bridge crash wall loads

huangyhg

bridge crash wall loads
does any one have a reference on how to design a crash wall at a bridge pier.  arema provides the minimums for the geometry of the crash wall, but not design loads.
the mbta provides a little information, but it is incomlete and does not recommend any methods for design.
tia for any help.

i couldn't find any specific loading or method of load application.  the following was copied from texas dot design manual (on the web).  if the paragraph below does not help, i would contact the engineering dept of the specific railroad involved in the project and simply talk to one of the engineers.  they have been helpful (in my experience) and they might even ascent to sending/faxing some example calcs or better yet, a preferred typical crash wall detail.  good luck.
from txdot design manual:
"sufficient horizontal clearance between an interior support for a highway bridge and an under-crossing railroad track must be provided or a crash wall is required to reduce the chance of the highway bridge collapsing after a hit from a shifted load on a train or a train derailment. when the clear distance from the centerline of the track to the face of the columns is less than 25 ft. but greater than or equal to 12 ft., a crash wall extending 6 ft. above the top of the rail is required. when the clear distance from the centerline of the track to the face of the columns is less than 12 ft., a crash wall extending 12 ft. above the top of the rail is required. crash walls must extend 4 ft. below grade at the base of the wall and be at least 2 ft.-6 in. thick. minimum reinforcing steel areas usually govern. see arema chapter 8, section 2 for complete provisions and the commentary for arema chapter 8 for a useful graphical representation of the provisions."
i concur with what rowe has provided and would only supplement that information with a reference to missouri dot's bridge manual (section 3.71) which can be found online.  that section which describes the requirement for piers also describes pier geometrical requirements for crashwalls.  
there are no requirements for the loading, that i am aware of, in that manual.