They want to understand what measures need to be taken to improve road resilience.” Led by Gupta, the NIDM is in the midst of identifying vulnerable highways to formulate guidelines and better inform the planning and construction of highways in India.

Building roads in the Himalayas

Himachal Pradesh’s 73,230 square kilometre road network is the lifeline of its economy, providing the means for tourism, horticulture, and forestry activities to flourish. The unusually heavy rainfall last year took a toll on this critical infrastructure, however, damaging 8,040 km of road, accounting for 21% of the total road length in 12 districts, according to the state’s post-disaster needs assessment.

The reason for widespread damage is that the state experienced 431% more rainfall than normal between July 8 and 12, 2023.The estimated cost of losses and damages to the state’s road infrastructure is Rs. 1,633 crores, with recovery and reconstruction expected to be even higher, at Rs. 2,438 crore.

A number of factors contribute to a road’s vulnerability, said Amit Prothi, director general of the Coalition for Disaster Resilient Infrastructure (CDRI). “A lot of potential damage could come from the location of the road. The second factor adding to vulnerability is changing context. A road could be constructed along a forested patch, but in ten to fifteen years’ time, that could change, which changes the risk profile completely. The third is changing weather patterns, and the fourth is road construction itself,” he said.

The CDRI is assisting the Himachal Pradesh government in improving its road infrastructure in the aftermath of last year’s damage. “There are a few approaches we take when doing our assessments. We check to see if existing standards and guidelines are taking risk into account, What kind of technology is being used in these locations, and finally, does the state have the right capacity, and the correct engineers to address this problem?,” said Prothi.

Among the roads that have been “put to extreme stress” were stretches of two four lane highways, NH-5 and NH-21, laid by the National Highway Authority of India (NHAI), the post disaster needs assessment says. Both highways are marred with controversies that demonstrate some of the issues in highway construction. A public interest litigation alleged the NHAI, public works department, and its contractors cut the slope vertically along the Parwanoo to Solan stretch of the NH-5 in Himachal Pradesh, endangering slope stability.

Another case filed against NHAI and its contractors, along Kiratpur-Manali stretch of NH-21, alleged the road alignment was surreptitiously changed to the benefit of those whose land would be acquired for road widening. On the same route, illegal muck dumping from road projects led the High Court to impose a fine on the forest department for “protecting the guilty.”

The NHAI has earned the rap of the Himachal High Court, which asked the agency to share status reports of progress of maintaining the highways. “We recommended technical investigations be done to understand what protections are needed in the Parwanoo to Solan stretch, because adequate protective measures were not in place,” said R.K. Pandey, a former member of NHAI (Projects) and head of the committee tasked with surveying the damage.

The committee reportedly found 176 defects along the problematic stretch, and that the detailed project report (DPR) designed by contractor G.R. Infrastructure was limited in scope. According to the committee, the road should have been a two-lane project, as opposed to a wider four lane. “Contractors may design for the road, but designing and implementing additional protective measures shoots up the cost many folds. We tend to see contractors employing cost cutting measures that can lead to design flaws with huge repercussions,” said Pandey.

Typically, slope stabilisation techniques involve using materials like stone, reinforced concrete and steel to create retaining walls which hold the slope in place. “These are rigid structures which can collapse under tectonic movement and heavy rainfall conditions, because they’re not designed to handle heavy water flow from erratic rainfall,” said Ratnakar Mahajan, technical manager of Maccaferri India, a civil, geotechnical and environmental construction company offering technical solutions for disaster management. “Depending on the location, using reinforced soil, which is sourced locally, can reduce the carbon footprint of materials and offer a more flexible solution. Reinforced soil can accommodate tectonic movements without losing its structural integrity, and they’re porous, allowing for the drainage of water,” he added.

The business of subcontracting

In a statement earlier this year, Union Minister of Road Transport and Highways, Nitin Gadkari, expressed his dismay at the poor quality of DPRs in highway construction. “In the last 10 years, no good work had been done in preparation of DPRs. I am worried about the poor quality of DPRs prepared by consultants,” he was quoted as saying.

The NHAI contracts work to agencies who undertake surveys and design the project before beginning on implementation. A detailed project report or DPR includes prospective budgets, surveys of the area, and plans for maintenance of the structure. But contractors hired by agencies like the NHAI may not always have the experience or equipment to carry out road construction for challenging terrains subject to climate hazards. The NHAI had said, for example, that the failure of the Parwanoo-Solan route was a “learning experience” for the agency.

A study aimed at understanding the critical factors influencing the performance of highway projects found that contractors face four challenges: constraints in execution, operational difficulties, constraints imposed by stakeholders and political entities, and design constraints.

Damaged equipment and lack of knowledge about proper equipment “indicates…the lack of availability of skilled operators,” said the study. It also found that “a rise in the number of unplanned settlements in the vicinity of a road project creates several constraints, e.g., errant traffic assessment, design errors in culverts and overpasses. These errors further influence the alignment design, creating a variation in the quantities of work.”

Deforestation, unplanned urban growth, steep cutting of hill slopes, and improper drainage are the contributing factors that affect road and highway stability. “One of the most common issues is the clogging of culverts and the lack of stepped chutes on the downhill side for proper drainage,” said P S Prasad, chief scientist at the CSIR-Central Road Research Institute (CRRI). Drains and culverts play the crucial role of channelling water down the slope, allowing it to drain. “Culverts need to be of the proper size and number to ensure water can flow freely.”

Earlier this year, the NHAI signed a memorandum of understanding with the Geological Survey of India (GSI), agreeing that the latter will “provide services to NHAI for site specific geotechnical consultancy and assist in vetting of Detailed Project Reports (DPR) from geotechnical point of view.”

Improving road resilience

Improving road resilience, particularly of highways, may require guidelines in addition to the existing codes and standards governing road construction, says Gupta of the NIDM. The Indian Roads Congress (IRC) is the primary body that sets protocols, guidelines, and standards for road making. The IRC’s Hill Road Manual was revised in 2023, after 25 years, to include newer protocols on slope stabilisation and hill cutting.

“Generally, parameters used to design road infrastructure don’t take extreme events into account, and that’s one of their limitations,” Gupta said, adding, “These standards and guidelines are more technical in nature, but we also hope to come up with management codes.”

The National Highway Climate Adaptation Policy and Guidelines project, called HighCAP, aims to “integrate disaster risk reduction (DRR) and climate adaptation practices into the highway sector.” The National Institute for Disaster Management has surveyed 2,000 kilometres of highways and identified 30 hotspots where highways are exposed to a variety of hazards, such as floods, excessive heat, coastal flooding, chilling, and cyclones.

The purpose is to come up with cost-effective remedial measures in the face of climate impacts, but also to enforce more oversight on construction work, said Gupta. “Once the work is subcontracted, you never know whether they’re following the guidelines and manuals. They don’t have the technical capabilities sometimes, or aren’t trained properly. How many resources are going into timely site inspections by agencies? We hope to come up with guidelines for this, too,” he said.

Several engineering techniques can help prevent disasters like landslides, said Prasad of the CRRI, who contributed to the 2023 edition of the Hill Road Manual. Some of these techniques include constructing gabions (a type of wired basket filled with various rocks or soil to help prevent erosion), applying shotcrete and steel rope nets on exposed rock to hold falling rocks, and inserting self-driven anchors (used to stabilise unsteady rock and soil formations) to ensure slope stability.

Bioengineering, such as planting native tree species along the slope, is another solution to improve soil stability along slopes that can support vegetation, said Prasad. “But all these measures require proper geological, hydrological, and geotechnical investigations and design,” he said.

(Published under Creative Commons from Mongabay-India. Read the original article here)