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 4
For the West Basin school frontage improvement, a project engineer preparing an operations handoff review uses the traffic stream relation with speed 65 mph and density 39 veh/mi. What flow rate is indicated?
- A2535 veh/hr
- B1624 veh/hr
- C1852 veh/hr
- D2823 veh/hr
Show the answer and worked solution
Answer: A — 2535 veh/hr
Worked solution
- Step 1. Use traffic flow relation
q = k v
q = 39(65) = 2535 veh/hr
Why the other choices are wrong
- Choice B
- A result of 2991 veh/hr runs about 18 percent above the direct product of the given density and speed, and it does not trace back to one clean arithmetic or unit-conversion mistake starting from k = 39 veh/mi and v = 65 mph; multiplying density by speed with no scaling factor gives the correct 2535 veh/hr.
- Choice C
- The listed 1977 veh/hr sits about 22 percent below the direct product of density and speed, and no single unit slip or formula substitution reproduces that exact figure from k = 39 veh/mi and v = 65 mph; apply q = k * v directly, with no downward scaling, to obtain the correct 2535 veh/hr.
- Choice D
- An answer of 3676 veh/hr is about 45 percent higher than the direct product of density and speed, and it cannot be pinned to any single identifiable error worked from k = 39 veh/mi and v = 65 mph; the flow relation q = k * v, computed once with no adjustment, produces the correct 2535 veh/hr.