Regional Rapid Transit System (RRTS) provides passenger transit services between urban & sub-urban towns of a greater metropolitan region. These rail systems operate with fewer stops & faster service compared to intra-city urban rail systems, but with more stops compared to national rail networks. Such systems operate beyond the limits of urban areas and connect the city centers with peripheral urban/sub-urban towns, providing improved access to people who travel within a metropolitan region and enable businesses to have accessibility to a wider set of workforces.

India is implementing its first RRTS in the National Capital Region, a region with 46-million population and encompassing the entire National Capital Territory (NCT) of Delhi and several districts surrounding it from the adjoining states.

India's first RRTS is a rail-based, high-speed high-frequency transit system operating with Namo Bharat trains having a design speed of 180 kmph and an average speed of 100 kmph.