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Estimationwarm-up
How many hours does the average US commuter spend stuck in traffic each year?
How to approach it
Define 'stuck' first, such as time beyond a free-flowing trip, then estimate the delay per commute and multiply by commuting days.
How a strong answer opens
“First I'd define stuck in traffic as the extra time compared with an empty road. Then I'll estimate that delay per commute for a few types of commuters.”
Outline of a strong answer
Try answering out loud for a few minutes before you open this.
- Define the measure: extra minutes compared with an empty road
- Split commuters by setting: big-city drivers, suburban drivers, rural drivers
- Estimate daily delay for each group
- Multiply by about 250 workdays a year, minus remote days
- Take a weighted average across groups
- Sanity-check: does the total match how long a typical bad commute feels?
Where this question usually goes wrong
Counting the whole commute as time stuck in traffic instead of only the extra time compared with an empty road.
Learn the method
Sanity checks and common slips in Module 3, Estimation.
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