Freeway & Arterial Travel Times


Freeway Travel Time Data

BluFAX equipment has been used to collect traveltime data for both freeways and arterial sites at numerous locations throughout the United States, as well as Brisbane, Australia.

I-95 Corridor Validation Study

The most extensive deployment was made for the purpose of validating GPS-based vehicle probe data procured by the I-95 Corridor Coalition from the Inrix Corporation in connection with its six-state Vehicle Probe Project. In all cases, the equipment performed flawlessly and provided reliable traveltime measures. The initial testing for the I-95 Coalition project was on a heavily traveled 15-mile section of the Capital Beltway (I-495) near Washington, DC. Twenty units were deployed in connection with this data-collection activity and were relocated at different sites as the data collection proceeded. Three data sets were developed in connection with these tests:

  1. Bluetooth data was used to represent "ground truth" due to its anticipated accuracy and large sample sizes.
  2. Floating car data, historically used to provide traveltime data, was collected to verify the Bluetooth data.
  3. GPS data acquired from Inrix, purchased on an area-wide basis by the I-95 Corridor Coalition.

 Comparison of BluFAX with GPS Data in California 

Bluetooth Traffic Monitoring (BTM) technology was compared directly against traveltimes obtained from the toll tag system on a section of I-80 in San Francisco, as shown in Figure 1. BluFAX sensors were collocated with toll tag stations, data was collected over a period of two weeks, and traveltime and speeds were compared directly. The experiment tested whether the sampling rate of BTM technology was sufficient to reflect accurate traveltimes and speeds as compared to toll tag-derived data, and to test the percentage of vehicles sampled as compared to toll tags readers. In addition, the sampling rate was sufficient not only to characterize central tendency (mean and median), but also to estimate variance measures (standard deviation and percentile measures).



The figures below show data from a segment of Interstate I-495 between Washington, D.C. and Baltimore, MD between 6:30 a.m. and 12:45 p.m. Each data point represents the traveltime from a matched detection at each end of the segment. The figure below depicts the impact on traveltime as a result of an incident that began around 10 a.m.. This incident was cleared at approximately 10:50 a.m. and traffic returned to normal at around 11:15 a.m.