USA Banner

Official US Government Icon

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure Site Icon

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Feasibility of a Train Horn with Optimized Directivity: Environmental and Occupational Noise Benefit of an Ideal Train Horn

Document Series
Technical Reports
Federal Railroad Administration
Report Number
Subject Grade Crossing Technology, Highway-Rail Grade Crossings
Horn, noise, highway-rail grade crossing, safety, environment, occupational, detectability, acoustic hailing device, rolling stock, train horn

This report examines the feasibility of and recommends an acoustical specification for such an optimized horn. The detectability of the horn signal for motorists inside vehicles, the areas of environmental noise impact and occupational noise exposure have been compared for the optimized horn and several typical standard horn systems. It has been found that detectability could be improved and noise impact area reduced by 50 percent or more, depending on amplitude. The optimized horn must have a variable directivity pattern that dynamically changes as a function of train position relative to the crossing to provide substantial noise reduction. Current acoustic source technologies which generate directional sound are examined including “acoustic hailing devices”—a recent technological advancement typically used for military applications, naval communication, and crowd control. Capable of focusing high amplitudes of sound within a narrow beam, acoustic hailing devices have been identified as a feasible means of meeting the required specifications. Finally, the study provides general information concerning cost and implementation of the device.

Last updated: Monday, August 29, 2022