Stupidity of road widening - long articleDocument Transcript
Road widening – unnecessary destruction !
The next time you're on the road at peak traffic time observe this. There'll be a wannabe Michael Schumacher
who'll take off like a rocket at the signal, and you'll meet up with him at the next signal. You'll most likely meet up
with him at every signal over the next 10 km.
Why does this happen, even though he's driving faster than you ? This is because of the 'Schumi-Bang effect', a
scientific phenomenon caused by the interaction between Schumi's vehicle and Bangalore's roads. Here's the
When traffic signals are close to each other, your average speed depends on how long you stop at a signal
rather than on how fast you travel between signals. You don't have to be a transportation engineer to figure out
why. All you need is some primary school arithmetic skills.
Let's assume you and Schumi leave a traffic signal at the same time.
The next signal is ½ km. away, and is for a duration of 1.5 minutes (90 seconds).
The next signal turns red just as both of you leave the first signal.
Schumi travels at 60 km/hr., reaches the next signal in 0.5 minutes (60 km/hr means 1 km per minute, so half a
minute for half a km.), waits for 1 minute for the light to turn green.
You travel at 30 km/hr., reach the next signal in 1 minute, wait for 0.5 minutes for the light to turn green.
When the light turns green, both of you leave the signal at the same time.
This repeats itself signal after signal, and after a distance of 10 km. you're probably still abreast of each other.
In reality, many of the busier traffic junctions may have a wait time of 3 minutes (180 seconds), and in heavy
traffic you may have to wait for the light to turn green twice before you clear the junction. So the effect is even
I commute to work by bicycle. In an extreme example of the Schumi-Bang effect, I often keep abreast of a
Schumi at every signal almost the whole distance from my office to my home. At peak traffic time it takes me 1
hour from home to office by car, and it takes me the same 1 hour on my cycle. At every signal the cars and
motorbikes bikes reach before me and wait, and I eventually draw abreast of them.
Wider roads are the only solution, right ?
Widening a road enables you to travel faster between signals. Widening a single lane road to a double lane road,
for example, would double the speed between signals. As we've seen in the above example, however, doubling
the speed only doubles the wait at the next signal.
The problem is not the speed between signals. It is the wait at the signals.
The solution therefore is to reduce or eliminate the waiting time at signals.
We have living proof of this in Bangalore.
Sankey Rd. between the Golf Club and Mehkri Circle was notorious for traffic jams.
When the Cauvery junction underpass was built, the problem disappeared. A month after this the BBMP started
widening the Sankey Road between the Golf Club and Windsor Manor, from 2 lanes to 3 lanes each way. Traffic
signals at Windsor Manor and BDA junction were removed. Traffic from Bellary Road was diverted to Palace
Road. During this construction phase the road adjoining the golf course was actually reduced to one lane
because of the digging and debris. But guess what ? There was no difference in the traffic speed, even though
the road was narrowed instead of widened.
Hosur Road beyond the Silk Board was widened to 3 lanes. The traffic congestion should have disappeared, but
it did not. Again because of the Shumi-Bang Effect. Many stretches of the road are actually single lane because
of the construction of the elevated road. When you drive down the road now, you are coasting along at a
reasonable speed till you hit a traffic intersection. There's a traffic pile-up at every intesection, and only at
intersections. The problem again is not the road width, it is the intersections.
Sankey Road reduced to single lane during construction, near Hotel Meridien on Sankey Rd.
Showing no congestion at 6 PM, peak traffic hour, on a working day.
Traffic near Cauvery junction showing no signs of congestion at 6 PM, peak traffic hour, on a working day.
The BBMP knows about the Schumi-Bang Effect
In response to an RTI application dated May 22, 2008, the Asst. Executive Engineer, Special Cell for Subways,
replied with these details:
Before the Cauvery theatre underpass was built the average waiting time of traffic at the Cauvery theatre signal
was 180 seconds. The waiting time now, after the underpass was built, is 0 seconds.
Before the underpass was built the average speed of vehicles between Bangalore Golf Club and Mehkri circle
was 10 km/hr. The average speed now is 30 km/hr.
30 km/hr., by the way, is a good speed for inner city travel by international standards.
What we note is that this increase in speed was while Sankey Road was being widened, when the BDA junction
was not yet ready, and traffic was being diverted through a narrow single-lane side road in Kumara Park.
The obvious conclusion is that removing the traffic intersection at the Cauvery theatre by building an underpass
made the big difference, NOT road widening.
How do we avoid stops at intersections ?
Option 1 – Coordinated signals
Coordinated signals are a series of signals that work in such a way that vehicles can proceed through a
continuous series of green lights.
Let's now design a simple coordinated signal system for a 2 km. long main road on which there are signals every
0.5 km. and we want vehicles to travel at a speed of 30 kmph. Our main road has a single cross road at each
signal. That's 3 signals in all, plus the one at the start of the stretch.
Each set of signal lights has a simple controller that decides when the lights for the main and cross roads will
turn red, amber or green. The lights at each signal are independent of the others, and you get a red light for 1.5
minutes. After you leave signal 1, in the worst case you reach each signal just as it turns red.
Total travel time : 4.5 minutes to get past signal 4.
Here’s our new coordinated signal
To enable you to through all signals without stopping, each signal should turn green just as your vehicle reaches
it. When you leave signal 1, you reach signal 2 after 0.5 minutes, signal 2 after 1 minute, etc. Which means
signal 2, 3 and 4 should turn green 0.5, 1 and 1.5 minutes respectively after signal 1. To achieve this we just
need a slightly more complex controlling system that is connected to all 3 signals and controls them according to
Total travel time : 1.5 minutes.
We’ve increased the traffic speed 3 times without widening the road.
This is a simplified case, and actual conditions on the road are more complex. That's why, although you and I
designed this basic coordinated system with our knowledge of primary school maths, we need experts to design
the more complex ones.
In modern coordinated signal systems, it is possible to travel long distances without encountering a red light.
Traffic lights are centrally controlled by monitors or by computers to allow them to be coordinated in real time to
deal with changing traffic patterns. Video cameras, or sensors buried in the pavement can be used to monitor
traffic patterns across a city. The cost of such systems is a tiny fraction of the cost of road widening.
Option 2 – Underpasses or overbridges
We know what these are, and how they can help. Underpasses are of course preferable to overbridges in terms
of aesthetics - there is no ugly concrete sticking up in the air.
Coordinated signals are the better solution, and must be used as the preferred option wherever possible. They
require no extra construction and the resultant destruction of trees and buildings.
Then why are we destroying our city ?
Sankey Road has now been widened. The stretch from the Windsor Manor bridge till Cauvery Circle remains
unchanged, a two-lane road. When you come down from the Golf Club, at Windsor Manor the road is effecively
single lane just before the bridge. If you drive down this stretch the next time you'll see what I mean.
The width of a road is actually the width at its narrowest part, so Sankey Road is effectively single lane.
A beautiful line of trees has been cut down on either side of the road, the High Point police station has been
destroyed, the road has eaten into the golf course on one side and the properties on the other side. We've also
similarly destroyed St. John's Road in Koramangala and Bellary Road.
All completely unnecessary.
The problem was not the road width, and the solution was not widening.
How come the city's planners have not learnt from the Hosur Road experience ?
How come you and I, who have no expertise in transportation engineering or town planning, can understand the
Schumi-Bang effect but the people in charge of the city administration cannot ?
How come they never think of the intersections, and are hell bent on widening the roads?
How come they still cannot think beyond solutions like elevated roads going East-West, North-South and on
Mysore Road, a repeat of the totally asinine elevated road to Electronic City ?
How come the ‘experts’ are thinking of increasing road space instead of improving the utilization of the existing
HOW COME THEY DO NOT LEARN FROM THEIR MISTAKES ?
The BBMP now plans to widen 91 roads in the city, totalling 300 km. This is what the road widening is going to
cost the city:
1. Homes are going to be destroyed
2. Businesses are going to be destroyed
3. Going by past experience, the new roads will not have footpaths.
4. Scores of footpath vendors are going to lose their livelihood
5. Pedestrians are going to be even more marginalized than they are now
6. Children, senior citizens and physically challenged people will be totally unable to use roads
7. A lot of beautiful old buildings are going to be destroyed
8. Approximately 70,000 trees are going to be cut
9. Bangalore’s temperature will rise even further because of the addition of heat-trapping concrete and tar.
10. We as taxpayers are going to pay the money for all this, we as residents are going to suffer the
environmental consequences of all this
BBMP’s 10-point programme !
Bangalore as we know it is going to be non-existent. There is going to be a spanking new Bangalore, 'on par with
international standards' as our new CM says, soulless, devoid of history, devoid of trees, devoid of culture,
designed for automobiles rather than for people.
UNLESS WE THINK OF SOLUTIONS OTHER THAN ROAD WIDENING, NOW !
G V Dasarathi
The author is the Director of a software products development company in Bangalore.
As his personal contribution towards saving Bangalore’s environment, he cycles or takes a bus to work from
Sadashivanagar to Jayanagar every day, a distance of 15 km. each way.