Civil Engineering PE Transportation and Traffic Engineering Questions and Answers

Question 1

According to the fundamental relationship of traffic flow, what is the traffic flow rate when the traffic density reaches its maximum possible value (jam density)?

Accepted Answer

Zero

Answer

Maximum flow (capacity)

Answer

Equal to the free-flow speed

Answer

Equal to the critical density

Question 2

A horizontal curve on a two-lane rural highway has a radius of 1,200 ft and a design speed of 55 mph. According to AASHTO guidelines, which of the following is the primary purpose of applying superelevation to this curve?

Accepted Answer

To counteract the centrifugal force experienced by a vehicle.

Answer

To improve roadway drainage during storm events.

Answer

To increase the required stopping sight distance around the curve.

Answer

To reduce the required length of the approach tangent.

Question 3

An engineer is calculating the required yellow interval for a signalized intersection approach. The design speed is 40 mph, the driver perception-reaction time is 1.0 second, and the comfortable deceleration rate is 10 ft/s². The approach is on a +2% (uphill) grade. Using the standard kinematic equation, what is the minimum required yellow interval?

Accepted Answer

3.8 s

Answer

2.8 s

Answer

4.5 s

Answer

5.1 s

Question 4

According to the Highway Capacity Manual (HCM), which performance measure is primarily used to determine the Level of Service (LOS) for a basic freeway segment?

Accepted Answer

Density (passenger cars per mile per lane)

Answer

Average control delay (seconds per vehicle)

Answer

Volume-to-capacity (v/c) ratio

Answer

Average travel speed (mph)

Question 5

A traffic engineer needs to determine the required stopping sight distance (SSD) for a vehicle traveling at 60 mph on a roadway with a -3% downgrade. Assuming a standard perception-reaction time of 2.5 seconds and a coefficient of friction (f) of 0.30, what is the approximate SSD?

Accepted Answer

615 ft

Answer

485 ft

Answer

525 ft

Answer

425 ft

Question 6

An engineer is performing a flexible pavement design using the 1993 AASHTO Design Guide. Which of the following parameters is the required direct input to characterize the structural support of the subgrade soil?

Accepted Answer

Resilient Modulus (Mr)

Answer

California Bearing Ratio (CBR)

Answer

Plasticity Index (PI)

Answer

Unconfined Compressive Strength (qu)