UTC Project Information
Project Title
Advancing Traffic Flow Theory Using Empirical Microscopic Data
University
NEXTRANS
The Ohio State University
Principal Investigator
Benjamin Coifman;
Associate Professor; joint appointment, Civil, Environmental and
Geodetic Engineering; and Electrical and Computer
Engineering;
The Ohio State University
PI Contact Information
Coifman.1@OSU.edu
Funding Source(s) and
Amounts Provided (by each
agency or organization)
OSU: 40,000
Total Project Cost
NEXTRANS: $50,000
$90,000
Agency ID or Contract
Number
DTRT12-G-UTC05
Start and End Dates
08/01/2015
Brief Description of
Research Project
Most traffic flow theory is based on macroscopic data collected from
conventional vehicle detectors (e.g., 30 sec average speed, flow, and
occupancy). Traffic flow theory has come to a point where these lowresolution data are now limiting our insight into important phenomena
such as bottleneck formation and operation. Recent theoretical work
has provided a new understanding of bottleneck processes using
microscopic vehicle dynamics (e.g., individual vehicle passages and
trajectories). These works indicate that the conventional macroscopic
data are too coarse to observe the critical dynamics of the bottleneck
process. The coarse granularity of conventional data has led to several
misconceptions. For example, based on macroscopic data the
conventional understanding of the capacity drop phenomena finds that
bottleneck throughput seemingly drops below capacity once the
bottleneck becomes active. Yet the recent theoretical microscopic work
finds that this so-called "capacity drop" appears to be due to an
unsustainable transient increase in flow AFTER the bottleneck has
become active, but before the delays are apparent in the macroscopic
data. Then as activation progresses, the throughput finally drops back
down to the true capacity and the conventional macroscopic studies
erroneously take this instant as the onset of bottleneck activation, thus,
also erroneously taking the unsustainable, supersaturated flows prior to
the drop as capacity. Meanwhile, far downstream of the assumed
bottleneck the throughput never exceeds the true capacity, clearly
indicating that the transient surge is above capacity and is not
sustainable. This proposal seeks to use high resolution traffic data
collected from individual vehicle passages from loop detectors and/or
instrumented probe vehicles to empirically support the microscopic
theories and lead to further traffic flow theory developments based on
the new insights from the high resolution data.
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