Inplant training experience on Chennai Metro Rail Project

I am studying III year civil engineering. I have completed my In-plant training on Chennai Metro Rail Project. It was guided by L&T company. I would like to share some of my knowledge on Metro Rail here. Surely,it would be useful to everyone.

Project Profile

The Metro Rails runs through a distance of 45 km. In which 24 km run through underground and 21 km run through elevated platform. In this the underground metro project is divided into 5 packages namely UAA-01, 02, 03, 04, 05. The package that we visited was UAA – 04. This package includes 5 stations, they are

  • Egmore station

  • Nehru park station

  • KMC station

  • Pachaiyappas College station

  • Shenoy Nagar station

These 5 stations are connected by underground tunnelling. These stations belong to corridor II of phase I Metro Rail Project. The distance between these stations are given below:

  • Egmore station to Nehru Park station - 950 m

  • Nehru Park station to KMC station – 575 m

  • KMC station to Pachaiyappas College station - 900 m

  • Pachaiyappas station to Shenoy Nagar – 950 m

The packages were split and given in the hand of certain companies to take over the construction work by the GC. The construction Process in this Package (UAA-04) was undertaken by LARSEN & TOUBRO LIMITED (L&T) and SHANGHAI URBAN CONSTRUCTION GROUP (SUCG) and it is monitored by CMRL.

Casting work of segments at Thiruverkadu

On the first day of our In-plant training we were taken to thiruverkadu where the casting work of tunnel segments was studied.
Casting is a manufacturing process in which a liquid or molten material is poured into a mould which is a hollow shaped object and then it is allowed to get solidified .This solidified part is only known as casting and then it can be broken out from the mould and so the process is completed.


  • Each ring consists of 5+1 segments.

  • Smallest segment (+1) is called as the key piece.

  • Last two (4th&5th) segments are called as counter keys.

  • Remaining segments are called as standard keys.

  • Width of each segment is 1.2 m.

  • The segments are tapered to a definite angle of 19mm.

  • These are pre-casted by using moulds at the workshop.

  • Also these segments are provided with holes for interlocking with their own segments and their nearby segments.

Tunnel segments after casting process


  • Each ring is made up of six segments.

  • Internal diameter of the ring is 5.8 m.

  • Radius is 2.9 m.

  • Thickness of each ring is 275 mm.

  • Per ring is of 6 cubic metres.

  • Weight of each ring is 16 tonnes.

  • The width/Length of each ring is 1.2 m.

  • The total number of rings for 4.08 km is 5700.

Procedure for Ring Casting:

  • The mould should be cleaned.

  • Application of shuttering oil is done or application of releasing agent.

  • Fabricated reinforcement placement is done by using EOT.

  • Concrete of M50 grade is poured into the mould by means of some carriers which has a setting time of 30 minutes to 3 hours.

  • Excess concrete is cut off from the mould.

  • After this steam curing is done in order to accelerate the setting of concrete.

  • Curing compound locks the water.

Final tunnel image

Cycle time:

  • The cycle time is the time taken from the first activity to the last.

  • Per day 2 to 3 rings were made.

  • Each ring takes about 10 hrs for its completion.

The time taken for each process are as below:

  • Demoulding and cleaning – 45 min.

  • Gage fixing – 1 hr.

  • Concreting – 45 min.

  • Initial setting – 3 to 4 hrs.

  • Top finishing – 30 min.

  • Steam curing – 4 hr.

  • After completion of work, these rings are lifted by using crane and transported to the site location safely.


On the second day we were taught about the slab details. Each slab is of width 19.5 m and length 228 m.The three types of slabs are:
concourse and roof slab images

  • Roof slab

  • Concourse slab

  • Base/platform slab

  • A 6m vertical clearance is provided at each level

  • Waterproofing is done

Construction of slabs:
Roof Slab:

  • Excavation up to a depth of 3m to 6m and the roof slab is cast.

  • Length - 228m

  • Thickness - 800mm

  • It is at the level of the road

  • The roof slab is coated with primer and made to dry for 8 hrs.

  • Then water proofing membrane of thickness 4 mm is done.

  • And then a PCC work of M15 grade is done above which the sand is backfilled.

  • Temporary decking is provided for traffic movement

Concourse Slab:

  • At 6m depth below the roof slab the concourse slab is cast

  • Thickness - 800mm

  • Serves as the ticket counters

  • Stairs, escalators and lifts are provided

Base Slab:

  • At 8m depth below the concourse slab the base slab is cast

  • Thickness – 1m

  • Tracks are laid and passengers board trains

  • Stairs, escalators and lifts are provided

Needle Grouting:

  • The size of the needle is 200 mm.

  • The diameter of the needle is 10 mm.

  • A resin is injected through the needle which is inclined at an angle of 45 degrees to the diaphragm wall.

  • This resin on reaction with water starts swelling and therefore arrests the intrusion of ground water into the tunnel.

  • This technique is used in slabs also during top down construction.


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Guest Author: Anguraj22 May 2015

How you get an opportunity?

Guest Author: pradeep27 May 2015

Hello Rajesh , really it was a very useful information for me . The information which you have explained above about the metro rail project is really good. I have acquired some of the knowledge about the metro rail construction.
Please do me a favour , I am also a civil engineering student now I've completed 3rd year . I would also like to go for the metro rail construction in chennai , Can u please say me how to apply for the inplant training. I request you to inform me immediately as soon as possible.

Guest Author: thanikachalam25 Aug 2015

Hello Rajesh thank for your wonderful article I request you to tell me how to apply for the inplant training program in Metro Rail. I am presently studying 3rd year in civil engineering.

Guest Author: harshit12 Apr 2016

Rajesh, thank for your wonderful article! I request you to tell me how to apply for the inplant training program in Metro Rail. I am presently studying 3rd year in civil engineering.

Guest Author: swetha03 Jul 2016

Rajesh, thanks for your wonderful article! I request you to tell me how to apply for the in-plant training program in Metro Rail. I am presently studying in 3rd year in civil engineering.

Guest Author: liya08 May 2017

CodeBind technologies provides inplant training in Chennai for all students like ECE, CSE, IT, EEE, ICE, etc

Guest Author: Pragadeeswaran23 Dec 2017

This is very useful information. Can you please say me how to apply for the in-plant training in the metro train project?

Guest Author: sran29 Mar 2018

Thanks for the information. could you suggest me how to make an application for metro in-plant training.

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