How the Automated Horn System Works


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A wayside horn is a stationary horn mounted at a railroad crossing, rather than on a locomotive, to deliver a longer, louder, more consistent audible warning to motorists and pedestrians while eliminating noise pollution in neighborhoods for more than 1/2 mile along the rail corridor.

We offer a wayside horn called the Automated Horn System™. The AHS™ sounds like a train horn because the tone modules in the AHS™ horns were digitally recorded from an actual locomotive horn.

Upon receipt of the signal from the track circuit warning system, the AHS™ mimics a train horn for cars on the street nearby until the train reaches the crossing. Once the train has entered the crossing AHS™ stops sounding its horn. This way the AHS™ is able to dramatically reduce the amount of noise pollution generated by locomotive horns.   The AHS™ is also equipped with a Quiet Zone Indicator, a flashing orange "X", that indicates to the train crew that the AHS™ is working properly and that they are not required to sound the locomotive horn.  If the AHS™ is not performing correctly the Quiet Zone Indicator will extinguish and the train engineer will be required to sound the locomotive horn.


Improved Audible Warning for High Speed Rail Lines

AHS™ provides improved audible warning for drivers approaching crossings located on high speed rail lines. The FRA train horn rule requires that locomotives traveling faster than 45mph sound the horn 1/4 mile in advance of the crossing. This results in reduced audible warning time for trains traveling 60 mph or faster.

Horn GraphAn 80-mph train would provide approximately 11.3 seconds of audible warning, if the driver could hear the horn when it was first sounded 1/4 mile away. AHS™, when installed at locations equipped with constant warning circuitry, provides a minimum of 20 seconds of warning regardless of the approaching train speed. Being at the crossing and focused on the roadway, the audible warning is louder than a train horn would be unless the train is very near the crossing.

How AHS™ Connects to the Railroad

AHS™ connects with the railroad’s crossing warning system in a manner similar to traffic signal preemption connections. Typically AHS™ horns and control cabinets are mounted on their own pole assemblies. The Quiet Zone Indicator is attached to the top of one of the pole assemblies and must provide a clear line of sight to approaching trains from 1/4 mile away. Power is typically provided by the city.