40.4.1. Design elements

Try these first

1. 1.

   Define design speed in the context of traffic rotaries.

   Hint

   Think about safety in vehicle movement.

2. 2.

   What is the purpose of the exit radius?

   Hint

   Consider how vehicles transition out of the rotary.

3. 3.

   What is the typical design speed for urban rotaries?

   • 20 km/h
   • 30 km/h
   • 40 km/h

   Hint

   Refer to speed limits generally associated with busy areas.

4. 4.

   True or False: The exit radius should be equal to or less than the entry radius in a rotary design.

   • True
   • False

   Hint

   Think about vehicle transition speeds.

5. 5.

   A rotary has an entry radius of 10m. If the exit radius is 1.5 times this entry radius, what should the exit radius be?

   Hint

   Multiply the entry radius by 1.5.

6. 6.

   Discuss the implications of having a very small weaving length at a rotary. How might it affect traffic safety and flow?

   Hint

   Consider what happens when vehicles are too close together.