Kolkata will soon have an underground Metro which will pass through tunnels many feet under the Hooghly. Commuters between Howrah and Mahakaran metro stations will be under the river for only about a minute when the metro train will pass through the tunnel at a speed of 80 km per hour. Looking back it was in 1984 that Kolkata had gifted India the country’s first Metro railway. Now, 33 years down the line, the City of Joy has added another first to India’s urban transportation landscape.
The East West corridor is another first. To start with, a transportation tunnel is unique to India because never in the history of the country has a tunnel been made beneath a flowing river. The internal diametre of each tunnel is 5.55 metre and the thickness of the wall is 275 milimetre. The distance between the two tunnels is 16.1 metre. There will be walkways in the tunnels for evacuation of passengers in case of emergency, an official said, adding it was a challenging task to dig tunnel under the river.
And there are a host of reasons to feel great degree of accomplishment for this project considering in terms of difficulty levels faced & challenges including boring under heritage buildings, seismic zone categorization of site, project social impediments of rehab plus business relocation, and ensuring right latest technology choice besides other factors. These issues are brought out here in the narrative.
The first transportation tunnel of India is ready and the second too is expected to be completed soon. The East-West Metro is scheduled to be operational by August/ December, 2019. This upcoming underwater metro train in Kolkata is one of the things the City of Joy has in common with London. A replica of London’s Big Ben has already become a landmark in Kolkata.
2017’s Good News First
India’s first underwater rail tunnel completed before schedule. A first in India, the two 520-metre structures are part of a 10.8 km underground stretch and are crucial to the East West Metro project.
Of ‘course the schedule is a revised one after work-restart, post 3-4 years ‘work stoppage'( see later in Narrative) . But what needs to be seen is that the time duration of the critical activity of 1st tunnel boring got completed in less than half the time allocated for it, which shows high productivity level achieved.
The deadline was July this year (2017). But the engineers and employees of Afcons Transtonnelstroy and Kolkata Kolkata Metro Railway Corporation Ltd, the two entities implementing the East West Metro have completed boring the country’s first tunnel under the Hooghly river for establishing metro link between Howrah and Kolkata.
Afcons Transtonnelstroy is an Indo-Russian joint venture. The machine was brought from Herrenknecht AG plant in Schwanau in Germany. The final TBM assembly in place was ready in April 2017.
The giant tunnel-boring machine (TBM) goes by the name Rachna and was deployed to dig the length of 502 metres underwater tunnel to run under the river.
Digging this tunnel was considered the most difficult job and an identified critical activity in the entire project. The job was completed in a time of one month and six days, about 50 days ahead of schedule. The project is built by Afcons Transtonnelstroy and implemented by KMRCL.
The entire project is 16.6 km long, out of which 10.8 km runs under the ground. Of this 10.8 km, 502 metres is under the water. The project connects Howrah to the west and Salt lake to the east.
Rachna starts off on New Year day
On April 14,2017 a day considered auspicious in many parts of the country as it marks the beginning of New Year, a gigantic Tunnel Boring Machine (TBM) began cutting deep inside the bed of the Hooghly river, commencing the construction of the first underwater metro tunnel in the country.
By the end of July, two tunnels running parallel will connect the twin cities of Howrah and Kolkata located on either side of the Hooghly. The tunnels are being dug at a depth of 30 metres below the earth’s surface and 13 metres below the riverbed.
The twin tunnels, about 520 metres long, are crucial to the much-awaited ? 8,900 core East West Metro project that will connect Salt Lake Sector V in the eastern part of Kolkata to the Howrah Maidan across the river.
Of the 16.6 km East West Metro route, 5.8 km is on an elevated corridor and 10.8 km will run underground. The 520-metre tunnels under the river are part of the 10.8 km underground stretch.
The twin tunnels, about 520 metres long, are crucial to the much-awaited ` 8,900 core East West Metro project that will connect Salt Lake Sector V in the eastern part of Kolkata to the Howrah Maidan across the river. Of the two underwater tunnels, one is for Howrah bound Metro trains; the other is for Salt Lake bound trains.
The underwater tunnel is an important landmark in progress towards completion of the second phase of Kolkata Metro expansion called the ‘East West Metro Project’ that has to connect Howrah station in the west with Salt Lake Sector V in the east.
The underwater tunnel is an important milestone for the ‘East West Metro Project’ because this underwater mode on completion will significantly reduce traffic congestion on the streets of Kolkata the moment it gets operational. The Howrah station witnesses major traffic of daily commuters coming from neighbouring districts to work in the different parts of the metropolis.
Besides the second phase of metro will also connect with another major railway terminus Sealdah that brings daily passengers from North 24 Parganas, South 24 Parganas and Nadia districts of the state. These districts also satiate much of the agricultural and fish appetite ofthe city.
KMRCL officials said that 250 workers will be working on the tunnels on a daily basis. The target is to place 10 concrete rings a day, each of which measures 1.5 metres. Project engineers said that at this rate they should be able to complete the 520 metre twin tunnels in next three months, that is, by end June.
Once this is achieved, Kolkata would have got project on ground but People, however, shall have to wait at least perhaps until 2020 to ride a Metro train passing below the Hooghly river.
However, KMRCL has plans to throw open a near 7 km stretch from Salt Lake to Phoolbagan, off Sealdah station, by end 2018. The stretch between Phoolbagan to Howrah Maidan via Sealdah shall have to wait for the work to get completed.
The optimistic estimate of first tunnel completion has come to the actual too! “As per our optimistic estimate by the end of May or the first week of June this year, the first under-river tunnel of India will be complete. One tunnel-boring machine is already under the water, and the second machine will also start working by the end of May.
Both the tunnels will be complete by July,” Satish Chandra, Managing Director of the Kolkata Metro Railway Corporation Limited (KMRCL) told The Hindu.
TBM 2, which too had gone deep into the bed of the river, and progressed a distance of 100 metres.
Explaining the nature of the soft clay soil under the riverbed, Mr. Chandra, who is also Assistant General Manager, Eastern Railways, said the two TBMs could not work simultaneously. “One machine goes ahead and the second follows;they cannot simultaneously,” Mr. Chandra said.
(See Figures 3 & 4).
The diameter of the two tunnels running across the river is 5.5 metres and the distance between the two tunnels will vary at different places 16.1 metres under the river, 18 metres at the Howrah station, and 13 metres at the Howrah Maidan (from where tunnelling started in May 2016).
“The entire credit for completion of the work much before scheduled deadline goes to the 250 odd engineers, technicians and workers, who have worked day and night to complete the task. On an average we have dug 35 to 40 metres every day, following which the digging of the entire tunnel length of 520 metres was completed in little more than a month,” a KMRCL officer said.
“Considering the pace at which we completed the most difficult task of creating the underwater tunnel, we hope to meet the deadline of final commissioning,” the KMRCL official said. The final commissioning of the project commissioning of the project is expected by December 2019, following which it will be operational.
The stretch of 16.6 km will have 12 stations, six of which will be under the ground, while the remaining six stations will be on elevated tracks.
Since the beginning, the project was held up several times mainly due to land allocation, slum relocation and route alignment problems among others.
The project was originally slated to be completed by 2012. It was first postponed to 2015 and finally to December 2019.
The narrative now on wards will be on the project Aim, project technology, project’s history, cause of delays, rescheduling & recovery, Issues of Heritage conservation -Risks Avoidance- due diligence ‘for Best Step Forward!.
Project Aim – A Winners-All, Citizen-Friendly Design
The primary aim of the EastWest Metro corridor project is to deliver to city a reliable travel mode that is time cum cost effective with reasonable comfort level. Such mode also has to be seamless from end to end. The East West metro corridor design precisely attempts to make such travel in Kolkata possible. This no doubt has been a daunting task as it means a movement right across the heart of Kolkata and to connect cost & comfort effectively two of the city’s most populous areas. To do so the corridor has been planned to drastically cut down on travel cost and time. To give an idea of this lets consider normal commute time of at least an hour and a half and multiple modes of transport to travel between the extremities of the city at peak hours on a weekday. In comparison with the operation of the East West Corridor, the commuters would find themselves reaching their destinations in a fraction of the time they take today. Besides they would do so reliably in air-conditioned comfort.
An efficient connection between Howrah and Sealdah stations, which between them cater to about 24 lakh passengers a day, has been a dire necessity for every commuter for whom the daily trip into and out of the city at these two stations is nothing short of a nightmare. The East – West Corridor finally puts an end to this ordeal.
Next plus is that the East-West Metro Corridor will provide the Kolkata commuter a seamless way to travel thereby eliminating the multi mode dilemma from station – bus stand- auto / taxi stand .
Yet another hopeless prospect of a Kolkata-Howrah journey is crossing Hooghly. For this the East West metro is a welcome alternative offering uncompromised efficiency of travelling more than half kilometer below the water surface across the Hooghly!
Technological precision and expertise has been put together for the project to deliver a state-of the-art metro line for travel under the Hooghly to cross-over from Howrah to Kolkata. , KMRCL at the planning stage itself decided to minimize discomfort to commuters by adopting appropriate technologies of a level like those of the Eurostar. (Connecting Paris and London)
The reinforced concrete segmental tunnel linings have a thickness of more than a quarter of a metre and are caulked with a composite gasket of neoprene and hydrophilic rubber to seal the tunnel from ingress of water. it is claimed that this technology is a innovative first in India while being a rare venture world wide.
The underground portion of the corridor has adopted the latest boring process, rather than the top down cut and cover process (which citizens have experienced during the construction of the North-South metro), sparing the citizens inconvenience and traffic snarls.
And to bore the tunnels, “Earth Pressure Balance” Tunnel Boring Machines procured from Germany. These mammoth TBMs (almost 2-story high) operating many metres under earth surface bore upto 15 metres a day, excavating up to 500 m³ of earth a day, while for life & activities on city surface it is business as usual unaffected by the frenetic tunnel boring going right beneath them!
(See Tech Data, Highlight Figure 3 & 4 and Route Map Figure 5 and Key Features that mark this Project )
The tunnel has been made 30 metres under the river, just a few metres away from the famous Howrah Bridge, built last century to connect Howrah and Kolkata.
There are not even roads under a river in India and this technological marvel for the country will have trains moving in and out of the platform every two and a half minutes.
Satish Kumar, managing director of KMRCL remarks ‘It will be connecting two main terminals: Howrah and Sealdah each of which has a footfall of about 10-12 lakh passengers per day,’ adding that : ‘These types of tunnel-boring machines, which we call ‘earth pressure balancing tunnel boring machines, have been used for the first time in eastern India’.
Interestingly the construction of this tunnel has meant 10 lakh tonne of mud being dug out. The entire stretch of the first tunnel, 16.6 km long, is finished while the second tunnel has yet to be completed.
Of the entire length,
– 10.8 kms is underground and
– Around one kilometre is beneath the river at both ends.
(See Figure 6 & 7 for an idea of Work progress)
‘For tunnelling below the river, the water tightness, waterproofing, and the de-sign of gaskets were the major challenges, because the tunnel is being constructed for a service of 120 years, so we cannot afford any water leakage during service,’ said Kumar.
Moreover Tunneling work cannot be carried out for too long and therefore much of the preparatory work was already done for almost a year prior to machines and equipment being shifted to the location for final implementation and execution of the plan.
The seismic angle had to be kept in mind since Kolkata falls in seismic zone 3. Accordingly material and design used has to cater to keep tunnel protected against the eventuality of quakes.
‘Uniqueness’ to the East West Metro also comes from the use of the standard gauge which is the latest technology. This latest technology has been used to ensure that the tracks have sharp curves, keeping in mind that this tunnel passes under a lot of heritage buildings (see sn.9 Key Features).
Delays – Causes, Course Corrections, Chan-ges, Solutions- Implementation
Why Delay? Work stops 2012! Though construction projects are plagued with in-numerable hassles including land acquisition, here too they were progressively attended to. But Work at the line’s Howrah Maidan had stopped 3+ years ago sometime in 2012 due to the contractor, a JV of Afcons-Transtonnelstroy, refusing to start work owing to persisting land acquisition issues in Kolkata’s Bowbazar-BBD Bagh area which the state government took no interest to resolve.
As such, the contractor moved key equip-ment to its Shibpur shed and even sent some off to Chennai to assist in building the UAA-01 (Egmore to Washermentpet) and UAA-05 sections (Shenoy Nagar – Thiru-mangalam) of the Chennai Metro project.
What Solution? All stakeholders agree to New Alignment in Aug.2015 & start work Nov. 2015! With the new alignment chalked out & frozen in August 2015 and the vital all agencies agreeing to it, construction workers returned to the Howrah Maidan site in November 2015. The work was kick-started at the site in order to launch the Tunnel Boring Machines (TBMs) towards Howrah station. The work thus resumed and readying of machine assembly started.(See Description of New Route of Metro as per August Agreement).
The E-W Corridor Back on Track
How? BBD Bagh Minibus Stand & Esplanade’s Tram Tracks to Make Way for Kolkata’s East-West Metro.
Yes! With a new route/alignment finally chalked out for Kolkata’s east-west metro line, the mini bus stand at BBD Bagh (Dalhouse Square) will temporarily make way for a new station at Lal Dighi (Mahakaran). Similarly, the tram tracks just south of it at Esplanade will make way for a new station at Esplanade which will form an interchange with the existing north-south line’s Esplanade station.
As per the new route, the line’s underground section will run from Howrah Maidan Howrah Lal Dighi (Mahakaran) Esplanade Mullick Square Sealdah Phoolbagan to Subhash Sarovar. Out of this, tunneling for only the twin tunnels between Subhash Sarovar Phoolbagan Sealdah sections has been completed. The old route would have connected the Sealdah station with Central station (and formed an interchange with the north-south line), but land acquisition issues prompted the line to be realigned to the new route mentioned in bold.
This is a map of the new route (See Figure 8)
As already mentioned, the Lal Dighi (Mahakaran) Metro station will come up at the location of the mini bus-stand at BBD Bagh (Dalhouse Square). In 2017, instead of seeing the bus stand, you’ll see the underground station’s box! Traffic Police officials and Transport Department officials have been holding meetings with bus operators to rehouse the affected bus operators. They have been given 3 options:
1. Move to other bus stands in the city,
2. Set up a temporary shed near Vidyasagar Setu and
3. Drop passengers and return to the originating point with a brief halt at the mini-bus stand.
Similarly, the Tram tracks between BBD Bagh and Esplanade will make way for the East-West line’s Esplanade station. Initial barricading and utility shifting work on this sectionwas to follow suit with the TBM from Sealdah towards Esplanade was scheduled to be launched in the last quarter of 2016. Once the line is operational the mini-bus stand and tram tracks are expected to return back to their original locations.
Back to Work – Lowering Cradles to seat Kolkata Metro’s TBM at Howrah Maidan
One of the four cradles approximately weighing 25 tonnes and about 8.2ft in length, was lifted from the ground by a crane and laid at a depth of around 59ft. This cradle would hold a portion of the tunnel-boring machine while the other three which get two days later would take balance load. The portion of the machine that will rest on the 4 cradles weighs around 250 tonnes And that’s the weight of a 100 elephants! (see Figure 9).
Thus, Digging Work on the tunnel on the Howrah Maidan-Sealdah stretch of East-West Metro also resumed on Friday 8th Jan’16 after being stuck for more than three-and-a-half years. Railway minister Suresh Prabhu signaled the start of work at Howrah Maidan during a programme at Howrah station.
An engineer of Afcons Infrastructure, the firm executing the project on behalf of Kolkata Metro Rail Corporation (KMRC), said drilling would start once the work of fixing the entire machine gets over by the first week of March.
“The entire project from Salt Lake’s Sector V to Howrah Maidan should be ready by 2018,” Prabhu said.
Outer diameter: around 21ft. See the circular groove marks on the concrete wall. As per an engineer the inner diameter of the tunnel would be around 18ft. “Once drilling starts, the tunnel-boring machine is expec-ted to reach the Hooghly’s edge, around 500m away, in about four months,” he said.
Minister Prabhu said it would take 20 months to complete the tunnel till BBD Bag and merge it with the tunnel from Phoolbagan.
Tunneling work on the Howrah Maidan-Howrah station was then marked to start in March 2016 once all the TBM’s parts are lowered and assembled. The plan was that it would take anywhere from 3 to 5 months for the TBM to reach the Howrah station which lies on the edge of the Hooghly river.
At Howrah Maidan, the tunnel would be built at a depth of 59ft from the surface (See Figure 11). The tunnel under the Hooghly would be at a depth of 66ft (the approximate height of a six-storey building) from the riverbed. The depth from the water surface would be 154ft 3ft shorter than the height of Shahid Minar. The depth of the tunnel in the Tollygunge-Dum Dum section ranges between 24 and 30ft.
According to Suresh Prabhu the 9 km first phase of the East-West line from Salt Lake Sector V to Sealdah should be scheduled for becoming operational in June 2018 while the 6 km second phase from Sealdah to Howrah to be made operational by June 2019.
Attention! – Understanding the E-W Metro (River) Tunnels
What: Twin East-West Metro tunnels to connect the proposed Mahakaran station on the Calcutta side with the terminating station at Howrah Maidan, a distance of 2.9km.
Where: On the Howrah Maidan side.
Speed gauging: When One of the boring machines first progressed 90 metres towards the river. The second machine had just started boring the other tunnel.
When: The completion target was est. as June 2017. Actual achieved be-fore June.
To get idea of how movement from shaft to tunneling and mud excavated sent up, see Figures 11, 12, 13, 14 & 15).
– Each of the two machines has been built to sustain atmospheric pressure four and a half times more than at ground level, a key requirement for drilling tunnels through a riverbed.
– The machines are fitted with powerful cutters to bore their way through land and then the riverbed.
– In one month, the first machine had progressed 90 metres towards the Hooghly. Officials of the Kolkata Metro Rail Corporation said the speed of the tunnel borers would gradually be increased to around 200 metres in a month on an average.
– Parallel tunnels, each 5.5 metres in diameter, are bored through Howrah Maidan en-route to the Hooghly.
– Precast concrete segments are placed to lay the shaft the moment the boring machine drills underground and re-moves mud to create a portion of the passage.
– Near Howrah Maidan, the depth of the tunnels is such that the roof of the concrete structure will be about 14 metres underground.
– As the tunnels proceed towards the Hooghly, they will slope and go deeper under the river. At one point, the roof of the tunnel would be about 30 metres underground, according to the plan.
– The existing north-south Metro has only one tunnel where passengers on two trains running parallel are visible to each other as they pass.
– The East-West Metro will have interlinked stretches every 250 metres where both tunnels will be on view.
– The idea is to enable passengers aboard a train going through one tunnel to escape to the other in the event of an emergency.
– Since it isn’t technically feasible to have interlinked stretches along the Hooghly riverbed, two escape shafts are being built at either end of the river route.
– Excavated mud being brought out by an engine pulled wagon at the Howrah end. By the time both tunnels are ready, two lakh cubic metres of mud would have been carved out to create the passage for trains to run underground and through the Hooghly riverbed
The issues to be addressed
Though since beginning, the project was held up many times (mainly due to land allocation, slum relocation and route alignment problems among others), with most solved as cited it may finally be over essentially by December 2019.
Residential buildings and Business es-tablishment temporary relocation or rehabilitation or intervention for strengthening is needed in some areas. For heritage Buildings due diligence with technical confirmation on their sustainability had to be seen.
Hurdle being faced by the East West Metro Project is the threat the tunnelling work may pose to three heritage buildings in Kolkata. The Currency Building, an Italian structure that served as one of first banks of the country, and two 19th century Jewish monuments the Maghen David Synagogue and the Beth-El Synagogue stand close to the Metro tunnels.
As per the existing rules, construction and mining operations are prohibited within 100 meters of protected monuments but the Currency Building is 24 metres away from the Metro’s alignment, and the Beth-El and Maghen David synagogues are at a distance of about 17 metres and 9.8 metres respectively.
After the issue was raised by the Archaeological Survey of India, an expert committee from the Indian Institute of Technology, Kharagpur, was constituted to look into the matter. The committee said there would be no “ adverse affect” on the protected monuments.
And the centre seems to be determined to do ‘All that can be done’ to arrest any more delays. These may include anything Even Ordinances!!
Centre may take ordinance route to clear E-W decks
The Union ministry of culture is likely to promulgate an ordinance to remove hurdles in the way of the ambitious East-West Metro project.
The ordinance will change the rules that prohibit construction of infrastructure projects in the vicinity of protected monuments.
“Instead of waiting for the AMASR (Amendment) Bill, 2017, to be tabled in the monsoon session of Parliament in July, it makes sense to have an ordinance passed to get the project going.
The proposed ordinance will replace the Ancient Monuments and Archaeological Sites and Remains (AMASR) Amendment Act, 2010. A draft on these lines, prepared by the culture ministry, has been sent to the law ministry for vetting.
The development brought relief for the Kolkata Metro Rail Corporation (KMRC), the implementing agency of the ` 8,900-crore East-West Metro project, which stared at an uncertain future after it failed to get the go-ahead from the Archeological Survey of India (ASI).
With the tunnel-boring machine, which can’t be stopped from tunneling, reaching close to the Kolkata bank of the Hooghly, the fate of the entire project became uncertain.
It was found that the AMASR Act must be amended to allow the tunnel pass within 100m of heritage buildings in the BBD Bag area Beth El synagogue, Maghen David synagogue and the Currency Building. The imbroglio got a breather as the Centre proposed a bill to amend the heritage protection act.
Sources said the proposed ordinance will redefine “public work” into Section II of the act and make provisions for projects like the East-West Metro. The decision on the ordinance comes after much persuasion from the ministry of railways. “The ministry of culture has scrutinized the existing act to strike an appropriate balance between importance of heritage sites and public welfare,” said a source.
Evacuation of Vulnerable Buildings – A boost for work along Brabourne Road
Finally, there’s some good news for city’s East-West Metro project. There is fresh hope for construction of the Metro line along Brabourne Road after the project got stuck due to issues over vulnerable buildings in April’17. Kolkata Metro Rail Corporation (KMRC) authorities had difficulty in convincing residents of vulnerability of buildings necessitating vacating their houses for safety’s sake. Majority of the residents of these century-old buildings had refused to move out of their houses.
The KMRC had identified nine risky buildings along Brabourne Road which would pose a threat for the Metro construction once the Tunnel Boring Machine (TBM) reaches the Kolkata end.
The refusal by these residents necessitated the formation of a joint team comprising the KMRC, Kolkata Municipal Corporation (KMC) and Kolkata Police for an inspection of these buildings. The first joint ins-pection has taken place but the residents don’t want evacuation.
Members of the joint inspection team recently started with residents of 42 Strand Road, which is a three-storeyed building hou-sing over 40 people that has been given an unsafe tag by the KMC building department.
KMRC officials accompanied by KMC building department personnel, Kolkata Police officers, along with Afcons (construction firm) officials talked to residents of the buildings about the urgency for an evacuation plan before construction work for East-West Metro begins along Brabourne Road. KMRC and KMC officials expressed satisfaction over the discussion. “We are happy we could convey our message to the people and make them understand the necessity of evacuating the building for the sake of Metro construction. At the same time, we could also assure them we will not only provide alternative shelter to them but necessary repairs would be made in case the construction causes any damage to the structure of the building,” a KMC official said.
The joint team members had to do same visit residents of buildings at Raja Woodmont Street The KMRC needs to evacuate more than 300 people from four buildings in the area. “Four buildings at Wood-mont Street are included among the nine insecure buildings which the residents need to vacate once the TBM machine starts operating in the area,” said an Afcons official.
Being on Track
The local opinion of a Kolkata resident and perhaps those arriving for business here is that it’s a good project because the Metro is the cheapest and the fastest form of transport, used by a large number of people which will also hopefully ease traffic on the surface. And it will be very beneficial in connecting people from all over Kolkata.
For the Railways, besides the tunnel under the Hooghly river, drilling work is going on for the seven-km-long under- sea route of the Mumbai-Ahmedabad rail corridor to ascertain soil condition for India’s first bullet train path.
Being on track Railways can offer Passengers the thrill of travelling under the sea at a maximum speed of 350-km-per-hour, another first in the country, near Thane in the upcoming high-speed train project connecting the two metropolis. Many such events are on Track in near future!
The author leads our Delhi bureau. An Engineer and qualified ADR professional (NALSAR alumnus), Sadagopan Seshadri has been a senior Contract Management Professional in large national & International Companies. His domain experience is in Building Products, Cement plants and Mega Power project execution. He has been an expert visiting faculty and univ. examiner for Contract Management at the SSAA, IP University, New Delhi. Being passionate about Environment Energy & Sustainability he has now turned to sustainable development Themes He is vocal with his views on these areas through his writings.
He can be reached at: email@example.com