The toll increase--from 50 cents to $1 on the Turnpike Extension and from $2 to $3 at the Boston Harbor tunnel tolls--was suggested to help the agency pay for its $1.5 billion share of the $14.475 billion Big Dig project, the massive highway reconstruction project going on in the heart of Boston.

The Wall Street firm is concerned about the financial impact the deferred toll increase will have on the agency coupled with the traffic and revenue declines as well as increased security costs due to the recent terror attacks. These concerns are compounded by the recent economic slowdown. In the release, Moody's states that the deferred toll increase will weaken cash flows by about $30 million.