Ambient noise includes all sounds present in an environ-. ment. The ambient noise level may be measured at any mo-. ment, but it will vary widely with time, e.g., with the coming. and going of trucks and aircraft. Traffic noise is higher at. noon than at midnight and higher still during the morning. and evening rush hours.
(According to the most recent U.S. numbered highway log, published in 1989 by the American Association of State Highway and Transportation Officials, the route is 3,249 miles long). In 1963, therefore, U.S. 20 became the longest road in the country. U.S. 20 is 3,365 miles long according to the 1989 log. The route begins in Boston at a junction with Massachusetts Route 2 and ends in Newport, Oregon, at a junction with U.S. 101.
I-95 is the longest northâsouth Interstate, followed by I-75, and the sixth-longest Interstate Highway overall after I-70 (2,153 miles, 3,465 km), I-10 (2,460 miles, 3,959 km), I-40 (2,555 miles, 4,112 km), I-80 (2,899 miles, 4,665 km), and I-90 (3,099 miles, 4,987 km).