Access control; Adaptive control systems; Bus transportation; Buses; Information dissemination; Information management; Intelligent systems; Internet of things; Railroad transportation; Railroads; Real time systems; Smart city; Communications systems; Crowd managements; Information and Communication Technologies; Intelligent transportation system; Intelligent transportation systems; Internet of thing; Public transportation systems; Real- time; Sensing technology; Sustainable mobility; COVID-19; Adaptive systems; communication systems; coronavirus disease (COVID-19); crowd management; intelligent transportation system (ITS); Internet of Things (IoT); public transportation (PT) systems; sensing technologies; smart cities