**Published on** May 5th, 2013 |
*by Simi*

# Freeway fastlanes

(a) On a three-lane freeway traffic is flowing at 100km/h. An observer from a bridge overlooking the freeway notices that in each lane exactly 2 seconds elapses between when the back of a car passes her and the front of the next car reaches her. Also suppose that traffic consists entirely of cars that are 5 metres in length. Approximately how many cars pass under the observer in one minute?

(b) Repeat (a) for the case of traffic flowing at 20km/h during heavy traffic. Use the same assumptions about the size and time gap between vehicles.

(c) Repeat (a), (b) for the case where the vehicles are trucks 15m in length.

(d) Now let us take the point of view of a driver. Suppose there are 500 vehicles ahead of you on a lane of the freeway (all being trucks in the case of (c)). Find how long your journey on the freeway takes and the distance covered in each of the above scenarios.

Question created by Chaitanya Rao, Daniel Mathews, Norman Do and Michael Evans

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