Slow progress for India's high-speed rail revolution

India's railways are one of the country's defining features, providing transport and employment for millions of people. But the traditional image of chaotic trains and stations is changing as the country invests billions to modernize its rail network.

(CNN) — From Mumbai's packed commuter trains to overnight express mail trains akin to a city on wheels, and the astonishing Darjeeling & Himalayan "Toy Train," railways are one of India's most recognizable features.

Without them, it's unlikely the country would have developed into the economic superpower we see today.

However, as the country evolves, its railways are under increasing pressure to move with the times, deliver faster journeys and more freight capacity to serve India's expanding industries.