The outlying areas of Houston, the airports and the city's suburbs and enclaves are outside the Loop. Another ring road, Beltway 8 (also known simply as the "Beltway" or as the "Sam Houston Tollway"), encircles the city another 5 miles (8 km) farther out. Parts of Beltway 8 are toll roads, but for most of the route motorists can drive in the adjacent "feeder" or service roads at no charge. Farm to Market Road 1960 (FM 1960) forms a semicircle in northern Houston and is another dividing line. The third ring road, State Highway 99 (also known as the Grand Parkway), is under construction. Long stated that most of the wealthier Houston suburbs are west and north of the central city, while to the southeast the Clear Lake/NASA " another burgeoning concentration of largely aerospace-related prosperity".