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, Speed and Density: FE Civil practice problem 5
For the Riverview retaining wall replacement, a transportation analyst preparing a construction-phase calculation record uses the traffic stream relation with speed 60 mph and density 18 veh/mi. What flow rate is indicated?
- A1080 veh/hr
- B698 veh/hr
- C1235 veh/hr
- D1323 veh/hr
Show the answer and worked solution
Answer: A — 1080 veh/hr
Worked solution
- Step 1. Use traffic flow relation
q = k v
q = 18(60) = 1080 veh/hr
Why the other choices are wrong
- Choice B
- This total runs about eighteen percent above the value obtained by multiplying density directly by speed, a gap that does not match any single clean arithmetic slip in this two-term product. The correct flow rate comes from q = k * v computed once, with no extra factor, giving 1080 veh/hr.
- Choice C
- This total sits roughly twenty-two percent below the value found by multiplying density directly by speed, and it does not trace back to one clean, identifiable arithmetic slip. The correct method multiplies the two given quantities exactly as q = k * v, which comes out to 1080 veh/hr with no reduction applied.
- Choice D
- This total runs roughly forty-five percent above the value obtained by multiplying density directly by speed, far beyond what a single clean arithmetic slip in this two-term product would produce. The correct flow rate comes from q = k * v computed once, with no added factor, giving 1080 veh/hr.