To model a corridor using a CTM, the following information is needed:
- Supply—a network of roads
- Demand—turning ratios and boundary flows
- Control—signal plans
- Parameters—fundamental diagrams
- Scenario information—in the current AMS effort, incidents affecting traffic flow
These elements are outlined in the following table:
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SUPPLY |
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Network of roads represented as links (cells) and nodes. The network is created by selecting links and nodes from a base map, as shown in the following figure. The base map is the I-210 “universe” to be modeled in CTM:
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DEMAND |
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Turning movements (split ratios) at each node. These are the fractions of vehicles that take each available downstream link at each diverge opportunity in the network, as illustrated in the map below. They can be obtained by:
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Boundary flows (demands) at all entrances of the network. They can be obtained by using:
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CONTROL |
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Control elements:
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PARAMETERS |
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Fundamental diagrams for each link. The fundamental diagram illustrates the empirical relationship between flow and density (or occupancy). It conveniently summarizes the effects of:
The diagram can be obtained by measurements from sensors such as loops or procedures in the Highway Capacity Manual. |
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SCENARIO INFORMATION |
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Incidents that affect traffic flow. The current AMS effort focuses on lane blockage events, such as incidents that create bottlenecks. Lane blockages are obtained by cluster analysis, using PeMS loop data and CHP feed. Blockages are characterized by:
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