Project. VDOT surveillance needs (spun off from FY2000 "Transportation data clearinghouse") Completed
Principal investigator: Hesham Rakha, VTTI, 540-231-1500, rakha@ctr.vt.edu
External contact: James Robinson, VDOT, 1401 E Broad St., Richmond, VA 23219, 804-786-6677
Project Objective: The objectives of this project are to demonstrate the need, compare, evaluate, and implement the provision of real-time travel time information using VDOT's current Advanced Traveler Information Systems.
Project Abstract: Many past analyses and current market forces make it clear that some data sources are absolutely needed. One such data source is current information on roadway travel times. The increased public usage of the World Wide Web (WWW) has resulted in the development of numerous web-based Advanced Traveler Information Systems (ATIS). A key component to these ATIS systems is the provision of real-time travel time information. The introduction of vehicle tags for purposes of toll collection provides a unique opportunity to estimate roadway segment travel times by installing tag readers along major freeway and arterial sections. In addition, real-time travel time information is available from the many inductance loop detectors that are currently installed in urban areas. Furthermore, the use of cellular phones and the development of cellular location systems could be utilized to estimate travel times by tracking vehicles that are equipped with cellular technology.
The objectives of this project are to demonstrate the need, compare, evaluate, and implement the provision of real-time travel time information using VDOT's current Advanced Traveler Information Systems. In addressing these objectives, a number of data sources could be analyzed. The first of these data sources includes the University of Virginia's database of loop detector data from the Hampton Roads Area. This database will serve as a source for analyzing loop detector speed data. The second database source includes the San Antonio tag data that was developed as part of the Metropolitan Model Deployment Initiative (MMDI). Specifically, a total of 50 tag readers were installed along major freeway and arterial sections in San Antonio, and approximately 30,000 tags were distributed to commuters in the San Antonio Area. This study will utilize these data and any other data sources that may be available to conduct the research related to the estimation of roadway segment travel times.
In addressing these objectives, a year's worth of loop detector and AVI data will be analyzed. Algorithms will be developed to match AVI tag reads and to estimate segment travel times using robust smoothing techniques. Typical average yearly, monthly, daily, and time-of-day travel time estimates will be computed using the previously developed travel time algorithms for a selected number of segments. Using these data, statistical tests will be conducted in order to quantify the typical monthly, daily, and time-of-day variability in segment travel times. Finally, based on these statistical analyses, the need for real-time travel time information will be verified.
Other issues related to estimating travel times from single and dual loop detectors will be analyzed and compared to actual travel times. The intent is to collaborate with the University of Virginia in this effort.
Issues relating to the location of AVI tag readers and loop detectors will be analyzed by reviewing the current state-of-the-art and current state-of-the-practice. In analyzing the current state-of-the-practice, the team will contact different system managers, including Transguide (managers of the San Antonio system). Using the current state-of-the-art and current-state-of-the-practice, the team will look into developing methodologies for optimizing the number and location of tag readers. Different optimization techniques will be considered that incorporate the costs associated with readers together with the travel time benefits for a specific combination of readers. The cost of a reader installation will be location specific. For example, installing a reader at a location in which an overhead structure exists will cost less than installing it at a location that does not have an overhead structure. The benefits associated with a specific reader location will be quantified in terms of providing maximum spatial coverage, covering segments with high traffic volumes, and covering segments with high travel time variability. A methodology for characterizing the network behavior and for estimating the number of readers and the location of the readers will be developed and documented.
Coordination with UVA's Smartravel Lab will be effected.
Tasks. The project consists of three tasks. Task 1 involves the development of travel time estimation algorithms from AVI tag data and loop detector data. Task 2 involves developing algorithms for extrapolating missing surveillance data. Finally, Task 3 involves developing algorithms for optimizing the number and location of surveillance technologies in a network.
Milestones: This project is planned to run from July 1, 2000 to Dec. 31, 2002. Task 1 should be completed in the first year, while tasks 2 and 3 should be completed in the second and third years.
Student involvement: Two full-effort GRAs.
Budget. $240,000
Relation to other research. Collaboration with UVA Smartravel Lab projects.
Technology transfer. Publications in professional journals.
Potential benefits. Improve on real-time travel time information technology, thus keeping driver better informed of traffic conditions, weather conditions, etc.
TRB keywords. ITS, data, traveler information.