The ads read "Man Vs Train", and pit a 170 pound man against a 80 ton LRV ("80 tons of American Steel" is the tag line - ha ha). The ads also have a pseudo warning sign that reads "See Tracks Think Train". The LRV depicted in the ads looks similar to the ones being built for GLX, except it has red stripes instead of green. Although the Operation Lifesaver logo was included on the ads, a Google search seems to indicate that this a privately funded effort that O/L is supporting.
I think this a good idea except for one thing. The MBTA's ad contractor has seen fit to intentionally minimize exposure of the message by placing a bunch of these ads on single cars, instead of placing one or two of these ads on multiple cars. Guess they haven't yet figured out that this group and other companies would prefer one or two of their ads be placed on multiple cars, instead of the
let's be lazy far less efficient practice of placing more of their ads on fewer single cars.