The Centre has approved the construction of a third and fourth line on the 32-km Badlapur–Karjat section in Maharashtra, marking a major boost to both Mumbai’s suburban network and the Mumbai–Chennai High Density Network (HDN). The decision is significant as the stretch forms a critical part of the 1,238-km corridor, one of Indian Railways’ most heavily utilised routes connecting Mumbai with Chennai via Pune, Solapur, Guntakal and Arakkonam.
The latest approval aligns with Indian Railways’ long-term strategy to ease congestion across all seven High Density Networks. Though these corridors constitute just under 16 per cent of the national rail network, they carry 41 per cent of the total rail traffic, making them essential for both passenger mobility and freight movement. With demand rising steadily, increasing line capacity on these saturated routes has become indispensable.
The High Density Network comprises heavily used passenger–freight corridors where trains run well beyond their designed capacity, resulting in persistent congestion and delays. Out of the Railways’ 69,181 route-km, the HDN spans 11,051 km or 15.97 per cent. According to the Planning Directorate of the Railway Board, only 4.6 per cent of this network operates below 80 per cent of its maximum capacity. Nearly one-third is operating at 100–120 per cent utilisation, another 29 per cent at 120–150 per cent, and over 14 per cent at more than 150 per cent. In total, 213 out of the 237 sections on the HDN are functioning at above 80 per cent utilisation.
One of the starkest examples of saturation is the Karjat–Lonavala section, immediately after the Badlapur–Karjat stretch. Here, an average of 67 trains run each way daily against a maximum capacity of 40, resulting in a utilisation level of 167 per cent. These figures far exceed the national averages highlighted in the National Rail Plan, which shows that only one per cent of the entire Indian Railways network operates above 150 per cent capacity.
The HDN spans all four regions of the country through seven major corridors, including the Howrah–Delhi, Howrah–Mumbai, Mumbai–Delhi, Delhi–Guwahati, Delhi–Chennai, Howrah–Chennai and Mumbai–Chennai routes. Most of these corridors are severely congested. For instance, 96 per cent of the Delhi–Guwahati corridor operates at more than 80 per cent capacity, while nearly half of the Delhi–Chennai and Howrah–Chennai networks are running at 120–150 per cent utilisation.
The National Rail Plan projects that congestion will intensify dramatically in the coming decades. By 2051, none of the HDN sections is expected to operate below 100 per cent capacity, and 92 per cent of the network may run above 150 per cent utilisation. Even by 2031, half of the HDN is projected to operate at more than 150 per cent of its capacity, with only nine per cent likely to run within the ideal range of 70–100 per cent.
To address this, the Railways has accelerated its line-doubling and capacity enhancement works. In 2021–22, 1,983 km of doubling and tripling projects were completed, followed by 3,185.5 km in 2022–23, 2,244 km in 2023–24, and more than 2,900 km in 2024–25. The Dedicated Freight Corridors are also playing a key role: the Eastern DFC is fully operational, and the Western DFC is 96.4 per cent complete. These corridors are expected to divert significant freight traffic, easing load on the HDN and improving passenger train operations.
Currently, the HDN comprises 250 km of single-line sections, 8,113 km of double lines, 2,040 km of triple lines, 625 km of quadruple lines and 23 km of penta or hexa lines. The National Rail Plan recommends upgrading the entire Howrah–Delhi and Delhi–Guwahati corridors to triple lines, and …
