I've mentioned before that you need to include a bridge support at the end of every bridge section. I've shown you an example of long spans with inadequate supports. Well, here's one where the modeler actually did it right. This HO scale bridge has a long section made up of three spans crossing above another track. The modeler was careful to include a bridge trestle (vertical support) for every span end and designed them so as not to block trains passing on the track below them. The modeler has also included a cement foundation under each of the trestle bases as well as appropriate cross bracing between adjacent trestles. On the prototype, a bridge like this could have been built in the 19th century, but in later years would likely be a candidate for a redesign to use a single long span instead of these three short spans to eliminate the complex trestles over the lower track (which in turn would provide increased clearance for larger rolling stock on the lower track).