A traffic system is disclosed for use with a plurality of mobile machines. The traffic system may have a locating device configured to generate a location signal indicative of a location of each of the plurality of mobile machines, and an onboard controller configured to regulate operation of each of the plurality of mobile machines based on the location signal. The traffic system may also have a communication device, and a worksite controller in communication with the locating device and onboard controller via the communication device. The worksite controller may be configured to calculate a directed graph of the worksite based on the location signal and known routes for each of the plurality of mobile machines. The worksite controller may also be configured to determine a congestion metric based on the directed graph, and to selectively command the onboard controller to implement a responsive operation based on the congestion metric.