Travel time and its reliability are key factors in traffic management systems. They are the best indicators of the level of service in a road link and perhaps the most important variables for measuring congestion. A new approach is presented: it estimates highway travel time with the use of the existing toll highway infrastructure. A simple, efficient algorithm was developed to estimate the single-section travel time (i.e., time required to travel between two consecutive ramps on the highway) and the exit time for each ramp (i.e., time required to travel along the exit link plus the time required to pay the fee at the toll gate). With a combination of these two estimations, all required route travel times can be calculated. The proposed algorithm overcomes some limitations of other methods, such as information delay in long routes and excess travel time estimation due to accumulated exit times. The method was applied to the AP-7 highway near Barcelona, Spain, and the results obtained were reasonable and accurate.