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. Author manuscript; available in PMC: 2017 Jul 1.
Published in final edited form as: Environ Res. 2016 Mar 31;148:102–111. doi: 10.1016/j.envres.2016.03.036

Table 1.

Road classifications included in our study using 2014 TIGER/Line® files (2010 US Census).

Road
Classification		 Description Study
Classification
S1100 Generally divided, limited-access highways
(interstate highways, including toll highways)		 Primary
S1200 Generally US, State, or County Highway system,
may have multiple lanes, may or may not be
divided, generally include intersections with other
roads/highways (Main arteries)		 Secondary
S1400 Local neighborhood road, rural road, or city street Tertiary
S1500 Vehicular Trail 4WD Tertiary
S1630 Ramp Tertiary
S1640 Service drive usually along a limited access
highway		 Tertiary
S1710 Walkway or pedestrian trail Tertiary
S1730 Alley Tertiary
S1740 Private road for service vehicles Tertiary
S1750 Internal US Census Bureau use Tertiary
S1780 Parking lot road Tertiary