Metro expansion refers to the process of increasing the reach and capacity of urban metro systems, which are rapid transit systems designed to transport large numbers of passengers efficiently. This often involves adding new lines, extending existing routes, and building additional stations to connect more neighborhoods and reduce travel times. The goal of metro expansion is to improve public transportation accessibility, alleviate traffic congestion, and promote sustainable urban development. By investing in public transit infrastructure, cities aim to encourage the use of mass transit, reduce reliance on cars, and lower greenhouse gas emissions, contributing to a cleaner environment.