The National Academies

Transit IDEA J-04/IDEA 59 [Completed (IDEA)]

Recoating Electrified Third Rail Cover Boards - Phase 2

  Project Data
Authorization to Begin Work: 9/22/2009 -- estimated
Staff Responsibility: Harvey Berlin
Research Agency: MINI LLC
Principal Investigator: Arnn Vohra
Completion Date: 6/30/2010
Fiscal Year: 2009

This project built on the successfully completed Transit IDEA Project 44, Recoating Electrified Third Rail Cover Boards. The purpose of this project was to test and demonstrate an operational high speed
system to clean and recoat in-place the fiberglass reinforced plastic cover boards on electrified third rails for rail rapid transit systems. The problem was that the ultraviolet action of the sun on the cover board degrades the protective gel coat and delaminates the glass fibers. The weakened cover board can be blown away by high winds or fall on the third rail. Traction power is lost and the rail system shuts down.

Miami Dade Transit (MDT) participated in this project by testing of the high speed recoating system on their facilities. Other rail rapid transit systems, including Metropolitan Atlanta Rapid Transit Authority (MARTA) and the San Francisco Bay Area Rapid Transit District (BART) participated in reviewing the work in this project. Two high speed cleaning methods, a spray bar and a spinning bar, were considered. The purpose was to clean the cover board surface in one pass, before applying the coating. Two high speed coating application methods, power roller and airless sprayer, were considered. The potential performance of a power roller was discussed with the MDT staff, but it was deemed to be too slow and inefficient and could not coat the curved surface at the corner of the cover board. Airless spray technology appeared to have the desirable attributes. An airless sprayer was carried on a service vehicle and moved along the track to test spray a section of cover board.

It was determined that a water-based coating would be desirable because of the issues of cost and cleaning of the application equipment with solvent based coatings. Several alternative recoating materials were considered and three materials were selected. Coating adhesion tests were performed on two water-based coating products in accordance with the American Society for Testing and Materials (ASTM) standard test D 4541, Standard Test Method for Pull-Off Strength of Coatings Using Portable Adhesion Testers, in cooperation with the coating manufacturers. Two surface coating materials were
applied to cover board segments on the MDT track to evaluate their performance and assist MDT in selection for future application.

The final report is available.

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