From 1954, a Transit Magazine article about it.

It looks as though it will tip easily, and has none of the style of PCC cars.

The elaborate superstructure necessary to balance the Flying Lady makes you wonder what advantage the designer saw in this contraption. While in Ireland many years ago, we visited the meager remains of a ten-mile scheme that once connected Listowel and Ballybunion - essentially an endless series of A-frames supportig a rail along the top, and a runner along each side to keep the cars upright. Everything was "folded over" the top rail - seats along each side, and the engine with dual boilers. Apparently the scheme was cheaper to build than heavy ties and rails, but it never turned a profit. The story goes that the conductor invited "Mrs O'Malley" to ride instead of taking her donkey cart in the rain. She responded "No thanks, I'm in a hurry today." To my immense surprise, the Irish have since reconstructed enough track to give rides, as shown in the Lartigue Monorailway web site.

for futurists, science fiction writers, amateur inventors, and the general public. But no proposed or built system has ever demonstrated technical, economic, or aesthetic advantages over traditional dual rail systems.

They have demonstrated real disadvantages -- switching problems (making the cost of systems connecting many origins with many destination prohibitive), and safety/operations problems -- reaching passengers stranded on an elevated rail due to accident or breakdown.