i've been there before by cp-248, and where do most railfans prefer to watch/photograph the action at there? its one hell of a hotspot in my opinion!
Danbury - (CP-248) is best as there is no really good spot on the East end of the Bay causeway until you get to Venice (CP-244).
AFAIK, the access by the old cement plant is closed and blocked.
For some really good shots, rent / charter a small boat and go out on the Bay by the causeway and bridge.