The Monorail Society

ALWEG - Disney/Bombardier


1971 brought a new type of ALWEG monorail to the world- the Disney Mark IV monorail. As in Disneyland before it with the Mark I in 1959, the Mark II in 1961, and the Mark III in 1969, the Mark IV was designed specifically for Walt Disney World. In the 18 years these 10 Mark IV trains were in service, they traveled millions of miles and carried millions of passengers. These trains were so good, two of the later built Mark IV's were later used for the MGM-Bally's Monorail in Las Vegas, a starter line for what is now the Las Vegas Monorail. The ten Mark IV trains had a reliability of 99.962% in the '78-'79 timeframe.


The Mark IV trains were actively marketed for possible transit use up until the mid-1980s. At that time Disney Imagineers decided it was time to replace the fleet of Mark IV trains with similar-looking, but updated designs. They put out for bid the manufacturing of the new trains. Bombardier Mass Transit Division of Canada won the bid to manufacture 12 new trains at a reported cost of $3.575 million per train. These were to be called the Mark VI. These current trains have been in service since the first trains arrived in 1989.

Image: Monorail Black at Grand Floridian


For compatibility reasons, Bombardier kept the standard Disney beamway size of 26" (660mm) wide by 48" (1.22m) in the middle and 80" (2.03m) at the ends. These precast, prestressed girders are between 90 and 110 feet (27.4m to 33.5m) in length. They have a hollow center core to keep the weights under 50 tons. Some of the girders have some combination of vertical and horizontal curvature). The minimum curve radius is 250 ft (76.2m). Compare the Disney beamway to a typical elevated standard rail (4'8.5" [1.435m] gauge)


From 1981 Disney brochure promoting Mark IV system.

TPDisB2The piers per mile count is 50 with monorail, whereas in standard rail the pier count is 75. Also notice the per-mile amounts of steel and concrete required for both monorail and light rail: 4.6 times the concrete and 2.4 times the steel, not to mention the aesthetics.

Dual beam guideways are on 12' centers. To conform with modern transit standards, Bombardier has added an optional emergency evacuation walkway to the design, although it has not been retrofitted to Disney World.


TPDisB8The Mark trains use a slightly different bogie scheme than the Seattle ALWEG and Hitachi ALWEG monorails. Where the Seattle and Hitachi trains have independent bogies that have load wheels that extend into the cars, the Mark III/V, Mark IV and Mark VI trains have load wheels at the ends of the cars, which are attached to the substructure. Also, instead of two tires per axle on the Seattle and Hitachi trains, there is only one on the Mark III/V, IV and VI trains. These load tires are 445/65R22.5 Michelin XTE2 46.6" diameter , 17.8" wide truck tires, the same ones you can see on a dump truck or cement mixer.

The tires are nitrogen-filled to reduce the possibility of fire. They also have run-flat capability. These tires will last 100,000 miles in normal operation. Maximum rated speed for these tires is 65 mph (105 km/h). The load capacity of these tires are 12,800 pounds (5806 kg) each at maximum inflation. There are 12 load tires per 6 car train and 48 guide tires per 6 car train. These guide tires are 21.5" in diameter. In addition, there are two steering wheel tires under each cab car to help steer the suspension up to 3 degrees in either direction. Steering is accomplished in the intermediate cars by the relative geometry of the two adjacent cars. Thus, all 12 load tires are steerable, and the tires are always tangent to the curve.

The main suspension of the cars above the axles is done with air bags (also called air springs). The air bags are automatically inflated/deflated by a leveling valve, which allows varying load conditions. There are also vertical hydraulic shock absorbers.

Bogie of lead and trailer car Bogie configuration between cars

Propulsion, Braking & Power

The Mark VI trains have eight 100hp, 600-volt DC electric motors. These motors also act as brakes by turning the motors into generators and dissipating the power into resistor banks between each car. This is called regenerative braking. Each of the twelve load tires has an 18-inch mechanical disk brake, but the mechanical system generally accounts for less than 1/4th the braking required in normal operation. The dynamic braking slows the train to about 13 mph.

Top speed of the Mark VI trains is 55 mph, but the standard operating speed at Walt Disney World is 40 mph. The propulsion system is called the "Propulsion and Dynamic Braking (P/DB) System." There are two redundant P/DB systems per train, and either is capable of running the train. Each train consumes 138 KWH (kilowatt hours) per operating hour. This translates into a per-train mile of 10.78 KWH, or 0.13 KWH per passenger mile. Power is applied to the traction motors in steps to keep current consumption within the proper limits. Acceleration is 1 mph/s, deceleration is 0.44 mph/s.

The Bombardier M-VI iteration of the trains use a 750VDC primary power source. The power is inverted into alternating current for the traction motors. AC traction motors, also known as VVVF (Variable-Voltage, Variable-Frequency) motors, are more controllable than DC motors. These are the same types of motors used in the latest Japanese Shinkansen "Bullet" trains.

Maximum operating speed is 53 mph (85 km/h) and nominal cruise speed is 45 mph (75 km/h). Acceleration rate is 2.2 mph/s (1.0 m/s2). Normal braking rate is the same. The minimum horizontal radius has been reduced to 175' (53.3m). Maximum sustained gradient is 6%. This design has been proposed for Las Vegas, Houston, and Seattle. This class of trains have been designed to work without an operator by using a moving block train control system (mbtcs) made by Alcatel Canada SEL Division.


Rolling Stock


Mark VI trains are 203'6" long (62m). Cab cars are 40'5" (12.3m) long and intermediate cars are 28'2" (8.6m). Intercar distance is 2' (.61m). Width is 8'4.5" (2.55m), and interior height is 6'10.75" (2.1m). The bottom skirt extends 3'6.75" (1.09m) from the top of the floor. The car body is made of composite shells, and they sit on top of square and round tubing-based truss assemblies (see diagrams). Each car has 4 doors, two on each side. The trains are fully air conditioned. Each Mark VI car can carry 20 passengers seated and 40 passengers standing. Thus, each train can carry 360 people.

Mark VI train configurations at Walt Disney World.



Low cost pivot switches are typically used in the yard and maintenance area. These typically operate in 50 seconds. High-speed (10 seconds) beam replacement switches are used for branching and merging.


High-speed beam replacement switch