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Class-8 Heavy Truck Duty Cycle Project Final Report - Center for ...

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6.1.1 Spatial In<strong>for</strong>mation<br />

Using the spatial location provided by the on-board GPS (i.e., latitude and longitude collected every<br />

0.2 seconds), the ORNL-developed software determined the road on which the truck was traveling<br />

(freeway, arterial, other), if it was traveling inside or outside an urban area, as well as the state in<br />

which the truck was located. For the latter (state and urban/rural areas), a database with the perimeter<br />

(defined by a series of lat-long points) of each one of the 500+ urban areas in the U.S., and each one<br />

of the lower 48 states was created with in<strong>for</strong>mation obtained from the U.S. Census Bureau. This<br />

database was used to determine, at any instance, the names of the urban area and state in which the<br />

truck was located, or just the name of the state if it was traveling in a rural area. This spatial<br />

in<strong>for</strong>mation was added to the database containing the 60 channels collected by the on-board<br />

equipment.<br />

Much more challenging was the determination of the road on which the truck was traveling,<br />

especially since databases with this type of in<strong>for</strong>mation are not readily available. The first approach<br />

was to use the spatial data collected by the trucks, and by using a GIS software package (Microsoft<br />

MapPoint), to visually determine the type of road (freeway, surface street) as well as the name of the<br />

road (if it were a freeway). The approach used was to divide the area traveled by all of the trucks<br />

during the data collection period (about 13 months) into a grid containing one-degree squares. As the<br />

trucks traveled any particular grid, a database with road location (i.e., a series of latitude-longitude<br />

points gathered by the GPS system) and roadway name (obtained visually from the map used by the<br />

GIS system) was created. Once all of the segments of freeway inside that particular grid were<br />

covered, the grid was classified as “complete” and could be utilized to automatically determine (i.e.,<br />

no longer manually, but by using software) if a truck was traveling on freeways or surface streets<br />

when it was located inside that grid. Fig. 55 shows the 350+ one-degree grids in which the traveled<br />

area was divided.<br />

Fig. 55. One-Degree Wide Grids <strong>for</strong> Roadway Identification<br />

64

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