Vehicular ad-hoc networks provide an entirely new way of wirelessly communicating between vehicles in cities. Such communication would eventually lead us to intelligent transportation systems in the transformation process of smart cities. VANET provides vehicular mobility in connectivity through wireless communication between vehicles and between vehicles and roadside units (RSUs) using the IEEE 802.11p standard. This paper summarizes and reviews the operation, applications, services, and conventional traffic management of some research work in VANETs. The techniques include the following: the design of delay-based energy-aware medium access control in VANETs, Virtual Roadside Unit Placement Assisted Communication, and a trust-based secure optimized routing framework for highway VANET communication. These frameworks have been designed using AI, and their performance is found to be superior because they reduce the time spent on travelling, energy waste, and traffic accidents. Further, these frameworks significantly reduce air pollution due to alleviation of traffic congestion beyond conventional methods although at an increased complexity.