When Prime Minister Narendra Modi inaugurated the Kochi Metro in mid-June, he said that 50 other cities are interested in similar rail systems. This is good news as public transportation is more sustainable than personal cars or motorbikes. It uses up less road space, consumes less fuel, emits fewer pollutants and causes fewer road fatalities. It is for this reason that the National Urban Transport Policy, adopted in 2006, recommended investments in public transport rather than in transport policies that promote greater personal vehicle use. There is a range of public transport options available, including standard metro rail systems and buses, and newer variants such as light rail, bus rapid transit and trams. Each has pros and cons in terms of costs, passenger load, environmental degradation and the ease of making route and scheduling changes in response to demand. City planners should assess the number of passengers who would need to be transported before deciding on the most expen...