The resource Mike put up is a great one, you will be able to use it to pick a few of varying truss types along the I-91 Corridor there in Vermont. You will also be able to use James' map to find your under realized examples there at home.

To answer your question directly, the two I mention in this entry - https://bridgewright.wordpress.com/2011/07/17/crossing-childs-living-legacy/ (use the search box there and you'll find more on the Contoocook RR Bridge) both are uncommon truss types and within a few minutes of I-89 here in NH, part of your probable route from Boston to Burlington.