The Hindu 21.12.2010
How far do flyovers help in easing traffic congestion?
Ajai Sreevatsan
— Photo: M. Karunakaran
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 It is such an outdated idea,” she adds.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.”