Facility Description
The Berkeley Highway Laboratory (BHL) is a test site
covering 2.7 miles of Interstate-80 immediately east of the San
Francisco-Oakland Bay Bridge. The facility includes fourteen surveillance
cameras and sixteen directional dual-inductive-loop-detector stations
dedicated to monitoring traffic for research purposes. Sponsored
by the PATH program, the video sensors and loop detectors are a
unique resource because they provide individual vehicle measurements
that are not currently available anywhere else. An automated loop
data collection system has been in continuous operation in the BHL
since June, 1999. The system collects individual vehicle actuations
from all 164 loops in the BHL area every 1/60th of a second and
archives both the activation data and a large set of derived data,
such as the passing vehicle streams and travel time information.
The loop data collection system is currently generating approximately
100 megabytes of data per day. A suite of loop diagnostic tests
has been developed over the last 2 years which continuously tests
the data stream received from the loops and archives the test results.
The Berkeley Highway Laboratory has developed over
a number of years and is a joint effort of many individual projects.
The facility itself is a testbed covering 2.7 miles of Interstate-80,
immediately east of the San Francisco-Oakland Bay Bridge. Loop data
is collected from sixteen directional dual-inductive-loop-detector
stations (164 individual mainline loops) 24 hours a day, 7 days
a week. Fourteen surveillance cameras provide video coverage of
the testbed and provide the data needed for several video analysis
research projects. The major components of the BHL have been in
operation since 1999 and have generated a vast archive of data unique
in transportation research. The uniqueness of the BHL loop data
derives from the fact that the BHL provides event data on individual
vehicle actuations, accurate to 1/60th of a second. Most other loop
detector systems collect only aggregated data over periods of 20
seconds or longer. Collecting the individual loop actuations allows
the generation of data sets which are not found elsewhere. This
includes vehicle stream data which can be used for headway studies,
gap analysis, and merging studies. The vehicle lengths are also
available allowing classification of the freeway traffic. One of
the original research projects leading to the development of the
BHL developed a method of calculating travel times between successive
loop stations using a vehicle reidentification algorithm. Travel
time data now forms a part of the rich data set available from the
BHL.
A detailed drawing of the Berkeley Highway Laboratory
is available (pdf)
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