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Vijay Naidu, a 49-year-old store manager, commutes 17 kilometres on motorcycle from his Madhavaram residence to Mylapore. “This is a 50-minute journey in the morning,” he told Down To Earth (DTE). “At night, the same distance takes 30 minutes as I go home late, during non-peak hours.”
Having commuted by two-wheeler since 2004, Naidu has seen firsthand the growing traffic problem in Chennai. He noted a significant increase in his travel time: “About 10 years ago, it would take me only 30 minutes to reach office and now it is 50 minutes,” he explained. Beyond the sheer volume of vehicles, Naidu added that recent road diversions and metro construction have exacerbated the city's traffic woes.
Meanwhile, Dever experiences similar, if not worse, delays in his 9 km car ride from St Thomas Mount to Tidel Park, an information technology park. His morning journey spans 45-50 minutes, while the return takes 40 minutes, both during peak hours. “The difference is because the return route is shorter,” he explained to DTE. “There is a lot of congestion at certain points in my travel. For example, I encounter traffic between Raj Bhavan and Madhya Kailash. Despite only being 3 km away, it takes me 20-30 minutes to cover that distance,” he added.
Over the past five decades, Chennai has experienced a notable shift towards personal vehicles for commuting. According to the 2018 Comprehensive Mobility Plan, the modal share for two-wheelers has seen a significant rise, starting from 2 per cent in 1970 and 3 per cent in 1984, increasing to 7 per cent in 1992-95, 25 per cent in 2008 and 29.6 per cent in 2018. Similarly, the use of cars and vans has also increased, from a 6 per cent modal share in 2008 to 7.1 per cent in 2018.
This increase in vehicular traffic has contributed to slower average speeds. Within Chennai city, the average vehicle speed is around 17 km per hour (kmph), lower than the Chennai Metropolitan Area’s (CMA) average of 25.8 kmph, based on the earlier CMA expanse of 1,189 sqkm. In 2022, CMA was expanded to 5,904 sq km.
As of 2018, Chennai district had 5.57 million registered vehicles, representing over 22 per cent of the total registered vehicles in the state, according to CMP. The compound annual growth rate for vehicle registration over the preceding decade was 6.3 per cent. Two-wheelers constitute most of these registrations at 79 per cent, followed by cars and jeeps, which together account for 16 per cent.
One of the factors driving this rising trend in private vehicle ownership, according to experts, is improved socioeconomic growth. Tamil Nadu’s real share in the country’s GDP, which was 7.8 per cent in 1990-91, increased to 8.8 per cent by 2021-22. The per capita income of Tamil Nadu State has risen from Rs 8,955 in 1993-94 to Rs 21,738 in 2002-2003, further increasing to Rs 2.78 lakh in 2022-23, 1.6 times the national average of Rs 1.69 lakh, showed data from the Chennai Metropolitan Development Authority and Tamil Nadu’s economic survey.
Siva, who lives in Ashok Nagar, prefers two-wheelers. “Having your own vehicle is more convenient and time-saving. I don't need to walk to the bus stop, wait for the bus, only to find it crowded. The other problem is safety,” said Siva, who spends Rs 2,500-3,000 a month on fuel.
Declining preference for buses is a major contributor to the transportation woes. The bus fleet hasn’t kept pace with the growing population, leading to longer wait times and overcrowding. “The number of bus stops has reduced and the distance between two stops has gone up, which means people must walk longer distances,” explained Shreya Gadepalli, founder and managing trustee of UrbanWorks, a non-profit institute based in Chennai. “So, they prefer having their own personal vehicles for convenience.”
Adding to the problem is the disproportionate population growth in CMA compared to the city itself. CMA has seen a decadal population increase of 27 per cent, while core Chennai city has grown by only 8 per cent. Despite this rapid expansion, the peripheral regions lack adequate bus connectivity. “Bus services have poor reach and frequency in many parts of Chennai, especially in the outskirts. Only 50 per cent of Chennai's citizens have access to frequent bus services within a reasonable walking distance,” Gadepalli pointed out.
“Chennai's population has increased from 10 million to 14.5 million, meaning a large share will settle in peri-urban places. But the supply of public vehicles has stagnated in the city. If there are no buses, people will buy two-wheelers,” said Jeyakumar, member secretary, Chennai Unified Metropolitan Authority (CUMTA), the nodal agency that brings together all agencies in the area of transport within CMA, told DTE.
With rising population, private vehicle ownership shot up, leading to increased congestion and pollution, highlighted the CMP report. A car, for example, consumes nearly five times more energy than a 52-seater bus with 82 per cent of its average load factor. Load factor is the ratio of the average load to the peak load for a certain period. A car occupies over 38 times more road space per passenger in comparison to a bus.
The rising rate of motorisation in Chennai directly contributes to air pollution, posing significant health risks, including premature deaths from respiratory ailments, cardiac disorders, strokes and diabetes. Road dust, vehicular emissions, construction activities and industrial effluents are the primary sources of this pollution, according to the Air Quality Monitoring, Emission Inventory and Source Apportionment Study for Chennai done by Indian Institute of Technology-Madras.
Urban hotspots such as Saidapet, Adyar Kasthuribai Nagar junction, Guindy Sardar Vallabai Patel Road X Taluka Office Road and Thiruvanmiyur (detailed in parts one and two of the Chennai mobility series) are severely impacted. These areas experience heightened vehicular pollution due to traffic congestion, which reduces vehicle speed and increases exhaust emissions.
Research underscores the impact of road transport on air pollution. A 2020 study in the journal Atmospheric Pollution Research identified it as the leading contributor to inhalable particulate matter (PM10 and PM2.5). PM10 has a diameter of 10 micrometers or less, while PM2.5 are generally 2.5 micrometers and smaller. These particles, once deposited in the lungs, can trigger tissue damage and inflammation.
A 2021 study published in Aerosol and Air Quality Research journal further revealed that Chennai’s ambient PM2.5 levels are 1.4 times and 5 times higher than the national standard of 40 microgrammes per cubic meter (µg / m3) and the WHO guideline value of 10 µg / m3 respectively.
Another 2021 paper in the journal Transport and Health brought attention to the hazards of prolonged waiting at bus stops. Given that bus stops are often situated on high-traffic arterial roads, passengers are exposed to elevated concentrations of PM2.5.
Between January and October, average hourly PM2.5 concentrations at bus stops were 44.2 μg / m3 and 48.5 μg / m3 respectively. A 15-minute wait exposed passengers to an average PM2.5 dose of 7.6 μg.
The paper concluded that “passengers waiting at bus stops are exposed to unhealthy magnitudes of air and noise pollution” and recommended that government consider pollutant exposure in the design of bus stops.
Chennai’s pollution levels escalate during winters, with the air quality index typically hovering in the 140-160 range, deemed unhealthy. An expert, who spoke to DTE on condition of anonymity, stressed the critical need to reverse the current modal share, where private vehicles account for 70 per cent of trips and public transportation only 20-30 per cent. “This reversal requires encouraging public transport use through improved last-mile connectivity (seamless connections from metro / bus stops to homes) and the development of transit-oriented development, which increases population density around transit hubs like metro stations (within 0.5 km),” the expert added.
Jeyakumar also highlighted the importance of strengthening intermediate public transport options like shared autos and auto-rickshaws to enhance last-mile connectivity. This includes rationalising pricing to ensure fair wages for drivers, while maintaining affordability for passengers.
A local medical student exemplifies the challenges. She drives from Kotturpuram to Nandanam metro station and parks her vehicle. She then takes the metro to Washermanpet. “I do not prefer buses because I have to walk from my residence to the bus stop and then wait for a bus. If I do this, I end up wasting time. Connectivity by bus is not that great,” she explained.
She prefers the metro over the local train (mass rapid transit system) for its cleanliness and air conditioning. Despite spending over Rs 2,000 monthly on her metro commute (including parking), she stated, “If I had access to AC buses, I would choose that as it will work out cheaper.”
Phase I of the Chennai Metro Rail Ltd (CMRL) project covered a 45.046 km network comprising two corridors: Corridor-I (Washermenpet to Airport) and Corridor-2 (Chennai Central to St Thomas Mount). This phase was later extended by 9.05 km from Washermenpet to Wimco Nagar.
CMRL has planned a Phase II expansion covering an additional 118.9 km across three corridors: Corridor-3 (Madhavaram to SIPCOT — 45.8 km), Corridor-4 (Lighthouse to Poonamalle Bypass — 26.1 km) and Corridor-5 (Madhavaram to Sholinganallur — 47.0 km).
CMRL has planned phase II expansion for a length of 118.9 km network. It consists of three corridors: Corridor-3 (Madhavaram to SIPCOT — 45.8 km), Corridor-4 (Lighthouse to Poonamalle Bypass — 26.1 km), Corridor-5 (Madhavaram to Sholinganallur — 47 km).
Investing in buses also makes strong economic sense. “The capital expenditure for a bus is much lower than investments in other rail-based modes. Given Chennai's climate, there's a clear need for more air-conditioned buses,” Jeyakumar of CUMTA told DTE.
Consequently, the absence of sufficient bus connectivity in these regions directly contributes to the proliferation of personal vehicles, especially two-wheelers, he added.
Further, metro reaches only 9 per cent of the population, explained Gadepalli. “The government will have to spend Rs 3,500 crore to get 3500 buses. This is the cost of building 7 km of metro and the government is laying 100 km of metro in phase II,” she said.
Venugopal AV, programme manager for Healthy Streets & Partnerships at ITDP India, an organisation that offers technical support on sustainable mobility initiatives in India, strongly advocated that metro development must occur in parallel with, and not at the expense of, bus network expansion.
Historically, the government’s priority has largely been private vehicles. "The budget is the best indicator of how important the issue is to the government," Gadepalli remarked. "While most financing goes into building flyovers and the metro, little to no money is allocated for buses, along with infrastructure for footpaths and cycles,” she added.
In the 2025 budget, for instance, phase II of the Chennai Metro Rail Project was allocated Rs 4,807 crore. The expansion of a 14.2 km four-lane elevated road along the East Coast Road from Thiruvanmiyur to Uthandi secured Rs 2,100 crore. To address Chennai’s escalating traffic congestion, fuelled by a significant surge in vehicular movement, the government also announced Rs 310 crore for a new flyover connecting Velachery Bypass Road to Gurunanak College Junction.
In contrast, the budget speech highlighted a Rs 3,600 crore allocation for the free bus rides for women scheme launched in 2021, noting that women save an average of Rs 888 per month because of it.
It also announced a Rs 1,031 crore allotment for 3,000 new buses, with 950 electric buses designated for Chennai. However, Jeyakumar cautioned, "While this is good, it is not adequate. We need to regularly add buses to meet the demand, and we need to plan now. We also need more electric buses and alternative fuel to reduce pollution.”
Venugopal asserted: "Expanding roads and building flyovers don't help ease congestion; they are short-term measures. Getting more buses on the road will help the city reduce congestion and pollution in the long term."
This article is part of our series on how India moves, which looks at the relationship between air quality and human mobility in cities and towns. This story is the third of the Chennai mobility series. Also read the first, second, fourth and fifth parts.