Seismic with transportation loads

I have a large warehouse type building that has a heavy bridge crane in it.  The bridge itself runs along two stationary rails at each end of the bridge.  The crane moves along the length of the bridge. 

I add the load as a transportation load to account for it being in multiple places along the rails and the bridge.  But I have one problem.  On any given day, it will be "parked" at various locations.   In such a situation, it would be considered a dead load that will contribute to seismic.  

QUESTION:  It seems that transportation loads cannot be included in seismic loads as a repeat or reference load.  Can we have this functionality available in future versions?