Wikipedia
GO-Urban was a major mass transit project planned for the Toronto area which would have been run by GO Transit. The system envisioned the use of automated guideway transit vehicles set up in hydro corridors and other unused parcels of land to provide rapid transit services without the expense of constructing tunnels. GO-Urban would serve high-density areas in the downtown core, but also be able to accelerate to high speed between distant stations in the outskirts of the city. Similar deployments were planned for Hamilton and Ottawa.
The planners initially selected the Krauss-Maffei Transurban maglev system as the GO-Urban vehicle, but this ran into serious technical and funding problems and was eventually cancelled in 1974. A new vehicle, known today as the Bombardier ART, was introduced to fill the niche for the Transurban. However, by the time it was ready for service in the early 1980s, changes in the provincial government ended official support for the entire GO-Urban concept. Only a single short demonstration line was built in Toronto, the Scarborough RT.
Although GO-Urban was never built as envisioned, the ART vehicle has seen use in other cities. Today it forms the basis for the majority of the Vancouver SkyTrain system and several shorter lines in cities around the world.