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”1. This rule contains numerous provisions, two of which are addressed in this study. The first provision addressed in this study states 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, due to propagation effects at the measurement locations, the result was that measured sound levels off to the side of the locomotive were often higher than levels in front of the locomotive. The FRA proposed this provision to prevent the excessive distribution of sound to the side, which adds to community noise exposure. This provision could force railroad operators to relocate most center-installed horns. A large number of negative comments were received on this provision, suggesting that this relocation would be unacceptable for the locomotive crew.