Beltway Shuttle -- A Generic Automated Microbus Application |
In many cases, stations on radial rail transit lines are located at intersections with circumferential freeways ("beltways" or "ring roads"). This allows passengers to be easily dropped off or picked up by automobile. It's sometimes the case that a major trip generator, such as a shopping mall, is located a few kilometers away along the freeway, but is not easily accessible from the station. If an Automated Microbus route could travel along the freeway right of way, it would extend the reach of the rail system to the mall. Because of the short trip length, the on-demand service the Microbus provides would more than compensate for its limited speed. At a 5 second minimum headway, 6 passenger vehicles would be able to carry up to about 3,000 passengers/hr per direction, assuming an average of 5 passengers/vehicle. A short Microbus link running along a freeway could also connect two rail transit lines. This would increase the functionality of the entire rail system. The issue is how to run a two-way Microbus route along an existing freeway right of way without incurring the expense of an elevated structure. Sometimes you can't. But in other cases, there is an answer that can be found in the different design of circumferential freeways in suburban areas, vs. freeways in the CBD. When freeways are built in a CBD, they often have vertical retaining walls along each edge to minimize land use. In suburban areas, however, an earthen slope is commonly used instead. This slope is often wide enough to provide a two-way Microbus right of way without impinging on the freeway shoulder. There are a number of possible freeway designs, but the one considered here is a below-grade or at-grade freeway with arterial overpasses and diamond interchanges. ![]() ![]() |
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