# Fundamentals of Transportation/Queueing and Traffic Flow/Additional Problems

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## Additional Questions[edit]

- Why were ideal models of flow vs. density assumed for so long if data did not support it?
- How do we estimate density of road (in planning or as an after-evaluation?)
- Explain why the graph of density vs. speed at a bottleneck is not linear using queueing theory.
- Define time headway and space headway.
- Why do we need two different speed measures, define each, which is more appropriate? How are these measures related?
- What are the 3 fundamental principles of traffic flow? What are their relationships?
- What does the slope on the space time diagram tell you?
- What is the difference between looking at traffic as a particle rather than a flow?
- Define density.
- As density increases, what happens to flow?
- Where are time-space diagrams used?
- What is space headway on a space-time diagram? What is time headway?
- What does high density mean?
- Draw a realistic speed vs. density graph? Compare it with the traditional model.
- Describe headway speed?
- How does a bottleneck affect traffic flow upstream of the point?
- What might cause a falloff of flow as density rises?
- Why does density reach a maximum when flow is zero?
- How do these analysis of mathematical relationships between q,k,v help in planning, design, and operations of road?