Table 4-52:  Highway Noise Barrier Construction  (Miles),,,,,,,,,,,,,,,
,,,,,,,,,,,,,Total,,
,Unknown,1970-79,1980-89,1990,1991,1992,1993,1994,1995,1996,1997,1998,1970-98,,
Type I barriersa,d6,102,419,44,78,113,62,48,87,34,47,114,"R1,147",,
Type II barriersb,0,70,128,19,18,18,22,16,32,15,31,22,391,,
All other typesc,N,2,28,0,U,U,U,U,6,0,1,1,79,,
    Total length,6,175,575,63,96,131,84,64,125,49,78,137,"1,623",,
,,,,,,,,,,,,,,,
Cost (1998 $ millions),N,134,656,89,144,186,118,112,152,60,111,169,"1,931",,
KEY: N = data do not exist; R = revised.,,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,
a  A Type I barrier is built on a highway project to construct a new highway or to physically alter an existing highway. ,,,,,,,,,,,,,,,
b  A Type II barrier is built to abate noise along an existing highway (often referred to as retrofit abatement) and is not mandatory. ,,,,,,,,,,,,,,,
c  All other types of barriers are nonfederally funded.,,,,,,,,,,,,,,,
d  Have not been assigned a year of construction or a cost.,,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,
NOTES:  Miles have been converted from kilometers. ,,,,,,,,,,,,,,,
"Totals may not match the sum of yearly estimates due to rounding and converting from metric.  24 miles of barriers, while assigned a year of construction, cannot be assigned a cost. Data are produced on a 3-year cycle. ",,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,
"SOURCE:  U.S. Department of Transportation, Federal Highway Administration, Office of Environment and Planning, HighwayTraffic Noise Barrier Construction Trends (Washington, DC: 2000), tables 1 and 3. ",,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,