New Delhi: An unintended consequence of economic growth in cities is traffic congestion. Everyday, millions of vehicles across Indian cities are stuck in gridlock, but some cities seem to be more affected than others.

A Mint analysis of about 300 arterial roads across the country’s six largest metropolitan regions (New Delhi, Mumbai, Kolkata, Chennai, Hyderabad and Bengaluru) shows that on an average, the slowest arterial roads are in Kolkata and Mumbai, while Hyderabad and Chennai have roads with the highest average speeds.

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A 10km commute in Hyderabad takes 26 minutes on average. In Chennai and Delhi, it takes 29 minutes while the same distance takes 34 minutes in Bengaluru, 37 in Mumbai and 39 minutes in Kolkata. The average 10km urban commute takes 24 minutes, according to a World Bank study that calculated commute times across 154 Indian cities. In Singapore and London, the 10km commute takes an average of 21 minutes, show official documents.

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In India, official data on traffic and road speeds is often unavailable, and outdated when it is available. For this analysis, we identified arterial roads by referring to the Comprehensive Mobility Plan reports for these cities prepared by the respective municipal corporations and state governments. Using Google Maps data, we collected data on how long it would take to traverse these roads from end to end at hourly intervals from 4 August to 11 August this year. This weekly period represents a typical non-rainy week, and the average speeds in this week matched the “typical speed" ranges provided by Google Maps.

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The analysis suggests that morning commutes (8am -11am) are slightly faster than evening commutes (5pm-8pm). A 10km commute would take six minutes longer in the evenings on average, across all these cities.

Mahatma Gandhi Road in Kolkata (7.7km per hour) has the dubious distinction of being the slowest road considered in this analysis, followed by Sardar Vallabhbhai Patel Road in Mumbai (8.1 kmph) and the Kanakapura Road stretch from JP Nagar to Outer Ring Road (8.4 kmph) in Bengaluru.

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Kolkata has 11 of the slowest 20 roads across these cities, followed by six in Mumbai and three in Bengaluru.

Most of these roads are in the colonial-era neighbourhoods of these cities and are constrained by the fact that widening them is expensive. In Mumbai, the geography of the city itself is a constraint. A city with a narrow strip of densely populated land jutting out into the sea makes it more difficult to ease traffic pains.

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The fastest arterial metro road in India is the Outer Ring Road in Hyderabad, where the average speed is 60 kmph. The much-maligned Noida-Greater Noida Expressway is a distant second at 52.7 kmph, followed by the Chennai Outer Ring Road at 48.5 kmph.

Eight out of the top 10 fastest arterial roads are access controlled (toll roads), which helps limit congestion and improve speeds. While this seems to work, it is not a sustainable solution. Expressways—even access controlled—can eventually fill up, as the demand for private vehicles rise when more and wider roads are built, suggests urban transportation research.

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The most effective way to improve road speeds and reduce congestion is congestion pricing on key roads during rush hours, suggests research. Another solution is to build segregated bus lanes and encourage people to shift to public transportation modes. These solutions are yet to find support in India.

This is the first of a 10-part series on life in Indian cities.

Also Read: What data tells us about urban life in India