The state of Pennsylvania has no legislation that specifically addresses whether train horns are legal to install on cars. The state’s laws about car horns and warning devices suggest that a train horn installed in a car may cause it to fail the mandatory Pennsylvania DMV inspection.
According to the Pennsylvania Code, normal consumer vehicles must have a horn that is clearly audible from at least 200 feet away. However, the code also states that cars may not be
“equipped with a siren, bell, whistle or similar device emitting an unreasonably loud or harsh sound.”
The only exception to this rule mentioned in the code is emergency vehicles. While train horns are not mentioned by name in the list of illegal warning devices, they may be determined to be unreasonably loud because they emit sound at 130-150 decibels. The Pennsylvania Code states that the loudness of the horn must be checked during DMV inspections.
Are Train Horns Legal in Pennsylvania?
Even though installing a train horn as the primary warning device in a car may be illegal, vehicle owners may be able to install them if they do not modify their car’s stock horn and they do not use the train horn. Additionally, the prohibition against loud warning devices includes an exemption for anti-theft devices, so a train horn could be used as part of a car alarm system. Horn modification is not addressed in Pennsylvania’s vehicle code, so it would be best to check with local law enforcement before beginning any installation of a train horn.