We say it is a good time to expand the Monorail system. With fuel prices going over the top and all.
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Expanding the monorail really isn't feasible. This post on a recent monorail discussion has a great bullet-point summary:
http://www.disboards.com/showpost.php?p=27467855&postcount=20
It's way too expensive (recent Las Vegas monorail project cost over $600 million for 4 1/2 mile expansion.)
There are no redundancies unless you double or triple the cost by building duplicate tracks side-by-side. Without those duplicates, consider what would happen when a monorail breaks down--blocking the entire track--at park closing time with 20,000-30,000 people waiting to get back to their hotels.
Direct routes would not be feasible. At the very least they would have to create separate loops which all converge at the Transportation and Ticket Center (or a much larger replacement.) For example, DTD, OKW, POFQ, POR and SSR may all be on a "Downtown Disney monorail loop." Guests staying at those locations would board the train at their resort and then be transported to the TTC where they would have to switch trains to reach their theme park of choice. Now imagine 100,000 people converging on the TTC at 9am on a busy summer or holiday day. Care to stand in those lines waiting for the switch of trains?
Rider capacity is also an issue. I believe the current monorails hold about 90 people if you include standing room. And it takes a little over 2 minutes to load a train. Even if they could cut it to 90 seconds per train, that's only 45 trips per hour. 45x90 means they can only transport 4050 guests per hour. I don't think people are going to want to wait around for 4 hours to exit Epcot after Illuminations.
Buses may not be "magical" but they are
scalable (with park closing times staggered, you increase capacity at any given location as necessary), buses are
redundant (when a bus breaks down you dispatch a replacement) and buses offer
direct point-to-point service. You really can't say any of the above about monorails. That is, unless you have several billion dollars to spend.