It's been a couple of years since I last mentioned the all-plastic bridges being build by Axion Corporation, but they are in the news again for putting up their longest bridge yet. Keep in mind that the US military was the first entity to use these bridges and they drive 70-ton tanks over them, so their strength is really not a concern.
Oh, did I mention that that these bridges are made entirely from recycled plastic? You know, that cheap, shoddy stuff that many environmentalist organizations like to say is "downcycled"? (1, 2, 3, and 4) As long as bridges are made from both recycled and virgin plastics, it can't be called downcycling. Instead, it's making used of waste that would otherwise be landfilled or incinerated.