As we travel around town we pass many things that are just part of the landscape, most times we don’t give it a thought. Other than realizing that if you were driving a truck that was more than 9′ 6″ you might have a problem
This is a railroad bridge in downtown Dover NH, it was built in 1901, in an era before cars and trucks. It is still in use by Amtrak on it’s Boston to Portland passenger train and Pan Am freight trains, and it is described as being in fair condition.
What I find curious is it design for looking down at it it is parallelogram construction and I always wonder why?
antilandscaper 
Counteracts shear. Google answers everything.
The link to the Google book doesn’t highlight so I’ll paste it:
http://books.google.com/books?id=NCI5AAAAMAAJ&pg=PA61&lpg=PA61&dq=why+parallelogram+for+steel+bridges?&source=bl&ots=8sJAmSyfsl&sig=sV6M5uTV2NuCg8iFr0isZxgiZcQ&hl=en&sa=X&ei=4pQHU-OFJLPKsQTG1IDIBQ&ved=0CCkQ6AEwAA#v=onepage&q=why%20parallelogram%20for%20steel%20bridges%3F&f=false
Thanks I did look at it and it does make sense, thou I rarely see RR bridges looking that, but who knows maybe their are a lot more of them around, so I will have to keep my eye out for them
Very curious indeed!