Challenge 1

1. The metro rail system are needed in the main cities with dense population of developing countires in order to facilitate the movement of people with least disturbance to the existing traffic. This helps people to commute between thier homes and workplaces in efficient way. The metro system either bein elevated or undergorund creates least disturbance to the existing trasportation means like roads etc.

A conventional rail system connects various centers of urban areas or it can also connect two cities. In this system the rail tracks are laid on ground and considerable amount of land aquisition is required as majority of the track is laid on ground. The metro system is either elevated or underground. In both the cases the requirement of land is very less as compared to the conventional system. The elevated metro can run along an existing road on the median as the space required is only the width of pier which can easily be accomodated in the median of existing roads.

2. Operatinal Metros - Ahemadabad Metro, Bangalore Metro, Chennai Metro, Delhi Metro, Gurgaon Metro,

Hyderabad Metro, Jaipur Metro, Kanpur Metro, Kochi Metro, Kolkata Metro, Lucknow Metro, Mumbai Metro, Nagpur Metro, Noida Metro, Pune Metro

Total operation routes - 746 kms Under Construction - 490 kms Approved Routes 448kms Proposed Routes 1045kms

As further developments to the metros in India Metrolite and MetroNeo has been proposed. The MetroLite is proposed to connect cities with lower passesnger by use of Lite Rail system which can connect to the existing metro routes.

MetroNeo is proposed in 2/3 tier cities which is a tyre mounted system with OHE power supply system.

With existing combination of Metro, MetroLite & MetroNeo all the cities can be efficiently propvided the commute system for user. The challenges still remains in assessing the requirement of these systems based on the passengers for various routes in order to generate revnue and make all these system profitable.

3. DMRC is the busiest metro since there are no other rail networks in this region. Another reason is that Delhi not being a planned urban system the road system is not really effienct and this makes metro more effient and popular among public for transportationn and daily commute.

4. Component of Metro System- 

a. Superstructure - THe structure which connects two piers of metro rail system. This is a small span bridge. THe types are I-girders, Box Girders, U girders, Composite Girders etc. The type can be choosen based on the span.

b. Bearing - These are elements which connect the superstructure with substructure i.e. pier cap and pier. Types are Elastomeric, Pot PTFE, Spherical. The type can be choose based on spans. Elastomeric bearing are most effective and commenly used in metro.

c. Substructure - Pier cap and pier are part of substructure. These transfter the loads from superstructure to foundations. Types are circular pier, rectangular pier, Cantilever pier caps, portal system. Rectangular piers are more efficient. The circular pier can be more efficient in water chanels.

d. Foundation- These elements transfer the load to ground. These can be pile foundations, open foundation or well foundations

e. Abutments - These are also foundations which transfer the load to ground. The are generally provided at start and end of bridges and alos retain earth fill of ramps.

5. The type of metro system selected i.e. elevated or underground depends on various parameters which need to be considered in a given alignment and ground conditions. In cities or alignemnts with lot of buildings with deep foundations it may not be possible to go for underground metro. Also a weak underground soil condition with water tables etc can make underground metro uneconomical. In cities with good ground strata at shallower depth Elevated metro viaducts are preferred and can be economical. However in case of areas where land aquisition is proposed alignment is difficult underground metro can be a feasible and economical alternative.

6. Design Basis Report of a metro project which sets the standards, loadings, codes to be followed etc to be followed for the design of metro. It helps in standardizing the design procedure. It also helps in maintaining the uniformity in designs. With DBR in place any designer can design the structure in given metro project within given frame work as spcified in DBR. DBR is finalized in planning stage of project and it is finalized before start of detailed design process.

7. The DBR of metro project helps in mainting standard of design and maintaining uniformity in designs. With DBR in place any designer can design structure of metro project in given standards and specifications.

8. The Feasibility study for given metro project is carried out. In this few different alignments are studied to finalize the feasible and most economical alignment is finalized. The utility idenfication can then be carried out before start of construction. Utility mapping can be done before start of project, this is a proactive approach. The finalization of DBR is done and planning of construction in terms of timeline is done. After these details are in place the detailed design is done and then construction of metro is started.

9. The topography survey is assessment of ground condition in the alignment of metro line under consideration. This records the ground levels, location of existing roads, buildings water bodies. In this the water levels and bed levels of any water chanel in the alignment can be recorded. The details of any existing flyover etc crossing the alignment can also be recorded.

This data helps in planning the structures of the proposed metro line to avoid any obstructions, hinderances or operational clerance issues etc during the design stage itself.

10. Possible hinderances that can be there in a given metro alignment-

a. Places of Religious importance. b. Schools or colleges c. Industrial Buildings, Residential Buildings, hospitals d. Transmission Towers e. Water bodies, water chanels, f. Existing flyover, g. Existing railwayline

11. Underground utilities - Water pipelines, sewerage lines, gap pipelines, telecommunication cables, optic fiber cables, power cables, internet cables

12. Solutions to the challenges of underground utilities:

a. Utility survey and utility mapping (Proactive approach). This survey is carried out before start of construction. The alignment can be finalized to avoid hinderances or minimize hinderances with existing utitilities.

b. Utility diversion (Reactive approach) - In this case the utilites obstructing the foundation are diverted during construction of foundation

c. Change in Pile Arrangement - In order to avoid the obstruction with existing utility any pile of a typical pile foundation is shifted to clear the utility and relocated. With this pile arrangement can be non standard and irrelgular shape of pile can be formed and these are designed accordingly.

d. Catilever/ Portal Substructures - The structural arrangement of Substructure and foundation can be modifed to Portal or Cantilever type to avoid major utilities

e. Change of alignment- The alignemnt of metro can be diverted at location of hinderance with utilities.

13. Feeding of U-Girder is erection of U-Girders onto the pier cap i.e. at its final position. This can be done with a crane from ground or with a U-girder launching gantry. The girders are transported on trailers during night time. THese are then lifted with cranes and positioned on pier cap. They can also be lifted from trailer with help of launching gantry and placed on final location.

14. Advantages of Precast Girder - i. Faster construction ii. Better quality control at casting yard iii. Least distrubance to traffic etc at actual metro alignment.

With preacsting of girders we can cast the girder at casting yard and simultaneously erect the other girders at site. The use of precasting at casting yard helps in improving the quality of girders with controlled vibrating, curing etc. The staging etc which needs to be provided at site for in-situ construction can accomodate more space as well as require more material. This can cause hinderance to the traffic at site. With pre-casting of girders these issues related to in-situ construction are eleminated.