Real-time traffic information - Roadway sensors and data probes
Managing freeway traffic requires data and lots of it. The
primary source of data used to understand traffic patterns are
vehicle detectors. There are different types of roadway sensors
based on different technologies such as microwave, audio or video
Currently, the Wisconsin Department of
Transportation primarily uses embedded pavement detectors. Embedded pavement detectors are loops of wire embedded in the
pavement of each freeway lane and the on-ramps where metering is
Detector groups are located approximately every half mile.
When a large metal object passes over the loop, a measurable current
is induced and sent to a roadside controller.
Speed and vehicle count data is gathered for each lane of
traffic. A controller near the collection site totals the data and
sends it to a local traffic operations center via fiber optic cable
or leased line service.
This information provides the foundation for real-time monitoring
of freeway congestion status and is used to set ramp
meter timings. Travel times are calculated from this data and
provided to the media and the public.
Questions about the content of this
page: Traffic Operations Center, firstname.lastname@example.org
Last modified: August 1, 2012