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fa04_lex5 - 1.221J/11.527J/ESD.201J Transportation Systems...

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1.221J/11.527J/ESD.201J Transportation Systems Fall 2004 LECTURE 5 DISPLAYS SPEAKER: Joseph M. Sussman MIT
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The Elevator Example ± Elevators are simple compared to some of the more complex transportation systems, but they can be instructive and illustrative. ± With this simple example we can gain insight into overall system behavior that we can apply to more complex systems. 2
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Elevator System 60 . . . . . . . 1 ELEVATORS A B C Figure 6.1 3
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Key Point 6: Transfers Intermodal and intramodal transfers are key determinants of service quality and cost. Transfers between elements of the transportation system are often inefficient. In the elevator example, a transfer from the walk-mode as one comes into the building, to the elevator-mode, implies some waiting and, hence, some inefficiency. 4
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Key Point 8: Capacity “Capacity” is a complex, multi-dimensional system characteristic affected by: ± infrastructure ± vehicles ± technology ± labor ± institutional factors ± operating policy ± external factors (e.g., “clean air”, safety, regulation) 5
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Key Point 8: Capacity (continued) In the elevator example, ± We could increase the number of elevators. ± We can also change vehicle technology. For example, we could have larger or faster elevators. ± We could have capacity improvements as a result of control technologies and smarter algorithms for dispatching. 6
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Key Point 9: Supply Level-of-service = f (volume); Transportation Supply . As volume approaches capacity, level-of-service deteriorates dramatically -- the “hockey stick” phenomenon. LOS vs. Volume: The Hockey Stick LOS “H OCKEY S TICK CAPACITY VOLUME Figure 6.3 7
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Direct Elevator Service 8 60 59 58 . . . . . . . . . . . . 2 1 0 Figure 7.1
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Another Elevator Configuration 60 50 40 30 20 10 1 2 3 4 5 6 Figure 7.2 9
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What configuration of elevators makes the most sense? What is the basic trade-off here from the viewpoint of the building owner? 10
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Key Point 11: Infrastructure “Shape” The “shape” of transportation infrastructure impacts the fabric of “geo-economic” structures. 11
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Key Point 14: Cost/Level-of-Service Trade-offs Cost/level-of-service trade-offs are a fundamental tension for the transportation provider and for the transportation customer, as well as between them. 12
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Key Point 15: Demand Consolidation Consolidation of like-demands is often used as a cost-minimizing strategy. For example, when an airline runs a hub-and-spoke operation, it is consolidating people from different origins who have common destinations into airplanes to lower costs. 13
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Key Point 16: “Lumpy” Investment Investments in capacity are often lumpy (e.g., infrastructure). SIDINGS Capacity of Single vs. Double Track Rail Line W ESTBOUND E ASTBOUND ( OPERATIONS IN BOTH DIRECTIONS ) SINGLE TRACK DOUBLE TRACK Figure 7.7 14
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Key Point 17: Capacity, Cost and Level-of-Service The linkages between capacity, cost and level-of- service -- the lumpiness of investment juxtaposed with the “hockey stick” level-of-service function as
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This note was uploaded on 12/06/2011 for the course ESD 1.221j taught by Professor Josephsussman during the Fall '04 term at MIT.