BCE Highway 2

Question 1

What is the standard superelevation rate limit recommended by AASHTO for highways in areas with frequent ice or snow?

Accepted Answer

0.06

Answer

AASHTO limits maximum superelevation to 0.06 (6%) in regions prone to ice and snow to prevent vehicles from sliding on slippery pavement.

Question 2

The California Bearing Ratio (CBR) test is used primarily to evaluate which pavement design parameter?

Accepted Answer

Subgrade soil strength

Answer

CBR measures the bearing strength of subgrade soil relative to a standard crushed stone, directly informing pavement layer thickness design.

Question 3

Which traffic flow condition exists when density reaches its maximum value (jam density) and speed approaches zero?

Accepted Answer

Forced flow

Answer

Forced (breakdown) flow occurs when density is at jam density, vehicles are nearly stopped, and the roadway is congested beyond capacity.

Question 4

A highway curve has a radius of 500 ft and a design speed of 60 mph. What is the approximate centrifugal ratio (v²/gR)?

Accepted Answer

0.47

Answer

Converting 60 mph to 88 ft/s, v²/gR = 88²/(32.2×500) = 7744/16100 ≈ 0.48, closest to 0.47.

Question 5

In the AASHTO flexible pavement design method, what does the Structural Number (SN) represent?

Accepted Answer

Weighted structural capacity of all pavement layers

Answer

SN is the sum of each layer's thickness multiplied by its layer coefficient and drainage coefficient, representing the combined structural capacity.

BCE - Bachelor of Civil Engineering Practice Test