33.2.1. Relationship between Speed and Density

Try these first

1. 1.

   Define free flow speed in your own words.

   Hint

   Think about the condition of traffic where vehicles can move freely.

2. 2.

   What is jam density?

   Hint

   Consider the maximum amount of cars that can fit without movement.

3. 3.

   What does Greenshield's model describe?

   • The relationship between speed and flow
   • The relationship between speed and density
   • The relationship between flow and density

   Hint

   Think about what Greenshield emphasizes.

4. 4.

   True or False: As density increases, speed increases.

   • True
   • False

   Hint

   Visualize traffic flow with increasing cars.

5. 5.

   For a road with a free flow speed of 80 km/h and jam density of 250 vehicles/km, calculate the maximum possible flow. Then, find the traffic flow when the density is 100 vehicles/km.

   Hint

   Use Greenshield's equations for your calculations.

6. 6.

   Suppose you notice that the speed approaches 60 km/h as the density reduces to 40 vehicles/km on a certain road. Assuming linearity, calculate the free flow speed and jam density.

   Hint

   Use the inverse relationships to backtrack your values.