Keywords: breakaway connection, catenary pole, derailment, impact.

Additional passenger fatalities and injuries can occur during railcar collisions and derailments due to interaction with wayside structures, such as catenary poles that support overhead line equipment (OLE) over rail tracks. The Federal Railroad Administration of the United States Department of Transportation funded Protection Engineering Consultants (PEC) to develop an alternative base connection for steel catenary poles that can disengage under dynamic impact loads from derailed railcars. PEC devised a friction-based connection with multi-directional breakaway capability, that can be used instead of a typical fixed baseplate connection. This breakaway connection acts as “fusible link” between the catenary pole and the foundation. When the fusible link is overloaded with force of an impact from a derailed railcar, the base of the catenary pole is released from the foundation thereby mitigating the consequences to the railcar and to its passengers. The resistance of the connection under impact loads can be tuned by adjusting the clamping load at the slip surfaces, while appropriately chosen friction materials ensure a reliable and predictable behaviour. Following the initial concept development as informed from analytical and detailed numerical simulations, initial testing on a full-scale breakaway connection prototype was performed under static and dynamic impact loads. These initial tests highlighted the importance of the frictional resistance of the materials used at all the contact surfaces. Various friction material combinations were tested with a custom test apparatus to determine material pairs that provide reliable and predictable frictional resistance for the relatively high contact pressures of the breakaway connection. These friction tests clearly indicated that stainless steel (SS) over bronze (BR) provide steady and predictable frictional resistance. Subsequently, the breakaway connection prototype specimen was upgraded with these new friction materials. Thin sheets of SS and BR were attached to the contact interfaces of the specimen that was subsequently tested under a new series of static and dynamic impact tests. The tests demonstrated the improved performance of the connection prototype and its ability to disengage when impacted with loads above a certain threshold, while remaining fully engaged under design-basis operational loads such as gravity and wind. The test results were used to inform detailed numerical models, which were proven to capture the connection response with high accuracy.

download the full-text of this paper (PDF, 7 pages, 844 Kb)

go to the previous paper
go to the next paper
return to the table of contents
return to the volume description