Otto, that is not the right causeway. What you have sent is a map of the causeway across Mallett's Bay between Burlington and South Hero, VT. This is now a rail trail and can be accessed from Burlington, but not from South Hero because of a torn up drawbridge.
What I ASSUME the question be originally about is the trestle linking Alburg, VT with Champlain, NY. The Rutland built this line north from Burlington to Alburg in 1904. The line went across Lake Champlain, interchanged with the D&H and CP in Champlain and then went west to Ogdensburg. The trestle was a long wooden structure and the trains were forced to slowly cross the lake. Jay Wulfson, the late original owner of the Vermont Railway, once said he was sorry that he didn't have the foresight to save this link when the VTR took over from the Rutland. The line north of Burlington, across Lake Champlain, to the NYC line near Ogdensburg was torn up in 1964.
Here is a photo link to this line:
http://www.lavigneworld.com/rutland/