Darjeeling Himalayan Railway (DHR)
- Location: West Bengal (New Jalpaiguri to Darjeeling).
- Length: ~88 km
- Gauge: Narrow gauge (2 feet or 610 mm)
- Altitude: From ~100 m (New Jalpaiguri) to ~2,200 m (Darjeeling)
- History: Built between 1879 and 1881.
Nilgiri Mountain Railway (NMR)
- Location: Tamil Nadu (Mettupalayam to Udhagamandalam / Ooty)
- Length: ~46 km
- Gauge: Meter gauge (1,000 mm)
- Altitude: From ~300 m to ~2,200 m
- History: Line opened in 1908.
Kalka–Shimla Railway (KSR)
- Location: Haryana to Himachal Pradesh (Kalka to Shimla)
- Length: ~96 km
- Gauge: Narrow gauge (2 feet 6 inches or 762 mm)
- Altitude: From ~650 m (Kalka) to ~2,076 m (Shimla)
- History: Opened in 1903.
