Speeds
The difference between these two methods of averaging speeds can be illustrated by the following example: Consider two vehicles traveling on a circular loop with length L=1km. The first vehicle is traveling with a speed of 40km/hr while the second vehicle with a speed of 60km/hr. The average speed of the traffic on the loop is obviously 50km/hr. A standing observer over the period of an hour will observe 40 times vehicle 1 and 60 times vehicle 2, concluding that the average speed is 52km/hr. So the local speed observations are biased towards faster moving vehicles since such vehicles will be observed more frequently.
It can be shown that the two average speeds are related to each other according to the following equation:
Equation 9
