Understanding the Placement of Metro Rail Systems: Why Some Are Not Underground

Why are some metro rail systems not underground? The primary reasons for this decision revolve around costs, accessibility, and urban planning. Let us delve into the factors that influence the placement of metro rail systems and explore the advantages of surface and elevated rail systems.

Cost Considerations

The most significant reason for not constructing a metro rail system underground is the high cost of tunnelling. In city centres, tunnelling may be the only viable option due to the premium price of land, but this is not always the case in suburban areas. Land availability, both on the surface and on embankments, offers alternatives that may be more cost-effective.

In existing cities, adding metro rail systems much later than the initial stages of urban development can make land acquisition even more challenging. Business areas and densely populated regions often create conflicts, leading to higher costs and longer processes. Therefore, the choice of surface or elevated construction becomes a practical and financially viable solution.

Accessibility and Urban Planning

At-grade stations offer an easier access point for people, especially those with mobility challenges. The construction of surface and elevated rail systems, while potentially more expensive upfront, can be completed more quickly because most of the work is at ground level. Elevated stations can be built without the need for extensive excavation, reducing construction time and costs.

The construction of metro rail systems at grade also aligns with urban planning goals. As metro tracks are added to accommodate growing populations, accessibility to key areas such as markets, residential areas, institutional buildings, and major hospitals becomes crucial. This leads to the placement of stations near these locations, integrating the metro rail system with existing urban infrastructure.

Advantages of Surface and Elevated Rail Systems

Surface and elevated rail systems have several advantages, particularly regarding traffic management and accessibility. These systems do not conflict with existing traffic systems, which minimizes disruptions and delays. This is why you often see elevated or overground metro lines in areas where underground construction is not feasible due to space constraints or the cost of acquiring land.

For example, in Delhi and Kolkata, which have older urban infrastructures, the construction of metro rail systems was not feasible underground due to lack of available space and the need to pass through developed areas. As a result, these cities opted for surface and elevated rail systems to integrate with their existing traffic patterns and provide easier access to various parts of the city.

Case Study: Delhi and Kolkata Metro Rail Systems

Delhi and Kolkata, two major metropolitan cities in India, have experienced the implementation of metro rail systems at different stages of urban development. Delhi got its first metro line in 1998, while Kolkata established its metro system in 1984. The choice of surface and elevated systems is clear, as these cities had to navigate through densely populated and commercially active areas, making underground construction too costly and impractical.

In Kolkata, the Yellow Line (Netaji Subhas Chandra Bose Road Metro Line) is partially underground but also features several overground sections. The construction of these elevated sections was necessary due to the significant space constraints in the Chandani Chowk area. Similarly, in Delhi, stations like Shastri Park, Seelampur, Yamuna Bank, Kirti Nagar, and Green Line, and the Kolkata Metro station at Mahanayak Uttam Kumar, were constructed at grade level to ensure accessibility and reduce costs.

Conclusion

The construction of metro rail systems involves careful consideration of various factors, including cost, accessibility, and urban planning needs. While underground systems offer several advantages, they come with significant financial and logistical challenges. Surface and elevated systems provide an alternative that is more cost-effective and easier to implement in existing urban environments. As cities continue to grow and evolve, the choice of rail system placement will remain a critical aspect of infrastructure development.