The Hindu 21.12.2010
How far do flyovers help in easing traffic congestion?
Prime location: One of the flyovers on Anna Salai will come up near the new Secretariat.
CHENNAI: Speaking at a function here on Monday, Mayor M.Subramanian said that four new flyovers would be inaugurated within a year and Chennai will soon be christened as ‘flyover city'. Six flyovers were built in the city in the last four years. The city is going through a phase of expansion of elevated road spaces and the recent developments with regard to the two elevated corridors (one of them 1.9 km long and another a 2.9 km stretch) proposed on Anna Salai only reinforce this trend. But are the flyovers a genuine congestion reduction mechanism or is the city being converted into a concrete jungle?
The Chennai Traffic and Transportation Study had recommended the construction of eight elevated corridors in various parts of the city covering a total length of 77 km. Geetam Tiwari, Transportation Professor at IIT-Delhi, says that elevated corridors do not solve the problem of congestion as they only invite more cars on to the road. “Research shows that every time capacity expansion has taken place, in the form of extra road space for private vehicles, congestion levels go up within five years.
You cannot keep building lanes for cars. It is a never ending spiral. Western cities are getting rid of expressways and signal-free junctions. It is such an outdated idea,” she adds.
The increase in congestion is a well documented trend in the U.S. and is explained through a phenomenon called ‘induced traffic'. Texas Transportation Institute has studied congestion trends in 70 cities across the U.S. since 1982. By comparing data over the past three decades, TTI's annual mobility report for 2009 states that for every one per cent increase in new lane-miles, traffic volumes increased by 0.9 per cent in less than five years. “When road capacity is expanded near congested routes, drivers flock to the new facility hoping to save time. Also, the new roadways tend to draw people who would otherwise avoid congested conditions or take alternative modes to their destinations.
The result is an overall increase in the total amount of driving and the total number of automobile trips,” it concludes.
According to Ms. Tiwari, elevated corridors divide neighbourhoods, completely alter the landscape, increase vehicle kilometres travelled due to the illusion of speed and increase CO2 emissions. However, Krishna Murthy, Vice President, Wilbur Smith Associates, the consultants who prepared CTTS, said that due to a tremendous increase in vehicle ownership, a second-tier of roads is inevitable. “Additional road space is required even to run public transport buses. There will be a strong focus on public transport on the corridors which have been proposed along the Adyar River and the Buckingham canal,” he added.
But the charge is that attention to public transport is only superficial and bus lanes are being considered on the elevated corridors only to attract JNNURM funding. Speaking about the Anna Salai corridors, a senior Metro Rail official said that they will definitely affect Metro ridership.
“The rail system will initially start off as a low-patronage network. If road transport is going to be made easier, no one will use the Metro.”
