The 24-hour traffic volume count at any station on a specific day in any month of the year is adjusted to Average Daily Traffic (ADT) as __________, where SF is Seasonal Factor, WF is Weekly Factor and DF is Daily Factor.
- ATraffic Volume Count × SF / (DF × WF)
- BTraffic Volume Count × SF / DFCorrect
- CTraffic Volume Count × DF × SF
- DTraffic Volume Count × DF × WF
Solution
Concept
Traffic volume count adjustment factors and ADT calculation
Formula
ADT = Traffic Volume Count × SF / DF
Step-by-step solution
1. A single 24-hour traffic count is subject to daily and seasonal traffic variations. 2. The Daily Factor (DF) normalizes day-to-day variations within the week (dividing by DF). 3. The Seasonal Factor (SF) accounts for month-to-month seasonal variations across the year (multiplying by SF). 4. Hence, the adjusted Average Daily Traffic is expressed as Traffic Volume Count × SF / DF. Answer: B
Explanation
Short-term traffic volume counts (such as a 24-hour count) fluctuate based on the day of the week and the month of the year. To convert a specific 24-hour count to Average Daily Traffic (ADT), adjustment factors are utilized. When the Daily Factor (DF) represents the ratio of traffic on that day to the weekly average, dividing by DF normalizes daily variation, while multiplying by the Seasonal Factor (SF) adjusts for monthly variations: ADT = Traffic Volume Count × SF / DF.
Why the other options are wrong
A) Incorrect: Weekly factor WF is redundant when daily and seasonal adjustments are already applied. C) Incorrect: Multiplying by DF would amplify single-day deviations if DF is the day's proportion. D) Incorrect: Omits seasonal factor SF.
Shortcut
Normalize daily fluctuation by dividing by DF; adjust season by multiplying by SF.
Common mistake
Multiplying by both factors without distinguishing between expansion multipliers and adjustment ratios.
Correct answer: B) Traffic Volume Count × SF / DF