EVALUATION OF SQUEAL NOISE FROM THE WMATA TRANSIT CAR DISC BRAKE SYSTEM: A PRELIMINARY INVESTIGATION

The Washington Metropolitan Area Transit Authority (WMATA) rail transit car design adopted the use of disc brakes as the primary friction braking system. Unfortunately, while disc brakes are more efficient than the traditional tread brake designs, they are also prone to generate unpleasant squeal noise. The purpose of this study was to: (1) inspect the WMATA disc brake assembly; (2) assess disc brake squeal noise occurrence on WMATA vehicles and obtain representative A-weighted sound level measurements; (3) identify and evaluate alternative disc brake squeal; and (4) identify future research and development needs relative to disc brake systems appropriate for use on rail transit vehicles. This report states that disc brake squeal is a chronic and pervasive problem on the WMATA rail transit system. It results in a significant increase in operating sound levels during braking (4 dBA) in a large majority of braking operations (92 percent). Although a noise control treatment has been implemented, its effectiveness has not been clearly documented. Conclusions based on the findings of the investigation are presented in this report, and future research and development needs relative to disc brake systems appropriate for use on rail transit vehicles are identified.

• Record URL:
  https://railroads.dot.gov/elibrary/evaluation-squeal-noise-wmata-transit-car-disc-brake-system-preliminary-investigation
• 
• Supplemental Notes:
  • Prepared by ORI, Inc., Silver Spring, MD.
• Corporate Authors:

  Transportation Systems Center

  55 Broadway, Kendall Square
  Cambridge, MA  United States  02142

  Urban Mass Transportation Administration

  400 7th Street, SW
  Washington, DC  United States  20590
• Authors:
  • Ronk, L A
  • Staiano, M A
• Publication Date: 1981-3

Media Info

• Media Type: Digital/other
• Pagination: 50 p.

Subject/Index Terms

• TRT Terms: Acoustic measuring instruments; Acoustic properties; Acoustics; Brake pads; Disc brakes; Dynamic braking; Noise; Noise control; Rapid transit; Rapid transit cars; Rolling friction; Sound level
• Identifier Terms: Washington Metropolitan Area Transit Authority
• Uncontrolled Terms: Noise reduction
• Old TRIS Terms: Acoustic measurement; Brake disks; Rapid transit railways
• Subject Areas: Environment; Operations and Traffic Management; Public Transportation; Railroads;

Filing Info

• Accession Number: 00337961
• Record Type: Publication
• Source Agency: National Technical Information Service
• Report/Paper Numbers: DOT-TSC-UMTA-81-10 Final Rpt., UMTA-MA-06-0049-81-4
• Contract Numbers: DTRS-57-80-P81005
• Files: NTIS, TRIS, USDOT
• Created Date: Aug 15 1981 12:00AM