Because of the recent urbanization and exponential population growth there has come significant pressure on urban transportation systems. Therefore, people encounter many traffic challenges now a days like traffic congestion, environmental pollution, inefficient public transport, and safety concerns. Smar transportation has been talked about recently in this regard which has emerged as a promising solution for addressing all the mentioned challenges. It integrates advanced technologies such as machine learning, internet of things (IoT) and big data analytics into transportation infrastructure. In this research we aim to explore the role of big data in enhancing smart transportation systems and improving urban mobility. In this research we discuss key challenges that are associated with urban mobility and introduce the concept of smart transportation as solution which is technology driven and automated. We also examine later in this research the characteristics and applications of big data in transportation optimization, including traffic congestion management, public transport route optimization, accident prevention, environmental sustainability, ride-sharing services, and multimodal transportation systems. We also discuss in detail a case study of data-driven ride-sharing platforms such as Uber to show how real-time data analytics can improve mobility efficiency and service reliability.