Original question written by FE Exam AI Prep from the public FE Civil exam specification. Before release, a solver model re-derived the answer twice from the question alone, without its answer key, and a critic model checked the result, and the arithmetic was re-run as an executable calculation. No licensed engineer reviews these questions. It is not an NCEES question and does not come from any NCEES practice exam. FE Exam AI Prep is an independent study tool and is not affiliated with, endorsed by, or sponsored by NCEES.
Traffic Flow Rate from Vehicle Counts: FE Civil practice problem 3
For the Silver Junction box culvert extension, a resident engineer preparing an independent calculation check records 770 vehicles during a 10-min count interval. What equivalent hourly flow rate is obtained?
- A5114.6 veh/hr
- B5816.5 veh/hr
- C4620.0 veh/hr
- D6410.9 veh/hr
Show the answer and worked solution
Answer: C — 4620.0 veh/hr
Worked solution
- Step 1. Convert count interval to hours
10 min = 10/60 hr = 1/6 hr
- Step 2. Compute hourly flow
q = count/time
q = 770 / (1/6 hr) = 770 x 6 = 4620 veh/hr
Why the other choices are wrong
- Choice A
- This total sits roughly twenty-two percent below the value from converting the ten-minute interval to hours and dividing, a gap that does not trace to one clean identifiable arithmetic slip. Convert 10 min to 1/6 hr, then divide the count by that fraction, equivalently multiply by 6, to reach the correct 4620 veh/hr.
- Choice B
- This total runs roughly forty-five percent above the value from converting the ten-minute interval to hours and dividing, far beyond what a single clean arithmetic slip in this interval conversion would produce. Convert 10 min to 1/6 hr, then divide the count by that fraction, equivalently multiply by 6, to reach the correct 4620 veh/hr.
- Choice D
- This total runs about eighteen percent above the value from converting the ten-minute interval to hours and dividing, a gap that does not trace to one clean identifiable arithmetic slip. Convert 10 min to 1/6 hr, then divide the count by that fraction, equivalently multiply by 6, to reach the correct 4620 veh/hr.