Document 13504052

```Introduction to Transportation
Systems
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PART I:
CONTEXT,
CONCEPTS AND
CHARACTERIZATION
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Chapter 5:
Networks
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Representation
NODES
Figure 5.1
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Networks
 Transportation
networks are
interconnected.
 We have connections between the
network elements that are called
nodes, which often represent
terminals or stations.
 In most transportation cases, the
network is redundant. There are
usually multiple ways to travel
between nodes.
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are typically guideways,
highways, rail lines, air corridors,
etc.
 We have links that can take flows,
typically of vehicles, in one or both
directions.
 Links often have a capacity (e.g.,
vehicles/hour).
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Capacity
Capacity defined as a link volume
beyond which the travel time is infinite.
Travel Time/Capacity Volume
∞
Travel time
Capacity
Figure 5.2
Volume
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Another Idea
Volume
(vehicles/hour)
Figure 5.3
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Hierarchical Networks
 Highways
 Local
Streets
 Collector Streets
 Arterial Streets
 Expressway
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Intermodal Network
Air Corridors
Transit
Station
Airport
Park and
Ride
Air Corridors
Figure 5.4
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Nodes
Nodes often represent
A
operation
 An airport
 A parking lot
Nodes have a capacity limit also.
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3 Lanes
2 Lanes
PHYSICAL FACILITY
intermediate
node
2-lane section
Figure 5.5
3-lane section
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Mathematical Operations
on Networks
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9
5
8
6
4
2
3
1
Figure 5.6
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Origin-Destination Matrix
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2
3
4
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6
7
8
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Figure 5.7
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2
3
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0
f12
f13
f14
5
6
7
8
9
0
0
0
0
0
0
0
0
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Traffic Assignment
 Assign
traffic to shortest path
between origin and destination
 All or nothing assignment
 Incremental assignment
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Other Ideas
The inverse problem: estimating