CTE Pavement Design & Materials

Question 1

In AASHTO pavement design, what does the structural number (SN) represent?

Accepted Answer

An index reflecting the structural strength of a pavement to support traffic loads

Answer

The structural number (SN) is an abstract number expressing the overall structural strength of a pavement required to carry projected traffic loads over the design period.

Question 2

What is the primary distress mode that MEPDG (Mechanistic-Empirical Pavement Design Guide) predicts for flexible pavements?

Accepted Answer

Alligator fatigue cracking, longitudinal cracking, and rutting simultaneously

Answer

MEPDG predicts multiple flexible pavement distresses simultaneously — alligator fatigue cracking from bottom-up failure, longitudinal surface cracking, rutting in each layer, and IRI.

Question 3

What is the Equivalent Single Axle Load (ESAL) concept used for in pavement design?

Accepted Answer

Converting mixed traffic of different axle weights into equivalent 18-kip single axle loads for design purposes

Answer

ESALs convert the damaging effect of various axle configurations and weights to an equivalent number of standard 18,000-lb single axle loads, enabling comparison and cumulative damage calculation.

Question 4

What does the California Bearing Ratio (CBR) test measure?

Accepted Answer

The resistance of a subgrade or base material to penetration, used to assess pavement support strength

Answer

The CBR test measures the load resistance of a compacted soil or aggregate material by comparing its penetration resistance to that of a standard crushed limestone material.

Question 5

In flexible pavement design, what is 'rutting' and what layer is most often responsible?

Accepted Answer

Permanent surface deformation in wheel paths; most often caused by the asphalt surface or intermediate layer

Answer

Rutting is permanent vertical deformation accumulating in wheel paths, typically caused by inadequate resistance to shear deformation in the hot-mix asphalt surface or binder course under heavy repeated loads.

CTE - Certified Transportation Engineer Practice Test

CTE - Certified Transportation Engineer Practice Test

CTE Pavement Design & Materials