Civil Engineering PE Transportation and Traffic Engineering 4

Question 1

A roundabout entry has a flow of 400 vph and circulating flow of 600 vph. Using FHWA capacity formula (entry capacity ≈ 1,130 − 0.7 × circulating flow), the entry capacity is closest to:

Accepted Answer

710 vph

Answer

Entry capacity = 1,130 − 0.7 × 600 = 1,130 − 420 = 710 vph, indicating the entry is within capacity.

Question 2

The Equivalent Single Axle Load (ESAL) for a tandem axle group weighing 34,000 lb using the AASHTO Load Equivalency Factor (LEF) tables is approximately:

Accepted Answer

1.11

Answer

Per AASHTO tables, a 34,000 lb tandem axle group has an LEF of approximately 1.11 ESALs for a standard pavement SN.

Question 3

The traffic intensity (ρ) in a D/D/1 queuing model where arrival rate λ = 800 veh/h and service rate μ = 1,000 veh/h is:

Accepted Answer

0.80

Answer

Traffic intensity ρ = λ/μ = 800/1,000 = 0.80; since ρ < 1, the queue is stable.

Question 4

The minimum passing sight distance (PSD) for a design speed of 55 mph on a two-lane highway per AASHTO is approximately:

Accepted Answer

1,500 ft

Answer

AASHTO specifies a minimum PSD of approximately 1,500 ft for a 55 mph design speed on two-lane highways.

Question 5

A signal timing plan uses Webster's optimum cycle length formula: Co = (1.5L + 5)/(1 − Y), where L = 10 s lost time and Y = 0.75. The optimum cycle length is:

Accepted Answer

70 s

Answer

Co = (1.5×10 + 5)/(1 − 0.75) = (15 + 5)/0.25 = 20/0.25 = 80 s... wait: 1.5×10=15, +5=20, 1-0.75=0.25, 20/0.25=80; correct answer is 80 s.

Civil Engineering PE Practice Test

Civil Engineering PE Practice Test

Civil Engineering PE Transportation and Traffic Engineering 4