In transit planning circles, we joke that “the monorail is the transit system of the future. Always has been. Always will be.” In short, the advantages claimed for monorails have often been exaggerated, while the cost advantages of proven, off-the-shelf technology are often more important.
Monorails, used as industrial conveyors, appear to date from 1821. A short passenger monorail spanned a gorge in Philadelphia’s Fairmount Park for the 1876 Centennial Exposition. From the 1890s through the 1930s, several short experimental monorails of various designs were built and operated—but seldom for very long. The Wuppertal (Germany) Schwebebahn of 1901 was the first successful passenger monorail, and still operates. That system’s unique design can probably be attributed to much of the right-of-way being above a narrow river. A more conventional steel elevated structure would have required lengthy (and therefore large) steel bents to span the river, bents several times the width of dual railroad tracks.
Outside Europe, transit and intercity railways were still almost entirely the bailiwick of private companies, which typically were led by conservative executives who’d risen through the ranks. They’d give the nod to incremental money-saving improvements—especially during the Depression—but seldom bet big on radical new technologies like monorails.
After World War II, though, the technologies of rubber-tired propulsion and of precast concrete structural members had both matured and came together in the 1952 straddle-beam monorail developed in Germany by Alweg. The Alweg demonstration system caught the eye of Walt Disney, and symbolized futuristic transportation at Disneyland beginning in 1959. Futuristic transport, of course, is exactly what you want for a World’s Fair, and monorails served the Italia 61 Exhibition in Torino and the 1962 Century 21 World’s Fair in Seattle.
Japan, having lots of catch-up to do both in urban transportation and in being seen as modern, began its own development of monorail technology based on the Alweg system, beginning with a short line at Inuyama (1962-2008), and most visibly with Tokyo’s Haneda Airport line, opened for the 1964 Olympics. Japan today has a half-dozen monorails in serious public transit service.
As government took more of an interest in public transit in the 1960s and 1970s, monorail had many attributes that looked attractive. It was quieter than conventional elevated trains, didn’t block sunlight to streets below, could negotiate steeper grades and tighter curves, offered smooth riding (at least when new), and—according to manufacturers and promoters—was substantially cheaper. And it was the future! At Disneyland, people who wouldn’t be caught dead on an ordinary city bus stood in line to ride the monorail.
Alas, many of monorail’s technical attributes were shared by other transit technologies, included automated guideway transit/peoplemovers or even conventional elevated trains built on modern concrete structures with noise-reducing roadbeds. Monorail had its own technical challenges, including switching, cabin layout, and passenger evacuation in emergencies. But the biggest hurdle was the proprietary nature of the various monorail systems. Transit agencies might willingly choose such a technology for the initial system—but what would they face decades in the future, when it was time to expand or rebuild the guideway network, or time to buy new rolling stock? Would any suppliers still be in business? Would there be two or more suppliers to make bids competitive? One of the expensive lessons of San Francisco BART in the 1970s had been the value of time-tested off-the shelf track hardware, control/signalling, and passenger cars.
Nonetheless, the siren song of the monorail has attracted elected officials (and voters) for decades. People wax rhapsodic about how monorails could run down the middle of freeway medians or soar across waterways—as if somehow the laws of physics are different for monorails than other systems. In the 1980s, an insistent Dallas city councilman forced a lengthy comparison of technologies before the DART network could begin construction; Houston actually voted to build a system before reversing themselves. Seattle voters on several occasions in the late 1990s voted to build a citywide network before officials instead chose conventional steel-wheel-on-steel-rail. Monorail-mania has now become a meme unto itself, with its own catchy patter song from a 1993 Simpsons episode.
Why monorails are eternally on the horizon is really more a question of technology than history. But in short, monorails don’t do anything other technologies can’t do—usually more reliably and more inexpensively.
Sources: Kim Pedersen, founder of the Monorail Society, has a new book Monorails: Trains of the Future—Now Arriving. My library includes two books from the early 1960s, both called Monorails. One is by Derek Harvey, the other by Hermann Botzow Jr. The Japanese periodical Process Architecture produced two volumes regarding people-movers and monorails: No. 9: New Transport Systems in the World (1979), and No. 47: New Transportation Systems Worldwide - Part II (1984).
As with most transport topics, Wikipedia’s coverage of monorails is pretty obsessive. Its worldwide list of monorails has more than 70 entries, but only about 15 can really be considered multistation urban public transport systems. And of course the Monorail Society has a good history section on its website.