New Data Collection Tools Get a Tryout in Denali
Hundreds of thousands of people visit Denali National Park in Alaska
each year. Using new data collection tools, the Federal Highway Administration's
(FHWA) Western Federal Lands office is testing methods to help the
National Park Service (NPS) more accurately count and classify visitor's
vehicles, as well as determine when it is safe to open roads to traffic
in the spring. With this data, the NPS can then make better planning
decisions.
In August of this year, Federal Lands conducted a pilot study in the
park using a Nu-metrics NC-97 device. The counter/classifier measures
the length of a magnetic field to determine a vehicle presence and
its speed and length. "Measuring the length of a vehicle provides
a more accurate way to classify vehicles," says Pete Field of
FHWA. These measurements can help those analyzing the data to better
tell the distribution between automobiles and RVs. Knowing the amount
and type of vehicles helps the NPS to more appropriately size parking
lots and minimize the resulting impact on the parkland.
The small, thin portable device, which is about the size of a Daytimer,
can be bolted to the road. In Denali, the counters were installed
on the road next to the Visitor's Center. "The portability was
definitely an advantage," says Field. "They're good for
studying a fixed location or doing spot studies."
A potential disadvantage is that the devices have a limited collection
time. They can collect 1-week of data at 1-hour intervals and 3-4
days of data at 15-minute intervals. The data then has to be downloaded
and the device recharged.
FHWA is planning a larger pilot program in the park next spring.
The Western Federal Lands staff has also started testing the use of
time-domain reflectometry (TDR) in Denali. TDR has been used by the
communications industry to test underground cables, by the Bureau
of Mines to evaluate mine safety, and by the agricultural sector to
measure soil moisture. The technology is getting a new application
in Denali, however, as FHWA uses it as a ways to measure roadbed strength
in the park and determine whether or not it is safe for vehicles to
travel on them after the winter thaw. The data also helps the NPS
to set weight limits to prevent damage to the road. TDR sensors have
been installed in the ground around Denali to collect data on the
moisture content of the soil. The sensors work by sending a pulse
through three rods and measuring the return time and intensity of
the signal. Signal loss is directly related to soil moisture content.
Data will be collected this spring and winter and then a report will
be issued on the trial use.
For more information on the Nu-metrics counter/classifier device,
contact Pete Field at the Western Federal Lands office, 360-696-7619
(email: peter.field@fhwa.dot.gov).
For more information on the use of TDR in Denali, contact Bob Beck
at the Western Federal Lands office, 360-696-7824 (email: rbeck@wfl.fha.dot.gov).
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| The
Nu-metrics device measures the length of a magnetic field to determine
a vehicle presence and its length. |
Other articles in this issue:
From Arizona to Alaska: Maintaining
access and mobility on federal lands highways
Cold in-place recycling a success
in the badlands
New data collection tools get a tryout in Denali
Combatting pavement roughness with ROSAN
How well do you know your asphalt
mix design?
The ABCs of heat-straightening repair
for steel bridges
Highway technology calendar
