Brazilian engineers use to do bridge decks with a prefabricated concrete (this eliminate most of formwork for the deck, and increase the productivity) this peaces are simply supported by the I Girder beams (See the image). It is possible to do sometihng like this with OpenBridge Modeler?
No custom tool yet in OBM to support this. But this is on our enhancement list for a future release.
As a workaround, you could try to use Place Accessories by Path to place cells. It has some drawbacks since you'll have to compute rotation for each line of accessories, and there may be some complications if your bridge has skews.