NG & NNG: Shanahan family of railroad contractors?

Students of the Maine Two-Footers will be familiar with the names of Richard and Thomas Shanahan, the infamous contractors who were responsible for the original construction (or non-construction as the case may be) of the Sandy River RR in 1879 before their eventual ouster amid charges of drunkenness, embezzlement, general incompetence, etc.

So, imagine my surprise in researching the history of some New York City-area railroads to read that the contractor responsible for the construction in the 1860s of both the Sag Harbor extension of the LIRR and the South Side RR (itself later merged into the LIRR) was none other than...Thomas Shanahan!

However, these two Thomas Shanahans can't be the same person because the one in New York was reportedly killed in the horrific 1869 LIRR train wreck remembered as "the Willow Tree Disaster". (Imagine all the worst accounts of 19th century train wrecks: snake heads coming through the floors of the wooden coaches, coaches telescoping on each other, fires from overturned stoves, etc.) That his death was widely mourned suggests that he was a successful and respected figure, unlike his namesake in Maine a decade later.

A Google search reveals yet another Shanahan involved in railroad building in the 1800s, one James Shanahan who was a contractor involved in the construction of the Starucca Viaduct on the Erie, as well as masonry projects on predecessor lines of the NYC in upstate NY and some locks on the Erie Canal.

So how many people named Shanahan were there building railroads in the northeast US in the mid-late 1800s? Was it some kind of family business?

Perhaps this is more of a question for genealogists than railfans, but I thought I would throw it out there for discussion.

-Philip Marshall