New Delhi, Aug. 26 -- Indian Railways has embarked on an ambitious plan to quadruple capacity on its seven high-density routes, which together account for about 41% of the national railway network's traffic despite covering only 16% of its total route length.

Outlining the plan in an Instagram post, railway minister Ashwini Vaishnaw said the entire 11,000-km high-density network will be expanded to four tracks. The upgrade is aimed at easing severe congestion along the busiest passenger and freight corridors and preparing for future traffic growth.

The seven high-density routes identified by the railways connect major economic centres and metropolitan regions. They include Delhi-Howrah, Howrah-Chennai, Chennai-Mumbai, Mumbai-Delhi, Delh...