The Mark IV monorail (Mk4) was a straddle-type monorail train built for the Walt Disney World Monorail System. The design was developed by Disney Imagineer Bob Gurr. Ten trains were built by Martin Marietta in 1969 at the cost of about $650,000 (~$7.7 million in 2025 dollars) USD each and they were used on the monorail system between 1971 and 1989 before being replaced by the Mark VI monorail, although a few lasted until 1991.
As Walt Disney Productions finalized its plans for the Walt Disney World Resort in Florida, it was decided that monorails would be used as a primary means of transportation for the new “Vacation Kingdom." While the monorail system would not be as extensive as Walt Disney's original plans for the Florida site, it would still be the primary mode for transporting guests throughout the resort. Walt Disney envisioned the monorail as the transportation system of the future. To preserve the aesthetics of the resort and to separate the theme park from the outside world, the parking facilities for the Magic Kingdom were built nearly a mile across the 200–acre Seven Seas Lagoon creating one of the world’s largest park and ride operations. This would be the first Disney monorail system for necessary transportation rather than a ride in the park. Disney had nearly 10 years of experience with the Alweg monorails of Disneyland and designed the new monorails inspired by the look of the popular Lear jets. Disney Imagineer Bob Gurr designed the Mark IV trains, which were manufactured by Martin Marietta in Orlando, Florida with 10 trains originally built. When two additional trains were needed in the mid-1980s as attendance increased, Disney turned to Walt Disney Imagineering to build the additional units.
The trains originally had five cars (all Mark VI trains were introduced as 6-car units). With attendance skyrocketing in the mid-70s, Disney increased capacity and by late 1978 some trains were expanded to six cars. Expansion of the trains continued through the mid-1980s.
The Mark IV monorails were reliable workhorses with a 99.985% operational readiness and a low cost of $0.06 per passenger mile (PPM).
Design The Mark IV monorails were the first of the "Learjet" styled monorails used by Disney (long, sleek white trains with mid-level windows). The design was also used for the Mark V (Disneyland), Mark VI (WDW) and inspired the look of other systems such as the Las Vegas Monorail as well as systems in Asia. Each car featured brown interiors (seat material and carpet) with four double sided and two single (at the front and rear) bench seats which stretched the entire width of the car. The cars were accessed by doors which were automatically opened using a pneumatic system (a loud clunk would be heard and the doors would swing open at the press of a control button on the outside of the monorail near the driver door) and manually closed by a Cast Member (who would walk from one end of the train to the other with his hand out, pushing the doors shut as he walked by). Unlike the Mark VI trains in use at Disney World, Mark IV's were shorter, the cabins were somewhat narrower, and had no standing capacity; all passengers had to be seated. The trains were air conditioned and heated, and each window could be cracked open with a latch. The pilot's compartments (cabs) were not heated. Passengers in wheel chairs were boarded in the middle door of the third car. The door included an opposite hinged side that allowed the passenger to remain in their chair while boarding. Passengers in chairs were boarded using a metal ramp (the floor of the train was several inches higher than that of the station) and one bench seat folded up allowing the chair to be anchored securely for travel without inconvenience to the guest.
Train identification Each train was identified by a colored stripe and given a name according to that color. When Lime and Coral joined the fleet in 1984, to help visually distinguish Green from Lime and Pink from Coral, the Lime and Coral stripes had a delta (Δ) painted across doors 2 and 3 in the middle of each car. Monorail Lime deltas were painted a dark blue in homage to the original Walt Disney World monorail cast's costume colors (lime and blue). Coral's band included white deltas.
The complete list of train colors were:
Red Blue Orange Gold Yellow Pink
Green Silver Black Purple Lime Coral
Identifiable by their deltas.
During night operations, as pilots were unable to see the train stripe from a distance, to designate on which beam (line) the train was operating, the beacon lamps on top of the train were used. The beacon lamps were red or amber (a colored funnel cone was manually adjusted up and down in the housing to change the color of the light). The order of the colors advised other drivers on which beam or track the train was operating:
Red front and rear was an Express Line (exterior) train; Amber front and rear was a Resort Line (lagoon) train; Red in the front and amber in the back was an Epcot Line train.
Due to the difficulty in distinguishing between red and amber at a distance, the Mark VI trains added a third color of green.
Train operations Doors on the train were opened by pressing buttons located next to the cab doors at either end of the train. Cast Members would stand next to the train as it entered and the driver would hold up fingers to indicate how many cars in which there were guests. A circle gesture indicated the train was fully loaded. The doors of each car could be opened independently. Buttons noted as 1, 2, 3, (3A on 6-cars), 4, 5 or there was an "A" (that would open all the doors). There was also an All button located on Car 3. In 1984 an "arming" button was added to prevent unintentional opening of the doors. Cast Members had to hold both the button activating the pneumatic system and the button or buttons for the desired cars they wished to open.
When Walt Disney World opened, there were only two lines—the Express Monorail (to/from the Magic Kingdom parking lot) and the Resort Monorail (which operated as local stopping at the Contemporary Resort, the Polynesian Resort, and the Magic Kingdom). Originally the Resort Monorail did not stop at the Transportation and Ticket Center (TTC) as it was intended for resort guests only. When Epcot opened in October 1982, the resort line began stopping at TTC to allow resort guests to board the Epcot Center Monorail. Conversely the Express Monorail (Magic Kingdom/parking lot) would not stop at the resorts except during the very busiest of times when the first car would not be loaded and the train would stop at the north end of the Contemporary to board hotel guests. When Express trains stopped to embark Contemporary guests, clearances were handled by radio dispatch.
When the resort opened in 1971, both beams operated in the same direction (clockwise—the direction the modern day resort line runs) and based visual clearances and off a standard block light system. Entrance to the Contemporary was only allowed upon receipt of radio clearance due to the inability of pilots to see other trains in the station. For safety reasons, this practice was discontinued by 1973. The Express Line began operating counter clockwise and a flashing white strobe light was added to the rear cab (non-operating end) as an indication of train position for approaching trains. A Moving Blocklight System (MBS), also known as the MAPO system (for Mary Poppins, profits from the film provided funding for the project, ), was installed by the mid-1970s.
Having ten trains and two beams originally, it was seldom that all ten trains were in operation on the same day. Typical operations were three or four parking lot line trains and four resort trains (seven to eight total). During busy times there might be four trains operating on both tracks. This allowed for a rotation of units, have trains available in case of a breakdown, or to perform maintenance which took longer than overnight. When Epcot opened, the typical operation was three trains Epcot Center, three resort trains, and three to four parking lot trains. During the slower fall months, the operations might drop to two trains on Epcot Center, two to three resort trains, and three Express (parking) trains. With the introduction of trains 11 and 12 (Lime and Coral), a four-train operation on all beams was possible. If the Magic Kingdom was especially busy a train would be taken from resorts or Epcot to give the parking lot a five-train operation.
Switching (either moving from track to track or to/from Monorail Shop): When moving trains from one beam to another, other trains on both lines were required to hold outside of the block (or section) containing the switch. Trains being moved were emptied of guests and the entire process was controlled via radio between the switch beam operator (who stood under the switch), the train operator, and Monorail Base (the lead at TTC). At that time Monorail Base oversaw the entire system (Monorail Concourse later took over). The entire process was carefully coordinated and executed. To engage the train's motors during a switching operation, the pilot overrode the automatic anti-collision system throughout (MAPO) the entire switch. Speed through the switches was strictly limited to "nudging" (extremely slow) over most of the switches due to the degree of change; except for the Epcot switches where speed was limited to (the Epcot switches are beam replacement style and have less degree of change). Drivers announced by radio when they had reached designated support pylons at various parts in the switching process. Whenever operationally possible, the switching operation was completed with the train moving in forward and the pilot occupying the cab which allowed him/her to see consistent with the forward operation. Occasionally a portion of the switching operation was completed in reverse. Because operating a train presents significant safety concerns, such operations were only conducted when other trains had been removed from the system and the entire process was supervised by additional personnel to ensure the train would not approach an open switch. Reverse operations with guests on board were prohibited except in extreme situations. Rather than operate a train in reverse with guests on board, having the train towed was preferred.
Procedural safety checks of the anti-collision systems were completed twice each day, when the trains were first placed in service and next between 2:00 and 3:00 p.m. Additional safety checks such as visually inspecting the carbon collector shoes were also performed each afternoon.
Each night as service shuts down, the trains were removed from the beams one route at a time. Usually the Magic Kingdom closed first, followed by Epcot and then the resort trains would cease operations around midnight. Typically the Express (parking lot) trains would "switch ends" (the driver would move to Cab 5) and operate the train in a clockwise direction. They would then be lined up with one at the west side of the switch beam (east of the Magic Kingdom, west of the Contemporary); one in the Magic Kingdom station; one at the top of the hill on the west side of the Magic Kingdom (north of the modern Grand Floridian); one at the Polynesian and, on the rare occasion when five trains were operating—one at TTC. The first train would be cleared through the switch, around behind Space Mountain, and into the Monorail Shop. Following trains would advance one by one forward to where the train in front of them previously had been stopped. This process continued until all the trains were berthed in the shop.