Civil Engineering PE Transportation and Traffic Engineering 5 — Questions and Answers
Question 1: A freeway weaving section has a weaving volume of 1,200 vph and a non-weaving volume of 3,000 vph. The volume ratio (VR) used in HCM weaving analysis is:
- 0.286 (Correct answer)
- 0.400
- 0.250
- 0.167
Correct answer: 0.286
VR = weaving volume / total volume = 1,200/(1,200+3,000) = 1,200/4,200 ≈ 0.286.
Question 2: A highway curve has a posted advisory speed of 35 mph. A truck with a center of gravity height of 6 ft and track width of 8 ft negotiates the curve. The rollover threshold lateral acceleration is:
- 0.67g (Correct answer)
- 0.75g
- 0.50g
- 0.80g
Correct answer: 0.67g
Rollover threshold = track width/(2 × CG height) = 8/(2×6) = 0.667g ≈ 0.67g.
Question 3: The MUTCD requires that a 'School Speed Limit' sign be used only when the speed limit applies during specific times. Which beacon type is typically used with school speed limit assemblies?
- Flashing yellow LED beacon (Correct answer)
- Red flashing beacon
- Green steady beacon
- White strobe beacon
Correct answer: Flashing yellow LED beacon
MUTCD recommends flashing yellow LED beacons with school speed limit signs to alert drivers when the reduced speed is in effect.
Question 4: The AASHTO flexible pavement design uses the Structural Number (SN). If layer coefficients are a1=0.44, a2=0.14, a3=0.11, drainage coefficients m2=m3=1.0, and layer thicknesses D1=4 in, D2=6 in, D3=8 in, the SN is:
- 3.48 (Correct answer)
- 4.12
- 2.96
- 5.20
Correct answer: 3.48
SN = a1D1 + a2D2m2 + a3D3m3 = 0.44×4 + 0.14×6×1.0 + 0.11×8×1.0 = 1.76 + 0.84 + 0.88 = 3.48.
Question 5: Speed studies on a road yield the following 85th percentile speed: 52 mph. The posted limit is 45 mph. Based on the 85th percentile rule, the engineer would recommend:
- Raising the speed limit to 50 mph (Correct answer)
- Keeping the limit at 45 mph
- Lowering the limit to 40 mph
- Conducting a volume study
Correct answer: Raising the speed limit to 50 mph
The 85th percentile rule suggests setting the speed limit near the 85th percentile speed; 52 mph rounds to 50 mph per standard practice.
Question 6: A pedestrian crossing has a walk phase of 7 s and a pedestrian clearance interval of 20 s. The crossing width is 60 ft. The minimum pedestrian clearance time required by MUTCD for a walking speed of 3.5 ft/s is:
- 17.1 s (Correct answer)
- 14.3 s
- 20.0 s
- 12.5 s
Correct answer: 17.1 s
Minimum clearance time = crossing width / walking speed = 60/3.5 = 17.1 s, which must be provided as pedestrian clearance interval.
Question 7: In the four-step travel demand model, the step that converts trip productions and attractions into origin-destination trip interchanges between zones is called:
- Trip distribution (Correct answer)
- Trip generation
- Mode choice
- Traffic assignment
Correct answer: Trip distribution
Trip distribution (Step 2) pairs the productions and attractions from different zones into origin-destination trip tables using models like the gravity model.
Civil Engineering PE Transportation and Traffic Engineering 5
A freeway weaving section has a weaving volume of 1,200 vph and a non-weaving volume of 3,000 vph.
The volume ratio (VR) used in HCM weaving analysis is: