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AREMA Part 11.5.1

AREMA Part 11.5.1 recommends environmental requirements for electrical and electronic equipment, including microprocessor-based equipment, utilized in railroad signal systems. It outlines the range of environmental conditions of this equipment for storage and operation.

Testing parameters for AREMA 11.5.1 include temperature (operating and storage), relative humidity (operating and storage), vibration, mechanical shock, EMI, dielectric strength and abrasive environment.

Railroad signal equipment operates in a wide range of environments, ranging from benign to severe. A benign environment is one in which the ambient conditions are closely controlled at a predetermined level. A severe environment is one to which no controls or conditioning are applied. These widely differing levels of environmental stress impose very different requirements on signal devices and control equipment. To adequately specify the environmental operating range for each piece of equipment, five classes for wayside and five classes for vehicle are established with parameter levels for each.

Wayside Environment

  • Class A: Roadbed: Equipment is directly attached to track components such as rails, ties, or is mounted between the ties, within striking distance of debris falling from or attached to a train. (Examples: Impedance bonds in electrified territory, wheel detectors, transponders, switch machines, hot bearing detectors, etc.)
  • Class B: Wayside Outdoors: Typical railroad right-of-way. Equipment is located within 20 ft. of the track centerline, but not directly on the track bed. (Examples: Wayside signals, AEI system antennas, junction boxes, etc.)
  • Class C: Wayside Signal Enclosures: Basic shelter from rain and snow is provided, but without heating, air conditioning or humidity control.
  • Class D: Wayside Control Room: Basic shelter from rain and snow is provided. Also, heating is provided, but without air conditioning or humidity control.
  • Class E: Computer Rooms: Ground benign environment, with heating, air conditioning and humidity control.

Vehicle Environment

  • Class F: Vehicle Exterior (Axle Mounted): Equipment is mounted on “unsprung” components of the locomotive, such as wheels and axles.
  • Class G: Vehicle Exterior (Truck Mounted): Equipment is mounted on “sprung” component of the locomotive.
  • Class H: Vehicle Exterior (Platform Mounted): Equipment is mounted in space outside the enclosed areas of the locomotive that are exclusive of direct contact with the rails. (e.g., antennas, AEI tags, etc.)
  • Class I: Vehicle Interior (Platform Mounted): Environment in the enclosed interior spaces of the locomotive, such as the short hoods (designed for crash protection), exclusive of the engine compartment and cab spaces.
  • Class J: Vehicle Interior (Cab): Environment in spaces of the locomotive that are intended for continuous crew occupancy. Includes interiors of transit cars.

Keystone Compliance assists manufacturers with AREMA 11.5.1 compliance. This page lists every method and section of the standard for informational purposes. There may be methods and sections that fall outside of our scope. Please contact us for more information on how Keystone Compliance can assist you with identifying and fulfilling your AREMA 11.5.1 needs.