Maglev and Monorails

Monorail trains

--------------------------

Monorails run on single , precast concrete beams that are usually elevated , but can also be at or

below ground level. The trains may travel on top of the beam or hang underneath it. Electrically

driven horizontally and vertically aligned rubber wheels propel the train and keep it stable on the

beam. Rubber tires running directly on the smooth beams suffer little wear, and maintenance is

low compared to metal-wheeled trains that run on metal rails.

Levitation and Propulsion

=========================

Cable coils wound underneath the guideway generate a traveling magnetic field that moves

down the length of the guideway. Magnetic forces of attraction between this field and

electro-magnets on the vehicle levitate the vehicle and drag it along behind the advancing field.

Thus, the guideway acts as both levitation and the propulsion unit. The speed at which the

guideway field travels can be varied for acceleration or braking.

Maglev vehicles

==================

Maglev (short for "magnetic levitation") is a unique mode of transportation that uses

magnetic fields to levitate a vehicle above a specially constructed guideway. Maglev

vehicles, operating at speeds of about 280 mph (450 km/h), could compete with

short-haul flights between cities by offering comparable journey times. Maximum

speeds of 343 mph (550 km/h) have already been achieved at test tracks in Germany

and Japan. Such high speeds are possible due to the lack of contact between the

guideway and the vehicle when it is in motion, so contact friction , a major impediment

for conventional trains, does not have to be overcome. The main source of resistance to

a maglev vehicle is air resistance, which can be reduced by streamlining. Unlike

conventional trains, maglev vehicles do not carry propulsion units on board, instead, the

propulsion system is fitted in the guideway. The innovative guiding and propulsion system

eliminate the need for wheels, brakes, motors, and devices for collecting , converting , and

transmitting electrical power . Meglev vehicles are therefore lighter, quieter, less prone to

wear than aircraft over the same distance. Despite offering the possibility of rapid, and

energy-efficient transportation, maglev has not yet made the transition from experimental to

commercial technology, because of the high cost of constructing new networks of dedicated

guideways.

However, conventionally-propelled monorail trains , which also run on specially constructed

guideways, are gaining popularity as a mode of urban transit. Quiet, efficient , and relatively

non-polluting, they are seen as a solution to the increasing traffic congestion in many modern

cities.

Maglev vehicles are constructed in two parts. The carriage body in which passengers travel is

mounted on an under-carriage that houses the levitation an guidance magnets. The under-carriage

wraps around the guideway and systems controlling the magnets ensure that the vehicle remains

very close to the guideway, but does not touch it.