For most persons, the individual travel time is the most relevant criterion when planning a route from a given origin to a given destination. Road managers and national economists are interested in the total travel time in a certain region over a certain time interval. Of particular interest is the total delay caused by congestion. The methods to estimate these quantities can be applied directly to stationary detector and probe-vehicle data, or to microscopic and macroscopic models. While microscopic models give the travel time directly in terms of the duration of trajectories, macroscopic models require additional evaluations, either integrating the flow at fixed positions (“virtual detectors”), or generating virtual trajectories from the local speed field \(V(x,t)\) . Generally, the macroscopic estimation is more robust.