suspension or pier

There are two common bridges. One that is suspension (above or below the deck) like the one that collapsed in Minneapolis or the pier type of bridge just using girders, bridge beams and cross members.




Here from Winona MN is an example of both next to each other.




I think you see some of the problem. How much span can a span span till it don't?

I'm no engineer but I'll bet some are asking that question today.