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.
Longest 3di's. These highways are all longer than 65 miles (and interstates 86 (west), 19, and 97). For comparison, the longest orbital freeway in the world, in the words of the 2001 Guinness Book of World Records, is the M25 motorway (121.5 miles) encircling London: a 3di in function if not in name. The longest full beltway in the U. S. is Interstate 275 encircling Cincinnati. 1  129.61 miles - I-476, Pennsylvania. 2  121.56 miles - I-495, Massachusetts. 3  98.72 miles - I-287, New York / New Jersey.  95.74 miles - I-135, 1  Kansas. ~86 miles - I-540, Arkansas.  83.71 miles - I-275, Ohio / Indiana 1  / Kentucky. 80.81 miles - I-435, Kansas  City.