Vehicular Greenhouse Gas Emissions and Spatial Temporal Traffic Patterns in Gorakhpur City

In the bustling cities of India, the air is thick with the exhaust of millions of vehicles. This exhaust does more than just create a haze; it releases invisible gases that trap heat in the atmosphere, slowly warming the planet. While carbon dioxide is the most famous of these gases, it is not the only one. When fuel burns, it also releases smaller amounts of methane and nitrous oxide. Although these gases are emitted in much smaller quantities than carbon dioxide, they are far more potent at trapping heat. To understand the true impact of a city's traffic, scientists must add these powerful trace gases to the mix, converting them into a single, unified measure of climate damage. This approach allows researchers to see the full picture of how transportation contributes to global warming, moving beyond simple counts of smoke to a deeper understanding of the planet's heating.

In the city of Gorakhpur, a rapidly growing urban center in the north, researchers set out to measure this hidden heat. They chose two very different locations to stand and watch the traffic flow. One spot was the main gate of a university, a narrow, crowded institutional hub where students and staff converge. The other was a mixed residential and commercial area, where the traffic moved more freely through a network of homes and shops. For seven straight days, from Monday to Sunday, the researchers stood at these fixed points, manually counting every vehicle that passed by. They did not just count cars; they sorted them into specific groups: two-wheeled motorcycles, gasoline cars, diesel cars, vehicles running on compressed natural gas, three-wheeled auto-rickshaws, and large heavy-duty trucks. By tracking these vehicles during morning, afternoon, and evening hours, they built a detailed map of how the city breathes and moves.

The results revealed a surprising truth about who is responsible for the city's carbon load. One might assume that the large, heavy trucks or the powerful cars would be the biggest polluters. However, the data showed that two-wheeled motorcycles were the primary contributors, accounting for nearly half of the total emissions at both locations. This was not because each motorcycle was a massive polluter on its own, but simply because there were so many of them. Their overwhelming numbers in the traffic stream meant that, collectively, they generated more greenhouse gases than any other single type of vehicle. Gasoline cars came in second, followed by diesel vehicles, while the cleaner-burning natural gas vehicles and heavy trucks made up the smaller shares.

The study also uncovered how the city's rhythm changes the air quality over the course of a week. At the university gate, the pollution levels were volatile, spiking dramatically on Sundays. This was not a typical workday rush; instead, it reflected a weekend surge of people traveling for shopping and leisure, creating a sudden, intense burst of emissions that reached nearly 377 kilograms of carbon dioxide equivalent per hour. In contrast, the residential area showed a steadier pattern, with emissions rising gently in the middle of the week and dropping on Fridays. This difference highlights how the purpose of a neighborhood dictates its pollution profile: institutional zones react to the ebb and flow of events, while residential corridors maintain a consistent, predictable baseline.

Perhaps the most critical finding of the research was the danger of looking only at carbon dioxide. When the researchers added the effects of methane and nitrous oxide into their calculations, the total climate impact of the traffic increased significantly. These trace gases, though invisible and present in small amounts, act like a hidden multiplier, amplifying the warming effect of the exhaust. If city planners were to rely only on raw carbon dioxide numbers, they would be missing a substantial part of the problem. The study suggests that to truly manage the environment in growing cities like Gorakhpur, officials must design strategies that account for this full spectrum of gases. This means recognizing that the sheer volume of two-wheelers is the main driver of emissions and that accurate climate audits require looking beyond the most obvious pollutant to see the complete thermal footprint of the city's movement.