Highlights • A methodology to assess sustainability integration between public transport modes. • The study identified 12 sustainability indicators to measure the level of integration. • Sustainability Integration Index estimated for metro rail and bus in Delhi, India. • Sustainability Integration Index for Moolchand Metro Station was found to be higher. • Bus Frequency increases index higher compared to relocate bus stops and mobility card.

Abstract Major cities in India facing with rapid urbanisation and increase in private vehicle ownership resulting to increased traffic congestion, accidents and emissions. Increasing public transport patronage by shifting commuters from private vehicle would solve these problems to some extent. In this direction, increasing accessibility to public transport may attract choice riders to use public transport and in that case bus services may act as feeder to the main transportation systems such as Metro. Therefore integration of these public transit systems would become a key factor to increase public transit usage and efficiency. In order to improve the integration between these transit systems, it is very important to assess the present level of integration between these systems. Hence the objective of the present study is formulated as to develop a methodology to determine the level of integration (Sustainability Integration Index) between two public transportation modes incorporating sustainability. The approach was finalised to determine a total of 12 identified indicators under three main domains of sustainability (economic, social and environmental) which will measure the existing level of integration between Metro rail and Buses. In this study, data collection was carried out at four Metro Stations and surrounding bus stops in South Delhi, India to calculate the Sustainability Integration Index (SII). The multi-criteria analysis which involved homogenization of the indicators of public transportation was considered. Further suitable weights were obtained to each indicator based on the expert opinion survey conducted and the final SII in the range of 0–100 was estimated for selected metro stations. The developed methodology applied for evaluating three policies referring to integrating Metro and Bus service in Delhi. From the analysis it was found that, the policy of increasing bus frequencies resulted in maximum SII value of 4.8% average increase for all four Metro Stations followed by the policy of relocating bus stops to improve connectivity and the policy of common fare collection with 4.3% and 3.8% increase respectively.