<P> India's infrastructure and transport sector contributes about 5% of its GDP . India has a road network of over 5,472,144 kilometres (3,400,233 mi) as of 31 March 2015, the second - largest road network in the world . At 1.66 km of roads per square kilometre of land (2.68 miles per square mile), the quantitative density of India's road network is higher than that of Japan (0.91) and the United States (0.67), and far higher than that of China (0.46), Brazil (0.18) or Russia (0.08). Qualitatively, India's roads are a mix of modern highways and narrow, unpaved roads, and are being improved . As of 31 March 2015, 61.05% of Indian roads were paved . India has the lowest kilometre - lane road density per 100,000 people among G - 27 countries, leading to traffic congestion . It is upgrading its infrastructure . As of May 2014, India had completed over 22,600 kilometres (14,000 mi) of 4 - or 6 - lane highways, connecting most of its major manufacturing, commercial and cultural centres . India's road infrastructure carries 60% of freight and 87% of passenger traffic . </P> <P> Indian Railways is the fourth - largest rail network in the world, with a track length of 114,500 kilometres (71,100 mi) and 7,172 stations . This government - owned - and - operated railway network carried an average of 23 million passengers a day, and over a billion tonnes of freight in 2013 . India has a coastline of 7,500 kilometres (4,700 mi) with 13 major ports and 60 operational non-major ports, which together handle 95% of the country's external trade by volume and 70% by value (most of the remainder handled by air). Nhava Sheva, Mumbai is the largest public port, while Mundra is the largest private sea port . The airport infrastructure of India includes 125 airports, of which 66 airports are licensed to handle both passengers and cargo . </P> <P> Retail industry contributes between 14% and 20% of India's GDP . The Indian retail market is estimated to be US $600 billion and one of the top - five retail markets in the world by economic value . India has one of the fastest - growing retail markets in the world, and is projected to reach $1.3 trillion by 2020 . </P> <P> India's retail industry mostly consists of local mom - and - pop stores, owner - manned shops and street vendors . Retail supermarkets are expanding, with a market share of 4% in 2008 . In 2012, the government permitted 51% FDI in multi-brand retail and 100% FDI in single - brand retail . However, a lack of back - end warehouse infrastructure and state - level permits and red tape continue to limit growth of organised retail . Compliance with over thirty regulations such as "signboard licences" and "anti-hoarding measures" must be made before a store can open for business . There are taxes for moving goods from state to state, and even within states . According to The Wall Street Journal, the lack of infrastructure and efficient retail networks cause a third of India's agriculture produce to be lost from spoilage . </P>

The largest source of national income in india