A System for Travel Time Estimation on Urban Freeways

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Virginia Tech

Travel time information is important for Advanced Traveler Information Systems (ATIS) applications. People traveling on urban freeways are interested in knowing how long it will take them to reach their destinations, particularly under congested conditions. Though many advances have been made in the field of traffic engineering and ITS applications, there is a lack of practical travel time estimation procedures for ATIS applications.

Automatic Vehicle Identification (AVI) and Geographic Information System (GPS) technologies can be used to directly estimate travel times, but they are not yet economically viable and not widely deployed in urban areas. Hence, data from loop detectors or other point estimators of traffic flow variables are predominantly used for travel time estimation. Most point detectors can provide this data efficiently. Some attempts have been made in the past to estimate travel times from point estimates of traffic variables, but they are not comprehensive and are valid for only particular cases of freeway conditions. Moreover, most of these methods are statistical and thus limited to the type of situations for which they were developed and are not of much general use.

The purpose of current research is to develop a comprehensive system for travel time estimation on urban freeways for ATIS applications. The system is based on point estimates of traffic variables obtained from detectors. The output required from the detectors is flow and occupancy aggregated for a short time interval of 5 minutes. The system for travel time estimation is based on the traffic flow theory rather than statistical methods. The travel times calculated using this system are compared with the results of FHWA simulation package TSIS 5.0 and the estimation system is found to give reasonable and comparable results when compared with TSIS results.

Travel Time Estimation, Urban Freeways, Incidents, Delays, Bottlenecks