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 8
During a rehabilitation memo for the Pine Ridge school frontage corridor improvement project, the design reviewer records 840 vehicles during a 10-min count interval. What equivalent hourly flow rate is obtained?
- A3326.0 veh/hr
- B5570.6 veh/hr
- C5040.0 veh/hr
- D6036.3 veh/hr
Show the answer and worked solution
Answer: C — 5040.0 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 = 840 / (1/6 hr) = 840 x 6 = 5040 veh/hr
Why the other choices are wrong
- Choice A
- Multiplying the 840-vehicle sample by 4.68 instead of 6.0 leaves the expansion short of what a clean 60-minute/10-minute ratio calls for; that reduced multiplier does not correspond to any valid reading of the 10-minute interval, so the hourly rate comes out too low.
- Choice B
- Applying an 8.7 multiplier to the 840-vehicle count rather than the correct 6.0 factor has no basis in the stated 10-minute interval; the result drives the estimate far above the rate a straight 60/10 expansion of the sample would give.
- Choice D
- Scaling the 840-vehicle count by 7.08 rather than 6.0 pushes the result above the rate a direct 60-minute/10-minute expansion yields; no legitimate reading of the 10-minute count produces that larger multiplier, so the total is overstated.