Walt Disney World has a fairly impressive road system, complete with several freeways and expressways. A decent Orlando map will help in understanding this; the inset found in a standard US road atlas is usually good enough.
The roads on Disney Property are maintained by the Reedy Creek Improvement District Department of Public Works; RCID is a pseudo-town set up by Walt Disney to streamline operations.
Walt Disney chose the location to be specifically along Interstate 4, a state maintained freeway on the Interstate Highway System. Thus I-4 runs southwest to northeast along the east border of Disney World. Five interchanges directly or indirectly serve Disney World. The town of Celebration lies southeast of I-4.
US 192, another state maintained road, runs east-west along the south border. Celebration is south of 192. Between I-4 and a bit west of World Drive, both sides of 192 are Disney property, and 192 is a freeway in this area. East of I-4, 192 is a major tourist strip, just recently widened to six lanes. West of Disney World, 192 is a less-developed tourist strip, still allowing relatively high speeds. Traffic to and from the north on Florida's Turnpike uses 192 and US 27. Traffic to and from the south on Florida's Turnpike used to use 192 through downtown Kissimmee, but the Osceola Parkway now serves as a high-speed connection.
The first entrance to Disney World was on 192, via World Drive. Old maps mark World Drive as World Entrance Drive. In the late 1990s, World Drive was extended south across 192 to I-4 at exit 62 (old exit 24CD), with connections to Celebration. South of 192, World Drive has several at-grade intersections. But World Drive is a full freeway once you cross 192. The first interchange in Disney World is with the Osceola Parkway; there is also a northbound offramp here to the Disney/MGM Studios parking lot; no access is provided between the Osceola Parkway and this ramp. All other access to/from Disney/MGM Studios uses Buena Vista Drive, the next interchange to the north. Next is Epcot Center Drive; traffic from northbound World Drive cannot access Epcot Center Drive, only the Epcot parking lot. After a U-turn in the median, World Drive hits the Magic Kingdom gate. After that, the road splits. In the middle is the Magic Kingdom parking lot; around the outside is access to various hotels and backstage areas. World Drive continues in name around the east side of this loop.
SR 535, Kissimmee-Vineland Road, runs north-south east of Disney World. It abuts Disney property just north of its interchange with I-4, exit 69 (old exit 27).
Toll 417, the Central Florida Greeneway, begins on I-4 at exit 62 (old exit 24E), just south of 192 and north of World Drive. 417 is maintained by Florida's Turnpike Authority. It runs northeast through Celebration, crossing 192 (indirect access via Celebration), the Osceola Parkway (direct access), and 535 (no access). Just past 535 is a half-interchange to and from the north, where the northbound road turns east towards Orlando International Airport and a half-beltway of the Orlando area. This interchange feeds into World Center Drive, which connects to SR 536.
SR 536 goes from I-4 exit 67 (old exit 26) to 535. East of 535, the road is county maintained as World Center Drive, with access to International Drive before merging into 417. At the west end, 536 becomes Epcot Center Drive; this west end is a bit west of the I-4 interchange.
Epcot Center Drive is a full freeway, maintained by Disney. At the west end is World Drive and access to the Epcot parking lot. The only interchange between I-4 and Epcot is Buena Vista Drive. At the east end, Epcot Center Drive becomes 536, with access to I-4.
The Osceola Parkway's west end is currently at Disney's Animal Kingdom Lodge; an extension may be built in the future. Next is Sherberth Road, a back way to 192. Just east of Sherberth Road, the Osceola Parkway becomes a full freeway; this happens at the interchange with the parking lot for Disney's Animal Kingdom. Full interchanges are provided at Buena Vista Drive and World Drive. At World Drive, the ramp from the Osceola Parkway eastbound to World Drive northbound crosses the westbound Osceola Parkway, so the freeway ends. East of World Drive is an at-grade intersection with Victory Way, which goes south to the Wide World of Sports and north to Buena Vista Drive. Next is a recently constructed interchange with I-4 (exit 65, old exit 26CD); the ramp from I-4 east to the Osceola Parkway east crosses the westbound Osceola Parkway at grade. At I-4, the Osceola Parkway leaves Disney property, and becomes Osceola County Route 522. Several at-grade intersections lie around the interchange with 417; traffic between Disney World and Orlando International Airport uses the Osceola Parkway to 417. A bit east of 417, at Seralago Boulevard, the Osceola Parkway becomes a toll road. An interchange with 535 has toll booths on some of the ramps, and a mainline toll booth lies in the middle of nowehere. The Osceola Parkway continues past the toll booth as a surface arterial, with access to Florida's Turnpike.
Buena Vista Drive is a four-to-six lane surface road. The south end is at Disney's All-Star Resorts, just south of the Osceola Parkway interchange. North of the Osceola Parkway, Buena Vista Drive curves east and crosses World Drive. Past World Drive is the Disney/MGM Studios parking lot, and then Victory Way, which goes south to the Osceola Parkway and Disney's Wide World of Sports. Soon after is the interchange with Epcot Center Drive. Next is Downtown Disney; this part of Buena Vista Drive has numerous traffic lights and is often plagued with traffic. The majority of this traffic turns off at Hotel Plaza Boulevard, a short connector to 535. Buena Vista Drive continues north to end at Orange County Route 535, a northern extension of SR 535.
Many other minor roads exist, serving various hotels, golf courses, and backstage areas. One major one connects the north side of the Magic Kingdom to Reams Road; Reams Road is a major entrance/exit for cast members.
By 2010, toll 429, the Western Expressway, will have been built west of Disney World by Florida's Turnpike Authority. 429 will begin on I-4 at exit 60, southwest of Celebration. 429 will go north, crossing 192 with an interchange. Another interchange will primarily serve Disney World, with the connector road ending at Buena Vista Drive between the Osceola Parkway and World Drive. North of there, 429 will join to the already completed section at Florida's Turnpike.
Signage on the freeways is much like on normal state-maintained freeways; it is big and overhead. Instead of green, the background is purple. EXIT ONLY tabs are red rather than yellow. And arrows are black circles with white arrows inside. On surface roads, smaller versions are used; many have 'Mickey ears' at the top, with a white arrow in one. World Drive at and south of 192 has standard green signs, probably installed by the state.
Road names are only marked on standard street signs, not on directional signs. Thus Epcot Center Drive is not marked at all, and World Drive is only signed north of the Magic Kingdom gate. The green signs at 192, put up by the state, used to say 'World Dr' and 'Osceola Pkwy', but this text has been covered with solid green.
Exit lists for Disney's freeways can be found at http://web.mit.edu/spui/www/freeway/flfree.html ; these are currently a bit out-of-date. The exit lists have pretty accurate depictions of the signs.