The Effect of Installation Location on Railroad Horn Sound Levels
Many comments have been received as a result of the Federal Railroad Administration’s (FRA) issuance of a Proposed Rule for the Use of Locomotive Horns at Highway-Rail Grade Crossings. A large group of comments were received on a particular provision within the rule, stating that the sound level generated by the horn, when measured at the side of the locomotive, shall not exceed the sound level measured in front of the locomotive. In the late 1980’s it became the de facto standard to install horns on the top/center portion of the locomotive. This was done in an attempt to reduce the noise exposure for the locomotive cab occupants. However, the result was that measured sound levels off to the side of the locomotive were often higher than levels in front of the locomotive. Consequently, this provision in the FRA’s Proposed Rule may force railroad operators to relocate many installed horns. While supporting comments were made by many municipalities and individuals, negative comments were also received on this provision. In order to document precisely the effect of horn placement on the locomotive, a series of tests were conducted. These tests measured the sound level around the locomotive for five types of locomotive horns, mounted in four locations on two locomotives. By measuring and documenting the variation in sound level around the horn and locomotive in a consistent manner, the differences in sound level output as a function of distance and the differences in noise exposure levels can be assessed.