After happening across these two photos and their captions I tried but I could not find any more information about The Monoroad. Looks like it's circa 1900-1920s to me.
"The monoroad in practical use for carrying passengers at City Island, New York"
"The cigar-shaped car of the monoroad"
"The monoroad in practical use for carrying passengers at City Island, New York"
"The cigar-shaped car of the monoroad"