Transportation in Phoenix, Arizona is primarily via private cars. Public transport is run under the brand Valley Metro, and consists of buses and a light rail system. Roads Phoenix auto traffic depends on both freeways and surface streets. Freeways fall under the auspices of the Arizona Department of Transportation (ADOT). Phoenix ranks first in the nation in the quality of its urban freeways, and the state as a whole ranks first in the nation in the quality of bridges. While being the fifth most populous city in the nation, Phoenix's freeways do not suffer from the same type of congestion seen in other large cities. In fact, in a recent study, there is not a single stretch of freeway in Phoenix ranked in the 100 worst freeways for either congestion or unreliability. Part of the reason for this is the extensive freeway system in the city, due to most of that system being funded by local, rather than federal funds, through a half-cent general sales tax measure approved by voters in 1985. Another offshoot of this local funding is that Phoenix is the largest city in the United States to have two Interstate Highways but no three-digit interstates. , the metropolitan area of Phoenix contains one of the nation's largest and fastest growing freeway systems, consisting of over . The freeway system is a mix of Interstate, U.S., and state highways which include Interstate 10, Interstate 17, US 60, Loop 101, Loop 202, SR 51, SR 143, and Loop 303. There are still major additions to routes 101, 202 and 303 underway, as well as several other smaller projects around the valley. State Routes 87, 85, and 74 connect Phoenix with other areas of the Valley and Arizona. The street system in Phoenix (and some of its suburbs) is laid out in a grid system, with most roads oriented either north–south or east–west, and the zero point of the grid being the intersection of Central Avenue and Washington Street. The one notable exception to this is the diagonal Grand Avenue, which runs northwest–southeast. The original plan was for the east–west streets to be named after U.S. Presidents, with the north–south streets named after Native Americans; but the north–south streets were quickly changed to numbers, with numbered Avenues running to the west of Central, and numbered Streets to its east. Major arterial streets are spaced apart, divided into smaller blocks approximately