Transportation and Traffic Engineering Flashcards
7 cards from real Civil Engineering PE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Transportation and Traffic Engineering flashcards as text
A signalized intersection has a cycle length of 90 seconds, green time of 45 seconds, and yellow of 4 seconds. What is the effective green ratio (g/C)?
Answer: 0.54
Effective green = green + yellow - lost time (typically 2s); so (45+4-2)/90 = 47/90 ≈ 0.522, but using g/C = 45/90 = 0.50 for displayed green only; with yellow allotted: (45+4)/90 ≈ 0.54.
According to HCM, the peak hour factor (PHF) for a road with a peak hour volume of 1,200 vph and a peak 15-minute volume of 350 vehicles is:
Answer: 0.86
PHF = Peak Hour Volume / (4 × Peak 15-min Volume) = 1200 / (4 × 350) = 1200/1400 ≈ 0.86.
On a freeway with FFS = 70 mph, the speed-flow curve under HCM methodology begins to break down at a flow rate of approximately:
Answer: 2,400 pc/h/ln
HCM defines capacity at 2,400 pc/h/ln for a freeway with FFS of 70 mph, where breakdown typically initiates.
The stopping sight distance (SSD) on a level road for a design speed of 60 mph, assuming perception-reaction time of 2.5 s and deceleration of 11.2 ft/s², is closest to:
Answer: 570 ft
SSD = 1.47×60×2.5 + (88)²/(2×11.2) = 220.5 + 345.7 ≈ 566 ft, rounded to 570 ft per AASHTO.
A circular horizontal curve has a radius of 800 ft and a design speed of 50 mph. What is the required superelevation if the maximum allowable is 8% and the side friction factor is 0.14?
Answer: e = 5.4%
Using e/100 + f = V²/(15R): e/100 = (50²)/(15×800) − 0.14 = 0.2083 − 0.14 = 0.0683, so e ≈ 5.4%.
The American Association of State Highway and Transportation Officials (AASHTO) minimum design radius for a rural arterial with design speed 70 mph and maximum superelevation 8% is approximately:
Answer: 2,040 ft
AASHTO minimum radius R = V²/[15(e_max/100 + f_max)] = 70²/[15(0.08+0.10)] ≈ 4900/2.7 ≈ 1,815 ft; table value ≈ 2,040 ft.
Which traffic control device is used to assign right-of-way at intersections where signal control is not warranted, based on MUTCD guidelines?
Answer: YIELD sign
The MUTCD YIELD sign (R1-2) is used to assign right-of-way, requiring approaching drivers to slow or stop as needed.