This is a relocated/reconstructed wrought iron pin-connected Lenticular pony truss fabricated by the Berlin Iron Bridge Co. in 1887. Its design is typical for its year of manufacture, having tapered vertical web posts and bolted endposts (as opposed to straight web posts and pinned endposts in early models). Unique to this bridge (at least when compared to extant examples) is the date of construction being noted on the top of all 4 endposts. Whether this was original or an added feature is unknown, although given its uniqueness and the fact that the styling of the font differs from other BIBCo bridges of this era suggests that this might have been a one-off item or a later addition.
After being closed for many years this bridge was dismantled and moved from its original location on Northwest Road in Westfield, MA to the Blackstone River Bikeway in Auburn, MA, as a seemingly perfect adaptive reuse of a historic bridge. However in this process both the historical integrity of the bridge and its aesthetic values were compromised, which detracts from the historical experience.
The deck of this bridge is concrete covered in asphalt, and is supported by steel stringers. The trusses, while still having an appearance of its originally fish-belly floorbeams, do not carry the load and are just decorative in nature. It seems odd that the decision was made for such a heavy deck to be used and the existing truss system to therefore not be employed. Surely a truss which carried automobile traffic previously could have handled any sort of pedestrian/bike traffic as built, so the decision to utilize a steel stringer represents a missed opportunity to have a fully functioning truss bridge in an ideal environment for it.
Also the roadway is bound on either side by large heavy fencing, which makes even looking at the trusses difficult. Given the effort to dismantle and move this historic truss, it would have seemed logical to really showcase the bridge. Instead, unless you really look closely (as the bridge and fencing are almost the same color), it would be easy to miss the trusses altogether. This seems especially important given that the lenticular truss is one of the most unusual and, some would argue, beautiful of the truss types around.
Overall, while its of course preferable that this bridge did find a new home as a refurbished pedestrian bridge instead of being scrapped, the condition of this bridge from a preservationists viewpoint leaves a lot to be desired.
To offer an explanation for why the truss is not load-bearing (and why the deck construction is so heavy), I recall reading that MassDOT requires bike paths to be accessible to emergency vehicles, which would require the bridges to be capable of supporting more than just pedestrian and bike traffic. This would be particularly true in this case where the stretch of path between this bridge and the Diversion Channel bridge is inaccessible by road. Additionally, I'm fairly sure that this stretch of path was built as part of the MA 146 reconstruction, which might explain the use of highway standards in the construction. To be fair, I have not read any fine print on this, but if true this could explain why the bridge appears to be overkill for a bike path.