Balancing the demand and supply of transportation services, while minimizing the negative impacts of congestion, pollution, accidents, and delays is one of the main challenges of traffic flow. OR can help address this challenge by providing tools and methods for analyzing and forecasting traffic patterns and trends using data from sensors, cameras, GPS, and surveys. OR can also optimize the allocation and utilization of transportation infrastructure, such as roads, bridges, tunnels, and parking spaces. Additionally, it can control and coordinate the operation and synchronization of traffic signals, signs, and devices to reduce conflicts and improve safety and efficiency. Furthermore, OR can plan and implement transportation policies and strategies such as congestion pricing, public transit, carpooling, and bike sharing to influence travel behavior and reduce demand. Lastly, OR can evaluate and compare the performance and impacts of different transportation scenarios and alternatives using criteria such as travel time, cost, emissions, and equity.