Civil Engineering PE Exam Flashcards

The AASHTO flexible pavement design method uses which primary design parameter to characterize pavement structural capacity?

Answer: Structural number (SN) based on equivalent single axle loads (ESALs)

The AASHTO method characterizes flexible pavement capacity using the structural number (SN), which accounts for layer materials and thicknesses, and is designed for the cumulative traffic load expressed as ESALs.

In traffic engineering, the Peak Hour Factor (PHF) is calculated as:

Answer: Peak hour volume divided by four times the peak 15-minute volume

PHF = (Peak Hour Volume) / (4 × Peak 15-Minute Volume), measuring the uniformity of traffic flow within the peak hour; a PHF of 1.0 indicates perfectly uniform flow.

Stopping Sight Distance (SSD) on a highway is composed of which two distance components?

Answer: Perception-reaction distance and braking distance

SSD equals the distance traveled during the driver's perception-reaction time (typically 2.5 s per AASHTO) plus the distance required to brake to a complete stop.

Using the arc definition, what is the degree of curve for a horizontal curve with a radius of 1,500 ft?

Answer: 3.82°

Using the arc definition: D = 5729.58 / R = 5729.58 / 1500 ≈ 3.82°.

According to the Highway Capacity Manual (HCM), Level of Service (LOS) for a basic freeway segment is primarily defined by:

Answer: Density in passenger cars per mile per lane (pc/mi/ln)

The HCM defines LOS for basic freeway segments by density (pc/mi/ln), with LOS A through F corresponding to progressively higher densities and deteriorating operating conditions.

The Marshall mix design method evaluates asphalt concrete using which two primary measured parameters?

Answer: Marshall stability and flow

The Marshall method measures stability (maximum load resistance at 60°C) and flow (deformation at maximum load) to select the optimum asphalt binder content for the mix.

Superelevation runoff on a horizontal curve is defined as the length of roadway required to transition the outside lane cross slope from:

Answer: Flat (0%) to full superelevation

Superelevation runoff is the distance needed to rotate the outside lane from 0% (flat) to the full design superelevation rate; tangent runout is the separate length that removes the adverse normal crown.