Challenge 1

Q:Why is a metro rail needed in countries with developing economy? What is your basic understanding on the differences between a conventional rail system and a metro rail system?
A: Metro rail is a good way to control environmental pollution and reduce traffic congestion. The main difference between conventional rail and metro is conventional rail will most likely travel on ground only. Whereas metros can be underground, overhead or on ground. Metros can also travel at sharper gradients as compared to conventional railway systems

Q: The course depicts the data regarding the operational and upcoming metro rail projects of India with reference to the statistics of latest by August 2019. Research and provide the current statistics of metro rail operations in India. At the end you can identify the necessary of metro rail transit system followed by you will be able to resonate/analyze the feasibility of metro rail to one’s own city.

A: Total length of runnning metros in India is about 700kms. An additional 550kms are under construction and 490kms are approved for the future as on date. DMRC has the longest running length of any metro in India with about 350kms of running lines.

Q: Why DMRC is the busiest metro in India. Apart from the points mentioned in the course video. You can find several interesting facts on the internet. Please research and provide your learnings.

A: DMRC has the longest running length of any metro in India with about 350kms of running lines. The immediate second is as low as 65kms in Hyderabad. Due to such a massive nature, it is the busiest metro in India.

Q: What are the components of a Metro rail? Explain briefly about the concepts of the components?

A: Components of metro rail are as follows:

Pile (foundation): the part of structure below ground is denoted as foundation.

Pier & Pier cap (substructure): The columns through whihch the loads of the metro and dead load of structure are transferred to the foundation.

Superstructure: The deck consisting of rails on which the metros ply.

Bearings: The load bearing components between the sub structure and the superstructure.

Q:Elevated metro or Underground metro which metro rail system shall be preferred? Justify your choice of the system.

A: Ideally, both are serving the same purpose. However, since metros are generally needed in already developed cities, underground metros are not preferred as diverting through the numerous existing utilities then poses a major challenge.

Q: What is a Design Basis Report (DBR)? In which phase of a project a DBR is prepared?

A: The DBR is the report which contains the principles of design for each of the components. The DBR is to be prepared at the start of each project. The DBR will also contain the brief method of execution to be followed for each component. DBR will include the basis for loading assumptions, design considerations etc.

Q: What is significance of a DBR of an elevated metro?

A: The DBR is the most important report for a metro. It will define the way the design is to proceed.

Q: In the planning of metro project, what are the chronology of activities before the construction?

A: The steps are as follows:

1. Topography survey

2. Utility survey

3. Alignment finalisation

4. construction feasibility

5. Span finalisation.

Q: What is topographical survey? Why it is necessary for the metro rail project?

A: Topograophy survey is identification of all object at the proposed metro alignment. For example: identification of houses, overhead elecric cables, ground profile etc. The topography is of significant importance because it will help in finalising the alignments with minimal impact to existing structures and utilities. The alignment can also be impact by the gradient which is to be achieved which will be reflected from the topography survey.

Q: What are the hindrances that could be there whilst planning to connect any to two stations in a city during metro construction?

A: The hinderances which could be faced during planning to connect any 2 stations during metro cosntruction are as follows:

1. Existing underground utilities (water, electric, internet etc).

2. Private land between the proposed stations

3. A religious structure which cannot be moved.

4. A nallah

5. Sewer lines

6. Existing highway to be crossed

7. Existing railway line to be crossed

Q: What are underground utilities which would be there existing under the ground level. Also mention some other utilities apart from the ones mentioned in the course.

A: Underground utilities may be some of the following:

1. Telecom cables

2. Electric cables

3. Sewer pipeline

4. Archeological site

5. Environmentally sensitive zone which may happen to limit the pollution (noise or otherwise) produced during construction

Q: Mention in detail about the solutions a designer would be suggesting as the challenges of underground utilities.

A: to overcome underground utilities, a designer may propose the following options

1. Obligatory span to cross the utility

2. Shifting of utility (not preferred as it is time consuming)

3. Adequate protection to the utility.

4. Having the utility from in between the piles to avoid damage

Q: What is known as feeding of U-girders and how it is launched during construction?

A: Feeding of U girders is generally done using SPMT (Self propelled modular transport vehicle). The U Girder will be launched by lifting it in place by 1 or 2 cranes. Feedign by SPMT vehicle would be till the feeding point which will be finalised based on requirements/ availability of crane and its capacities.

Q: What are advantages of precast girders in an elevated metro? Explain in detail about the how it is efficient over the cast in-situ girders?

A: The precast segments have many advantages over cast in situ girders.

In precast segments, the casting and curing are done in a precast yard. This casting is done parallel to construction of substructure and foundation which reduces time considerably. In cast in situ girders, the casting of the girder an only start after the concrete for the substructure has achieved sufficient strength.

The quality control and finish which is achieved in precasting is far superior to the cast in situ as the complete setup would be prepared at the casting yard.

In precast girders, the erection methodology is much simpler since it only needs to be placed at site. The requirements of enabling works at each location is eliminated only a precast yard setup is needed. The erection is also much faster as compared to erecting staging, casting, curing etc which is for cast in situ girders.

If a site is in residential area, the noise pollution for precast segments would be much less as compared to conventional cast-in situ girders.