12. Traffic Stream Models
Traffic stream models are essential for understanding the relationships between traffic parameters such as speed, density, and flow. The chapter discusses various models like Greenshield's model, which assumes a linear relationship between speed and density, and other advanced models that cater to different traffic conditions. It also addresses the implications of shock waves and presents foundational equations governing traffic flow.
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Sections
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What we have learnt
- Greenshield's model establishes a linear speed-density relationship.
- Other models include Greenberg's logarithmic model and Underwood's exponential model, which address the limitations of Greenshield's assumptions.
- Shock waves in traffic can be understood as points that separate different flow conditions in a stream.
Key Concepts
- -- Greenshield's Model
- A traffic stream model proposing a linear relationship between speed and density, defined by the equation v = v_f(1 - k/k_j).
- -- Shock Waves
- Changes in traffic flow characteristics due to sudden changes in conditions, represented as movements on a flow-density graph.
- -- Macroscopic Flow Models
- Models that treat traffic flow as a continuous medium, focusing on aggregate behaviors rather than individual vehicles.
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