So the purpose of the bollards is not to keep cars off the trail, but to keep cars from getting under the bridge. Still why not - as the photographer Rootchopper points out - move the bollards to run along side the trail? Answer: It's probably more expensive. So on the off-chance that a terrorist would target the Wilson Bridge, and to save a little bit of money, this is what we get. I suspect that these bollards will cause more harm than they'll ever prevent.