Monday, 30th October 2017

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Branch by branch, tree maths

How long does it take to remove the giants?

By Subhajoy Roy in Calcutta
  • Published 24.05.20, 3:36 AM
  • Updated 24.05.20, 3:36 AM
  • 2 mins read
The travails of walking on a street that runs along Presidency University in Calcutta on Saturday. The tree was uprooted by Cyclone Amphan on Wednesday evening. Picture by Sanat Kumar Sinha

Trees, trees, trees…. They have dropped dead on many a road in Calcutta, some prostrate and some leaning on fragile support, crippling normal life, blocking efforts to restore power and becoming a millstone around the administration’s neck.

How long does it take to remove these unbending occupiers from the roads?

The arithmetic of tree removal follows, with the caveat that these are back-of-the-envelope estimates and do not claim to be precise figures.

Number of trees uprooted: 5,000, according to Firhad Hakim, the chairman of the board of administrators of the Calcutta Municipal Corporation (CMC).

Man-hours to remove one tree: 15 hours for a tree that is 2 feet in diameter and about 30 feet tall. A CMC official said five personnel and three hours are needed to remove such a fallen tree. But several trees are standing inclined, either hanging over a road or leaning on a building. Removing such a tree will take nearly 5 hours. If the tree is taller and the girth is wider, removal may take a full day.

Total number of man-hours needed to remove 5,000 trees: 75,000 hours, if 5,000 trees of 2ft girth and30ft height have to be removed. CMC officials say there are many trees in Calcutta that are about 100 years old and whose girth is much wider than 2ft.

Number of CMC tree-cutter personnel: About 110 with experience in cutting trees or removing fallen ones. The CMC is also using personnel from other departments who have experience in removing smaller trees. Combined, the number is around 160.

Number of man-hours per person a day: 8.

Total CMC tree-cutter man-hours available a day: 1,280 (160 x 8)

Manpower requirement for sweeping aside all the trees in one day: 9,375 trained personnel

Days that would have taken the CMC to clear the trees if it had not taken any extra help: Over 58 days (75,000 /1,280)

Will it take 58 days? The roads are likely to be cleared for vehicle movement and power supply will be restored much earlier.

That is because the CMC is using 32 pay-loaders, machines that have the capacity to push trees to the roadside within 30 minutes.

CMC officials said the primary target was to merely push the trees to the side and clear the path for power restoration. They said that clearing the road completely of any remnant of the fallen trees would take weeks, if not months.

Extra manpower drafted in by the CMC: A 60-member team from the National Disaster Response Force (NDRF) is helping the CMC remove the trees since Friday in Calcutta. More are at work in the rest of the state and at least 10 more teams are expected to join the effort in Bengal.

Also, five columns of the army (200 personnel at the most as the army has said each column in this case has between 32 and 40 personnel) and railway staff have been inducted in Calcutta.

With the additional hands, the CMC should be able to clear the roads faster.

The moral: Rapid action is the name of the game. Rapid coordination, rapid induction and rapid deployment.