Development of Crash Wall Design Loads from Theoretical Train Impact

摘要

Crash walls may be required for the protection of overhead structures, and in some cases the Railway may consider a crash wall as an alternative to an earthen berm for the protection of structures or facilities adjacent to the track. There is, however, a lack of direction available for the design of such walls. AREMA provides minimum dimensions for crash wall protection of a pier supporting a bridge over a railway, but does not specify design loads; AASHTO design loads are only for tractor-trailer collision forces. Considering basic principles of physics and behaviours exhibited by derailed trains, an energy balance approach was used to determine a reasonable impact load for the design of a crash wall. Two possible modes of impact were considered: a glancing blow from a derailed train running in the direction of the track; and a direct impact as a result of cars piling up in an accordion fashion. The results were compared with previously used guidelines. Comments were solicited from Canadian National, Canadian Pacific Railways, and GO Transit, the regional rail transit system operator in the Toronto Area. Their input was incorporated in the final design guideline which is now being provided to consultants submitting to those railways. This paper reviews the development of the design equations for both modes of impact, and the resulting design guidelines. Minimum requirements for crash walls are included.