Transit vehicle fires have safety implications for passengers and employees as well as liability implications for manufacturers, suppliers, and operators. The majority of electrical/arcing fire events lead to a total burn out/loss of the vehicle or serious smoke incidents. Fuses and circuit breakers are not designed for this specific failure mode and traditional fire detection and suppression methods have not proven effective. The problem is further complicated by varying engine compartment configurations, equipment layout within compartments, routing of cables, and continuous changes to vehicles to improve environmental impact, weight, and cost. Although there are some technologies and practices that may prove beneficial or perhaps even significantly reduce the frequency and severity of arcing events, original equipment manufacturers and operators are reluctant to implement such technologies and practices due partially to past difficulties and costs. Some preliminary work has been undertaken to determine methods to produce repeatable failure modes for testing of technologies, and efforts related to fire detection in heavy-duty vehicles are currently under way. While the referenced efforts do not specifically test for arcing conditions, the testing standards could be modified to support arcing conditions. Research is needed to avoid unnecessary interruption of revenue service, passenger injury, and expenditure of operating and capital funds for buses and rail passenger vehicles.
The objective of this research is to develop guidance for assessing and mitigating electrical fires on transit vehicles. Accomplishment of the project objective will require at least the following tasks.
(1.) Review relevant practices, performance data, research findings, and other information related to assessing and mitigating electrical fires on transit vehicles (including arcing conditions and electrical and mechanical fires). This information shall be assembled from available literature and from unpublished experiences of transit bus, streetcar, trolleybus, and rail operators, oversight agencies, trade associations, professional associations, standards development organizations, and others. Information on actual field performance is of particular interest—especially as it relates to forensic investigation of transit bus, streetcar, trolleybus, and rail car electrical and mechanical fires, including arcing conditions. (2.) Based on the Task 1 findings, identify the most frequent and severe types of vehicle fires experienced in the transit industry over the last 5 to 10 years, including causes of ignition, zones of fires, contributing factors, heat sources, and items first ignited. Provide details about the characteristics of the vehicles involved: manufacturer, model year, and engine/drivetrain. Provide historical trend analysis on the causes of transit vehicle fires. Identify types of fires on which the TCRP project guidance can usefully focus. (3.) Identify recommended changes and updates for relevant standards, inspection procedures, maintenance procedures, and other widely used guidance (e.g., checklists in standards documents that are out of date). (4.) Identify additional research products and activities that would be beneficial for potential development in Phase II. (5.) Prepare an interim report on the findings and conclusions of Tasks 1 through 4. The interim report shall also contain a detailed work plan for Phase II. The research plan shall provide a 2-month period for review and approval of the interim report. An interim meeting of the project panel to discuss the report with the research agency will be required. For the interim meeting, provide a PowerPoint presentation suitable, upon revision, for posting on the project website. The research agency shall not begin work on the remaining tasks without TCRP approval.
(6.) Carry out the approved Phase II work plan. (7.) Provide a stand-alone technical memorandum titled “Implementation of Research Findings and Products.” (8.) Final deliverables for the project should include (a) a final report summarizing the work, (b) an updated interim meeting PowerPoint presentation and speaker notes for posting on the project website, and (c) a revised Task 6 implementation technical memorandum as a standalone document.