BG meaning in Regional ?

A broad-gauge railway is a railway with a track gauge broader than the 1,435 mm (4 ft 8+1⁄2 in) standard-gauge railways.

Broad gauge of 1,524 mm (5 ft), commonly known as Russian gauge, is the dominant track gauge in former Soviet Union (CIS states, Baltic states, Georgia and Ukraine), Mongolia and Finland. Broad gauge of 1,600 mm (5 ft 3 in), commonly known as Irish Gauge, is the dominant track gauge in Ireland and Victoria, Australia.

Broad gauge of 1,668 mm (5 ft 5+21⁄32 in), commonly known as Iberian gauge, is the dominant track gauge in Spain and Portugal. Broad gauge of 1,676 mm (5 ft 6 in), commonly known as Indian gauge, is the dominant track gauge in India, Pakistan, Bangladesh, Sri Lanka, Argentina, Chile, and on BART (Bay Area Rapid Transit) in the San Francisco Bay Area. This is the widest gauge in common use anywhere in the world. It is possible for trains on both Iberian gauge and Indian gauge to travel on each other's tracks with no modifications in the vast majority of cases.