Table 3-4 Condition of U.S. Roadways by Functional System: 2000, 2005, and 2011-2013
(Percent of Mileage with an International Roughness Index over 170)
| 2000 | 2005 | 2011 | 2012 | 2013 | Percent Change, 2000 to 2013 | |
|---|---|---|---|---|---|---|
| RURAL | ||||||
| Interstates | 2.1 | 1.7 | 1.8 | 1.8 | 2.4 | 9.9 |
| Other principal arterials | 4.0 | 3.6 | 3.2 | 3.5 | 4.9 | 24.0 |
| Minor arterials | 7.0 | 5.4 | 6.6 | 6.2 | 7.2 | 3.7 |
| Major collectors | 22.1 | 16.1 | 18.6 | 19.1 | 19.7 | -10.7 |
| URBAN | ||||||
| Interstates | 6.5 | 6.0 | 5.2 | 5.0 | 5.1 | -22.3 |
| Other freeways and expressway | 10.9 | 7.8 | 7.8 | 7.4 | 7.2 | -34.3 |
| Other principal arterials | 30.0 | 27.4 | 28.1 | 26.6 | 25.8 | -14.0 |
| Minor arterials | 33.7 | 33.6 | 37.3 | 37.6 | 38.2 | 13.6 |
| Collectors | 52.3 | 49.7 | 53.7 | 52.1 | 53.7 | 2.7 |
NOTES: Numbers may not add to totals due to rounding. Data are reported as the International Roughness Index (IRI) in inches per mile. Lower IRI represents smoother riding roadways. For more information on the rating system, refer to National Cooperative Highway Research Program (NCHRP) report 20-24(37)G, Technical Guidance for Deploying National Level Performance Measurements, available at http://onlinepubs.trb.org/onlinepubs/nchrp/docs/NCHRP20-24(37)G_FR.pdf as of June 2015.
SOURCE: U.S. Department of Transportation (USDOT), Federal Highway Administration, as cited in USDOT, Bureau of Transportation Statistics, National Transportation Statistics, Table 1-27, available at http://www.bts.gov/ as of July 2015.