Abstract

Approximately 270 noise-level recordings were obtained at 39 highway sites and compared with the noise-level predictions obtained by the procedure outlined in NCHRP Report 117. The measured noise levels were computed in terms of the A-weighted L10 value (level exceeded 10 percent of time) and then compared to the predicted noise levels. A significant discrepancy was found between predicted and measured noise levels; generally, the predicted values exceeded the measured values. Average error per location was 4.8 dBA; the maximum error was 13 dBA. A nomograph was devised to correct the predicted value; this nomograph involves observer-to-roadway distances, truck volumes, and automobile speeds. By applying correction factors, the average error was reduced to 1.9 dBA, a 60-percent reduction in error. Based on these findings, the nomograph was approved by the Federal Highway Administration for use in predicting noise levels in Kentucky.

Report Date

11-1974

Report Number

No. 409

Digital Object Identifier

http://dx.doi.org/10.13023/KTC.RR.1974.409

Notes

Accepted for publication by the Transportation Research Board.

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