When is the Horn Used?
Under state and federal regulations, Caltrain engineers are required to sound the train horn as a safety measure to alert pedestrians, vehicles, and workers along the tracks. The horn is sounded in the following situations:
- Grade Crossings: Train horns must be sounded at all public vehicular crossings unless a designated Quiet Zone is in effect. When a pedestrian crossing is directly adjacent to a vehicular crossing, they are considered to be a single crossing.
- Pedestrian Crossings: Train horns must be sounded at pedestrian crossings. There are 11 pedestrian-only crossings along the Caltrain line.
- Emergencies: If there is a vehicle or person in the right-of-way, the engineer will sound the horn.
- Stations: The horn may be used when leaving a grade-separated station if there are people near the tracks.
- Work Zones: When workers are present along the tracks, the horn is used to signal the train's approach so they can clear the area.
Horn Decibel Level
Per Federal Railroad Administration (FRA) regulations, the train horn is required to be between 96 and 110 decibels (dB). This volume ensures that the horn is loud enough to be heard by pedestrians and motorists, even in noisy environments. For the new electric trains, the horns have been reduced to 96-97 dB as of December 2024.
Location of the Horn
The horn is mounted under the cab at the front of the train. This placement directs sound forward down the tracks.
Quiet Zones
A Quiet Zone is a section of a rail line at least one‐half mile in length that contains one or more consecutive public highway‐rail grade crossings at which locomotive horns are not routinely sounded when trains are approaching the crossings.
Quiet Zones can only be created by the public authority responsible for traffic control or law enforcement at crossings. Along the Caltrain corridor, that is most likely the city or county the crossing is located in. Quiet Zones must be approved by the FRA and the requesting entity must also accept liability for the Quiet Zone.