planning of kolkata metro railways
TRANSCRIPT
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Planning of Kolkata metro railway system
Prasun Roy Chaudhuri (2011MT 0130)
Gautam Kumar Jha (2011MT0132)
Nandan Kumar (2011MT0134)
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Planning of Kolkata metro railways
Historical background
The city was designed by the British and could not cope up with the conditions of modern
traffic increase. The streets were getting congested with overflow of cars and personal vehicles
causing traffic jams. The city needed a new type of mass transport which could transport the
people easily, fast and efficiently.
There were different commissions set up to check for the feasibility of sub urban train lines.
The ideas included over ground circular railways light tramways and other forms of
transportations.
There were reports by different commissions to up over-ground circular railways. The circular
railway though set up couldnt ease the traffic congestion in the heart of the business district
since the circular railways couldnt be constructed too close to Esplanade and Park Street area.
The 1st
commission to consider the underground metro system was the FRENCH METRO
MISSION in 1949. Though the Mission did express some concern about the construction of
underground tunnels due to bad soil condition in Kolkata.
The French Metro Mission had proposed a two electrified routes from Howrah maidan to
Sealdah (3.91miles) and another from Paikpara to Kalighat (7.14 miles). The Mission also
proposed the creation of a passenger terminal in heart of the business district.
The report proposed that both the route to be electrified and the ultimate capacity of the
system be 50,000 passengers per hour.
The mission reports was not considered then due to the lack of funding and also during that
time the circular railways construction was given preference.
Some of the major world cities with metro railways
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Cities Population
(in millions)
Kilometers of
rapid transit line
Year of
operation
London 7.0 410 1863
Paris 8.5 240 1900
New York 17.2 370 1868
Moscow 8.0 182 1935
Tokyo 24.3 190 1927
Kolkata 9.0 10 1984
As we ca n se e from the abov e chart mo st of the mo dern ci ti es in the wo rld pref er
mass transport system in the form of metro railways.
Historical background of Kolkata metro
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Kolkata was first Metro Railway system in India and was designed on international standards
to ferry people to the business district quickly, efficiently and comfortably all the while keeping
the transportation cost low.
Idea was conceived in 1949 by Chief Minister. During the French Metro mission the
underground rapid transport RTS (Rapid Transport System). But during that time the plans
couldnt be materialized due to the lack of funds.
Metropolitan Transport Project (MTP) setup in 1969 under Ministry of Railways and this body
was given the authority to look over the construction of the metro project.
Work of first line sanctioned in 1972. Surveys and construction work started in 1973-
74 and completed in 1995 in 6 parts, first in Oct, 1984. DumDum (Airport) to Tollygunge a
distance of 16.4 Km. 15 stations entirely underground was planned while the terminal stations
were on the surface.
Delay due to availability of funds, u/g utilities, court injunctions, no availability of vital material.
There was a lot of opposition to the project since it was a new concept in India and also since a
lot of the roads were to be dug up and traffic was to be diverted during the constructional
phases.
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The proposed route map of the metro
The north south line shown in green is already constructed while the blue line is
under construction.
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Aspects considered when planning was done
a) Geographical featuresb) Climatec)
Drainage and flood levels
d) Seismic datae) Geological featuresf) Traffic conditionsg) Predicted passenger entry
Geographical features
The land is flat and clayey in nature. Clay is not a good soil for tunnel construction since it hashigh water content and very low strength thus making the construction site and tunnel very
prone to collapse and flooding.
Most of it alluvial deposits due to the river delta formation. Since the work site is in close
proximity to the river this added to the risk of water seepage.
The maximum elevation of the land is 9m with average elevation of 6m from sea level. This also
meant that the water table was high and the construction had to be shallow such that it did not
penetrate the water table and case a disturbance in it.
The land mass on the east and western sides are tidal marsh land. Thus the route on the east
and west couldnt be constructed underground.
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Climate
The climate is tropical. Hot and humid for most of the year. Due to close proximity to the river
the humidity of the city is high.
There are distinct seasons. There is a hot season followed by the monsoons and a dry cold
season. But the cold season is short and the monsoon rains are not uniform sometimes
excessive rains causes flooding (in 1984). This caused the site to fill up and construction came to
a halt.
Some data about the climate of Kolkata
Highest ever recorded temperature 43.9C in June,1924
Lowest recorded temperature 6.1C in January, 1962
Highest rainfall in 24 hours 369.6mm (28-9-78)
Highest humidity 100%
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Drainage and flood levels
Drainage is a major factor in any underground construction since is prone to flooding. This is a
very important factor since during construction there were concerns for site flooding and in
some cases the trenches were deeper than the main drains which are supposed to take away
the water. So pumps were kept handy to pump the water out to the main sewers.
The drainage is done by sewer system which is managed by Kolkata Municipal Corporation. The
water from the site was pumped into the main sewers which carried the water to the
Bidyadhari river and out to sea.
Due to heavy rains and flooding the metro station entry is kept at 500mm above the highest
flood point at the location. So that during operation the water doesnt flood into the stations
and tunnels from the entry points.
Water due to seepage into the tunnels are collected in reservoirs in the tunnel midsections and
pumped out by the use of SUMPs.
Due to the planning for drainage and flooding the metro system has never been flooded. Even
so there are 2 SUMPs provided at each stations to cope up in case of emergency.
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Maximum flood level at a few major station sites
Name of the station Level of crown of road
(meters)
Highest flood level
(meters)
Tollygunge +4.98 +5.16
Kalighat +4.26 +4.36
Rabindra Sadan +4.17 +4.65
Park Street +5.10 +5.10
Chandni Chowk +5.7 +5.7
M G Road +3.96 +4.64
Syambazar +5.43 +5.53
Dumdum Jn Elevated station
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Seismic data
India lies in an earthquake belt and many regions are subjected to frequent earthquake thus
the seismic monitoring is very important before construction. Although tunnels are considered
much safer than surface buildings but earthquake can cause collapse and is dangerous during
the construction phase.
Kolkata falls in seismic ZONE III with and horizontal seismic coefficient of 0.04 to 0.06. Though
Kolkata has minor tremors it is never in the dangerous level.
Geological features
Preliminary soil investigation was done by 50m borehole at 500m. The core got from thesewas sent to the lab for primary investigation. Detailed investigation was done by sinking 30m
borehole at 100m interval.
The primary strata were found to be Gangetic alluvium no borehole has been able to penetrate
beyond it. The top soil is soft except for the upper layer which is firm and stiffness increases as
depth increases.
The soil was layered with patches of hard and silt and sandy river deposits. The soil just below
the upper layer was of rotten timber and clay. The topmost layer is compact but the sub layers
were much less harder but hardness increases with depth. The bedrock is so deep that that till
now no excavation has reached it.
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The strata can be divided into the following classification
Top stratum
(reduced level Approx in meters)
Highest Lowest
Stratum I Light brown sandysilt
Ground level generally at 0.00
Stratum II Grey or dark silty
clay with semi
decomposed timber
+0.25 -11.5
Stratum III Bluish grey silty clay -8.0 -17.5
Stratum IV Brown sandy silt -13.0 -22.0
Stratum V Brown or grey clay -15.0 -35.0
Stratum VI Brown or light
brown silty fine
sand
-30.0 -45.0
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Strata details
Stratum type Natural moisture
content
Cohesion
C
Kg/cm2
Angle of friction
degree
Stratum I 30 0.28 0
Stratum II 55 0.28 0
Stratum III 30 0.56 0
Stratum IV 26 to 32 0.42 15 to 33
Av 32
Stratum V 22 to 25 1.05 0
Stratum VI 29 to 30 -- 40
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Traffic conditions
The major factor for the construction of the metro was to ease the traffic flow in the business
districts of Kolkata.
The chart below gives the people inflow via public transport into the business
district
Type of
transport
In bound traffic Outbound traffic
Morning peak
hours
Daily total Evening peak
hours
Daily total
Tram 48,019 3,91,230 43,247 3,79,661
Bus 36,278 3,44,685 33,247 3,39,986
Total 84,294 7,35,915 76,970 7,19,647
From the above chart we can see that a huge volume of people use the public transport to get
to the business district. Since these public transports are all surface based increasing the
number of these will also increase in surface congestion.
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Few of the causes for deteriorating traffic conditions in Kolkata
1. Road area is not adequate to support the amount of traffic we have.2. Uneven footpath allocation and utilization.3. Some areas have 6 to 10 feet wide footpath where no people walks.4. 80% of Kolkata footpath is occupied by hawkers.5. Our habit - we do not like to walk on footpath. Even where there is no hawker on
footpath people prefer to walk on road.
6. All the road sides are used for parking for Taxi, Private cars, School bus etc.7. Not enough or none at all parking spaces available.8. People walking on road never want to abide by the signal.
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Predicted passengers entry in metro railways after its construction
Stations Predicted passenger entry perday in 1990
Dum Dum 1, 23,000
Syambazar 1, 43,000
M G Road 1, 02,000
Esplanade 1, 23,000
Park Street 51,000
Kalighat 1, 71,000
Tollygunge 1, 96,000
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System and parameter that was considered during construction
The transit system is chosen to be a double rail system and mostly underground as there was
no space for over ground space for construction of that magnitude. The construction was cut
and covers but was carried out in phases so as to cause minimum disturbance to traffic.
The 1st
transit line was for Rapid Transport System was to be constructed between DumDum in
the north and Tollygunge in the south. This too was constructed in phases.
The stations are approximately 1km apart and are located at places of public interest where
maximum passengers can be got most efficiently.
After the route was fixed the main thing used in the system the coach dimensions other factors
like moving dimension and fixed dimensions are calculated.
This was used to predict the required clearance for peak hour traffic.
Based on these calculations and dimensions the fleet of cars was decided.
This helped in calculation of peak hour traffic and gave an average idea of the dimensions of
the stations and platforms based on the peak rush hour passengers.
In case of Kolkata metro the signaling system of international standard is considered such thattrains can be run at close intervals to each other.
The frequency of the trains are scaled up or down during peak hours and off peak hours thus
increasing passenger carrying efficiency.
The rake size that was chosen for Kolkata metro has the following dimentions
Length over couplers 20.3 meters
Width 2.74 meters
Height 3.70 meters
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Station stop time of the trains
Station stop time is an important factor to be planned.
The station stop time should be such that it gives enough time for passengers to de board and
get aboard the train while now allowing the train to idle in the platform for too long.
The optimum time was predicted to be 30 sec per station while the average speed of the train
35km/hr with a top speed of 80km/hr.
A central control room was to be set up to monitor the trains from a central location and
control the signaling system.
The trains were also provided with public address system so that the next stations can be
announced and people can get off more easily and also to announce the closing of the doors.
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Features of Kolkata metro
General features
Gauge 1676mm (5-6)
Length
Centre to centre of the termini 16.450km
Total length 17.185km
Length of connection to car depot 0.877km
Total including car depot 18.062km
Number of station
Underground stations 15
Elevated 1
Surface 1
Distance between stations
Average 1.028km
Maximum 2.151km (DumDum to Belgachia)
Minimum 0.597km (Chandni Chowk to Central)
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Expected traffic when full section is opened
Average weekday traffic
1. Year of opening 1.32 million2. 5 years after opening 1.53 million3. 12 years after opening 1.73 million
One way peak hour volume
1. Year of opening 51,000 passengers2. 5 years of opening 60,000 passengers3. 12 years of opening 67,000 passengers
Average tr ip le ngth 6. 80 km
Train frequency during peak hours
1. Year of opening 24 pairs/hr2. 5 years after opening 28 pairs/hr3. 12 years after opening 31 pairs/hr4. Theoretical 40 pairs/hr
Number of trains per day
1. Year of opening 3112. 5 years after opening 3743. 12 years after opening 429
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Rolling stock and traction
Number of coaches to be procured
1. Year of opening 2322. 5 years after opening 2643. 12 years after opening 304
Train composition 8 coaches total 163 in length
1. Driving coach 22. Non driving motor coach 43. Trailer coach 2
Class of accommodation One class
Carrying capacity1. Driving motor coach 42 sitting 259 standing2. Non driving coach 48 sitting 278 standing3. Trailer coach 48 sitting 278 standing4. Total 8 coaches 372 sitting 2186 standing
Coach dimension1. Length (buffer to buffer) 20.40 m2. Width (outer to outer) 2.74 m3. Height (above rail level) 3.70 m4. Maximum axle load 17.00 tones
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Acceleration
1. Maximum 1.1 m/sec22. Jerk rate 0.75 m/sec2
Deceleration1. Service 1.1 m/sec22. Emergency 1.3 m/sec2
Speed
1. Maximum 80 km/hr2. Schedule 30 km/hr
Station stop time 30 sec
Traction system
A. Voltage 750v DCB. Current collector 3rdrail (return running rail )C. Braking electro dynamic and pneumaticD. Motors
Bhel 93KW 338v 310 A
NGEF 160KW 675v 265 A
Controls rheostatic and thyristor/ GTO
Door operation electro pneumatic
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An older metro rake
Picture taken by Railfan Siddhartha Mukherjee
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A new AC rake
Picture taken by Railfan Saugata Sengupta at Park Street station
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Ventilation system parameters
Main parameters
1. Max temperature (in stations) 30 C2. Max temperature (in tunnels) 32.8 C3. Max relative humidity (stations) 87%4. Max relative humidity (tunnels) 77%5. Max air velocity (stations) 3m/sec6. Max air velocity (tunnels) 2.5m/sec7. Air changes in station 29 times per hour8. Air changes in tunnels 12 times per hour
The ventilation system is provided both at the platforms and in the tunnel mid sections
of the tunnels. The ventilation system is divided and air is blown into the platform from
both ends via ducts. There are ducts running below the platform which helps to remove
the heat from the traction motors when the train stops at the station. The mid section
fans are also used to exhaust the air from the tunnels.
Air conditioning units are also provided at each station to keep the station air cool
during the hot seasons.
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Civil engineering concerns and planning
Method of construction
1. Reinforced concrete box 13.874 km2. Driven tunnel with C.I or R.C 1.232 km3. Elevated length 1.584 km4. Surface trough 1.372 km5. Total 18.062 km
A box section
Picture taken at Syambazar station showing the box section and the diaphragm
wall with the ventilation fan access on the right
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A circular tunnel section driven using compressed air method
Starting of the circular bored tunnel section just after Syambazar station towards
Belgachia side.
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Platforms
Length All platforms are of the same length 170m
Height above rails 1.03m
Type and width
DumDum 2 side platform
5.0m & 7.0m wide
Central One island platform
8.26m and 2 side ones
with 4.13m
Park street 2 side platform of 5.5
m each
Tollygunge 2 side platform 6.0m
wide
Other stations Island platform 10.26m
and 8.26m and 1.03m
Depth of station
Underground station
Depth of station from ground level
Maximum at central 12.854 m
Minimum at park street 6.920 m
Elevated station
Height above ground 6.975 m
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Box tunnel dimensions
Box section
Tangent track 8.19 X 4.64 m internal
Curved track 200m radius 9.04X4.15 m internal
Bored tunnel
Single track 5.10 m internal dia
5.50 m external dia
Horizontal alignment
Minimum radius of curvature
In block section 200m
In stations 1000m
Gradient abstract
Steepest grade
In running line 1 in 50
In connection to depot 1 in 25
Longest continuous length 0.726km
of gradient in running line
Level line longest length 0.627km
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Vertical alignment
Gradient
a) Max running line gradient 2%b) Min track gradient between station 0.3c) Max track gradient in coach depot 4%d) Min track gradient at station 0.2%e) Max track gradient at station 0.2%
Vertical curve
Min radius of vertical curve 2000m
Curve abstract
Ratio of total curve length
Tollygunge to Dumdum 38.84%
Dumdum to Tollygunge 38.47%
Average amount of curvature per Km
Tollygunge to Dumdum 388 m
Dumdum to Tollygunge 384.7m
Track structure
a) Main tracks are ballast less and consists of 60kg rails with elastic fastenings on concretebed.
b) In the depots the tracks consists of 44.61 kg/m or 90R rails on sleepers resting onballasts.
c) 1 in 10 points and crossings are on wooden sleepers resting in ballast in running linesand 1 in 8 for car depot.
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Constructional planning
Most of the underground tunnels were done by using cut and cover method.
In cases where the tunnel had to go under a water body like near Syambazar shield tunnelingwas done.
Shield tunneling was also used to tunnel under the Chitpur rail yards where the rail yard
couldnt be closed for construction.
Constructional considerations
- Traffic Diversions- Environment- Washing of rake and Low Noise of Equipments- Utilities diversion- Safety Independent safety organization of Contractor/GC- Barricading & controlled Access of sites- Risk analysis before activity starts- Exhaustive Instrumentation
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Tunnel dimensions
The next step of planning was to predict the tunnel dimensions.
The factors that were to be considered while planning tunnel dimensions are the size of carsand moving dimension and maximum permissible speed of the rakes.
The dimensions were decided by Indian Rlys Schedule and also from world practices.
The tunnels are chosen to allow rakes of 4.64 m in width and on the curved section the rakes
have a tolerance up to 5.515m.
The overall average internal dimension of the tunnel is 8.190 m X 4.640 m.
In case of bored tunnel the diameter is 5.1 m for single track.
The platform width is approximately 6m on average with maximum width of 10m and height of
5.20m from the floor.
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Cut and cover details
Majority of the tunnel was under main city roads there was a problem and traffic had to
be diverted and also utility like gas, power, water and telephones had to be diverted for
construction.
The majority of the utility was supported by struts and other support above the
construction site while work continued underneath them.
H-piles where sunk to support the brackets which in turn held up the struts to support
the utility lines. Most of the excavation work was done manually and was thus very
labor intensive. The gas lines had to be turned off or redirected during the construction
and excavation phase.
During the cut and cover design the main construction was done by constructing adiaphragm wall and then the excavation took place.
The walls were approximately 10 m apart where there were normal parallel tracks and
about 19m apart where there were stations.
The excavation depth ranged from 12 m to 14 m.
The diaphragm wall was held in place by struts of 3 to 5 levels depending on the depth
and nature of the soil at the site.
Different types of cut and cover used
Diaphragm walls 12.687 km
Sheet piles 0.365 km
Sheet piles with timber 0.684 km
Open cut 0.937 km
Most of the construction was done with diaphragm wall constructio n
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Machinery used to erect one section of wall per day
Batching plants 1 No Dumpers 3 No Bentonite mixing units 1 No Vertical spindle type Bentonite pump 2 No (P & H) Tata 320 crane 2 No Grab Heavy 2 No Form tube 600 mm diameter 2 No Tremmie pipes 200 mm diameter with funnel 2 No Bailer 1 No Chisel 1 No Power Winch 1 No Tripod 1 No Scrapper 1 No Mobile Bentonite tank 1 No Welding plant 2 No Gas cutting unit 1 No
These machines were used in the construction of only one section of the wall per
day.
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Details of the diaphragm wall
The main excavations for the diaphragm wall was done by use of GRABS mounted on
the cranes and were guided by telescopic guides. The length of each panel varied from 3
m to 6 m and the depth varied from 16 m to 23 m. The excavated volume was filled with
Bentonite slurry to prevent the collapse of the excavation. Then reinforcement cages
were lowered and concrete of grade M-200 was poured into the excavation sealing the
bottom of the cage. As the concrete is pumped in more and more the Bentonite is
pumped out and is poured back in tanks for recycling and reuse.
Some places where there had to openings made for ducts and passenger exits hollow
cages were used which used a framework of beam and ducts for exposing the areas to
be cut later.
Problems faced in diaphragm wall construction
Excessive cut The walls are constructed with a tolerance limit of 1 to 60 mostly the
excavation went smoothly but in area near Bhowanipore (Km 12.50 to Km 13.50) the
shapes of the walls are irregular due to the bad soil condition there were internal
collapses and sometimes due to over grabbing of soil. Again at Km 13.10 to Km 13.80
due to clayey soil and sand the soil could not hold its shape it collapsed into small
pockets. Thus the walls in these locations are irregular and they had to be laboriously
chiseled into shape.
Jamming of end pipes There were steel cylindrical pipes made of sheet steel. These
were to hold the cages in position when there would pouring of concrete. They were to
be removed as the concrete settles in. in some case the pipes got jammed and concrete
had to be poured in the pipe cores and they were made integral part of the diaphragm
walls.
Incomplete grabbing to the full length In some areas grabbing to the full length was
unsuccessful due to the soil conditions. The grabbing had to be stopped when a
compact sand layer was encountered. To overcome the problem jets were used to
loosen up the sand but in most cases it was unsuccessful. The diaphragm walls were
prematurely terminated and could not achieve full length.
Segregation of concrete The concrete poured had heavy segregation and also there
were blank pockets in the diaphragm wall. These problems were seen when excavation
was being done and then concrete was poured into the blank pockets to seal them up.
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Delays, risks and other problems faced by the project
1. Delay in Approval of Detailed Project Report (DPR)2. Land Acquisition risks3. Design Risks4. Technology Selection Risks5. Approval and Permit Risks6. Financial and Investment Risks7. Political Risks8. Environment Related Risks9. Geo-technical Risks10.Major / Minor Accidents during Execution11.Unforeseen Heavy Rains12.Force Majeure Risks like Flood, Fire, Earthquake etc.13.Labor Agitation and Strikes14.Inflation Risk15.Delayed Payment from Client16.Delayed Payment to Subcontractor
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Land acquisitions problems
Since the metro was mostly built under the city the land acquisition was not a problem for the
main running tracks.
The land to be acquired for the construction of depots at Tollygunge and Dumdum was a issue
but was sorted out.
Land was also needed to be acquired for the construction of the station exits and ventilation
shafts.
The land acquired from different agencies and parties
Land in acres
Eastern railways 9.52
Ministry of defense 1.702
CMC & Baranagar municipality 74.81
Govt of Bengal relief and rehabilitation
department
18.37
Tollygunge club 21.56
Private parties 178.00
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Land acquisitions near DumDum for car shed construction
Nearly 261.00 acres of land was acquired for the construction of the shed near dumdum
station.
Most of the land belonged to Eastern Railways and was a part of the track embankment.
The rest of land belonged to CMC and Baranagar municipality and was used as a
dumping ground.
Land acquired for contracts depots
Location Area
Talla park 6258 sq m
Desbandhu park 2823 sq m
D N Mitra Square 2040 sq m
Southern park 4098 sq m
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Damage to surrounding structures and their precautions
Settlement of ground during cut and cover is a common occurrence. It is a common
practice to strengthen old building and monuments before the start of the construction.
In the Tollygunge Esplanade section there were stray cracks due to soil settlement.
In Bhawanipore area where the buildings are of old masonry and shallow foundations
there were large cracks.
Metro authority was responsible for these repairs.
Soil settlement problems
1. Subsoil profile and properties of soil.2. Shape and depth of excavation.3. Type and stiffness of support system.4. Sequence and method of construction.5. Time of construction
In Kolkata the major factors were
1. Spacing between the struts (specially 1st & 2nd)2. Time effect
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Preconstruction precautions
Before the excavation was started all inside the chosen zone of influence masonry
buildings over 40 years old were surveyed and put under observation.
Plumb lines and other monitoring equipment were installed at convenient locations to
monitor sinking or leaning of buildings.
Whenever they showed any signs of cracks the building was repaired and the soil was
grouted.
Station aesthetics
Stations were designed so that they do not look dull and monotonous.
The flooring is marble in most stations while the pillars are colorful tiles and designs.
Murals were put up at different places to have a lively atmosphere.
Historical painting replica and other lightings brighten up the atmosphere in the
stations.
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Bibliography
1. The metro railway working literature2. Electrical maintenance manual of Kolkata metro3. Figures and plans of Kolkata metro4. Pictures of the rakes provided by Railfans Saugata Sengupta and Siddartha Mukherjee5. Wikipedia.org6. Kolkata metro railways official web site