Towards Climate Resilience: A Streetside View

In December 2023, the floods in Chennai and neighboring districts of Tamil Nadu wreaked havoc on the lives and livelihoods of thousands of people. However, Tamil Nadu is not the only state to be impacted by the rising hazards of climate change. Cities across India continue to grapple with the crisis. By 2030, 40.76% of India’s population is expected to reside in urban areas. To meet this pace of urbanization, a lot more public infrastructure will have to be added to our cities. As we plan this necessary infrastructure, it is crucial to account for its impact on the environment and take judicious steps to improve the quality of life in our cities.

The Concrete Challenge

One of the most widely used materials for building streets is concrete (sand, gravel, cement and water). Selected for its strength and durability, the impervious nature of a concrete surface does not allow stormwater to seep through, increasing surface runoff and contributing to urban flooding. Another concern is its role in exacerbating urban heat. Road infrastructure with little to no vegetation, coupled with densely packed buildings along the edges, leads to the creation of urban heat islands or urbanized areas that experience higher temperatures than outlying areas. For example, land surface temperatures recorded at the Andheri Ghatkopar Link Road in Mumbai shows at least a 3 degree Celsius rise between 2005 and 2020 in the highest and lowest recorded temperatures across the stretch (Figure 1).

There is a growing interest in greening our urban spaces and creating more sustainable and environment-friendly public spaces. However, the transition from conceptualization to implementation remains a challenge. Cities have already invested substantial public funds in constructing concrete streets, making it financially and logistically daunting to modify them to integrate newer solutions. We look at four ways in which cities can enable resilient streets.

Reimagining Materials

Developing building infrastructure that is truly resilient to the effects of climate change will need a complete overhaul of the materials currently being used. Creating more pervious surfaces in our cities is a fundamental and crucial step. Integrating permeable street infrastructure, such as porous pavements or bioswales, allows stormwater to seep through the ground, replenishing groundwater resources and reducing surface runoff. While alternatives to concrete, like porous asphalt or permeable interlocking pavers do exist, there is a need to study their ecological impacts and effectiveness. Investing in research and innovation for materials that offer a sustainable and green alternative to concrete must take place as part of any material overhaul. Portland, the most populous city in the state of Oregon in U.S., has a Green Streets Program that serves as an excellent example of this. Studies show that street design, that took into consideration rain gardens or bioswales, demonstrated a reduction in peak flows from their drainage areas by at least 80%.

Redefining Processes

Typically, municipal agencies adhere to a unified schedule of rates which specifies a standard list of materials for street construction. Introducing new materials is often a time-consuming approval process. There is a pressing need for a more agile and adaptive approach by municipal agencies to enable the easy integration of environment-friendly materials into construction practices.

Co-creating Solutions

Although the process of transforming streets is time-consuming, with projects typically taking up to two years for completion, it is essential to consider intermediate solutions that are quick, cost-effective and adaptable. Contractors, civil engineers and industry experts are key stakeholders, and their expertise must be leveraged to arrive at interim and long-term solutions. Fostering collaboration and promoting peer learning among all stakeholders is key to realizing innovative solutions for Indian city streets.

Looking at Streets as Ecological Landscapes

Green spaces, within existing public infrastructure and spaces, can be enhanced by adding vertical gardens or vegetation. Additionally, increasing the storage capacity of drainage systems enables cities to better manage stormwater during heavy rainfall, reducing the risk of flooding and waterlogging.

In 2017, the city of Medellin in Colombia undertook an initiative to build an interconnected network of 30 green corridors to tackle the severe urban heat island effect it was facing. Adding more vegetative cover through plantation, green roofs and vertical gardens along transit infrastructure has not only helped them reduce the average city temperatures by 2 degrees, but also increased the number of bicycle trips by 35% while significantly reducing air pollution. It is evident that integrating nature into the urban fabric is key to fostering resilient and humane urban environments.

It is imperative that we look at streets as more than just conduits for mobility. Creating pedestrian-friendly environments with ample shade and amenities encourages active transportation, fostering healthier and more vibrant communities. Streets are the largest contiguous public space in our urban areas and making this street network climate resilient offers the opportunity to catalyze transformative change in our cities.

All views expressed by the author are personal.