India Moves to Upgrade High-Density Rail Corridors: Key Expansion Approved

Why in News ?

The Union Government has approved the construction of third and fourth railway lines on the 32 km Badlapur–Karjat stretch in Maharashtra. This expansion strengthens a crucial segment of the Mumbai–Chennai High Density Network (HDN)—one of the busiest rail corridors in India. The move forms part of Indian Railways’ long-term plan to decongest all seven HDN corridors, which together form just 16% of the total network but handle 41% of all rail traffic. With rising passenger load and growing freight demand, expanding HDN capacity has become essential for safe, efficient, and future-ready train operations.

What’s in Today’s Article ?

• High Density Network (HDN): Concept & Features
• India’s Seven HDN Corridors
• Future Congestion Forecasts
• Need for Additional Lines
• Line Expansion & DFC Impact

About the High Density Network (HDN)

HDN comprises the railway stretches where both passenger and freight traffic are at saturation levels, leading to slower operations and increased delays.

• Total Indian Railways route-km: 69,181 km
• HDN route-km: 11,051 km (15.97%)
• Divided into 237 high-utilisation sections

Capacity Utilisation Levels on HDN

A healthy rail system should operate at 70–80% utilisation.

The HDN far exceeds this threshold:

Nearly 95% of HDN sections operate above the optimal limit.

Case Study: Karjat–Lonavala Section

• Length: 28 km
• Daily trains in each direction: 67
• Designed capacity: 40
• Utilisation: 167%

This illustrates the extreme congestion on the HDN network.

How the HDN Compares with the Rest of Indian Railways

National Rail Plan — 2051 Highlights:

• 45% of national routes run below 70% utilisation
• Only 1% of the total network crosses 150% utilisation
• Meanwhile, 14% of HDN alone exceeds 150%

This makes the HDN the most overstretched part of India’s railway system.

India’s Seven High-Density Rail Corridors

1. Howrah–Delhi (1,422 km)
   • Only two sections below 80% utilisation; rest saturated.
2. Howrah–Mumbai (2,039 km)
   • High congestion on Golden Diagonal; heavy freight–passenger demand.
3. Mumbai–Delhi (1,322 km)
   • Supported by the Western DFC; fewer sections above 150%.
4. Delhi–Guwahati (1,876 km)
   • 96% of the corridor above 80% utilisation; constrained by terrain & demand.
5. Delhi–Chennai (2,037 km)
   • Over half the corridor at 120–150% utilisation.
6. Howrah–Chennai (1,117 km)
   • Nearly 50% at 120–150% utilisation.
7. Mumbai–Chennai (via Pune, Solapur, Guntakal)
   • 90% utilisation between 80–120%; nearing saturation.

Future Congestion Projections

By 2051

• No HDN segment will operate below 100% utilisation
• 92% of HDN will exceed 150% utilisation
• Severe risk of operational slowdowns

By 2031 (Near-term Outlook)

• 50% of HDN → Above 150%
• 39% → 100–150%
• Only 9% → Within manageable limits

Without capacity expansion, HDN congestion will reach critical thresholds much earlier than 2051.

Line Expansion: The Core Strategy for Decongestion

With demand outpacing current capacity, Indian Railways has prioritised:

• Doubling
• Tripling
• Quadrupling
• Penta-lining and Hexa-lining

Recent Achievements in Line Expansion

However, the HDN load demands much faster expansion.

Role of Dedicated Freight Corridors (DFCs)

• Eastern DFC: Fully operational
• Western DFC: 96.4% complete

The DFCs are expected to divert large volumes of freight from HDN, helping free up tracks for high-speed and suburban passenger services. This remains one of the most transformative interventions for HDN decongestion.