Current Monorail Technology:-

Current operational monorails are generally of two types - suspended monorail or straddle beam monorail. MonoCab VRT is a straddle beam variant.

Suspended Monorail:-

The suspended monorail (left) has carriages suspended below a steel or concrete track like a pendulum. There are few examples of this type in the world.

Straddle Beam Monorail:-

The typical straddle beam monorail (right) consists generally of a large precast concrete beam between columns. Each beam has to be specially cast to suit it's location - a very expensive exercise.  Their size and weight also creates problems (i.e. costs) with transport to site and erection.

The rolling stock components of these two types are generally of special design which contributes to high costs for design and development and high manufacturing costs due to low production runs.  The cars's load wheels are placed laterally with guide wheels running either side of the concrete beam.

The design of the rolling stock and the tracks limit the minimum turning radius of the track. Typically, the minimum radius is 20 metres which places limits on the track layout.  The maximum grade that the cars can traverse is also limited, generally to 1 in 16 (the MonoCab VRT system has a minimum turning radius of 10 metres and can climb a 1 in 6 grade).

Virtually all of the current operating monorails run multi car "trains" that require a driver.  They run to a schedule and do not operate 24 hours per day like MonoCab VRT.  They are not available on demand.  Their maximum speed seldom reaches 50 km/h and they stop at each station on the route for passengers to embark and disembark.  Consequently, they have quite slow transit times which  discourages patronage.

The current systems are relatively short with a high rate of stations/km.  For example, the Las Vegas monorail has 7 stations on a 4 mile (6.4 km) track.  These stations need to be relatively large as they have to be able to service a monorail that can carry 225 passengers.  They also require staff for successful operation with the resultant cost penalties.

The result is that the whole system is top heavy with expensive stations which explodes the cost per kilometre for the system.  Their high manufacturing, installation and operational costs result in high fares which discourages passengers.

Maglev Monorails:-

The Maglev monorail is a variation of the straddle beam monorail.  It has no wheels.  The train travels elevated slightly above the track (about 8 mm) by magnetic levitation. The most well known example is in China, running between Shanghai city centre and the airport.  It is capable of speeds up to 400 km/h.  The only other commercial operational example is in Linimo in Japan.  This type of monorail is great technology but is handicapped by high construction, operational and maintenance costs.

Further information on monorails is available at:- http://en.wikipedia.org/wiki/Monorail