Transportation and Infrastructure Planning Flashcards

The AASHTO equivalent single axle load (ESAL) is based on a standard single axle load of:

Answer: 18 kips

One ESAL equals one pass of an 18,000-lb single axle with dual tires.

Using the fourth-power law, doubling an axle load increases flexible pavement damage by roughly what factor?

Answer: 16

Damage scales with (load ratio)⁴, and 2⁴ = 16.

What is the present worth of $10,000 received 10 years from now at a 5% annual interest rate?

Answer: $6,139

P = 10,000 / (1.05)¹⁰ = 10,000 / 1.6289 ≈ $6,139.

Using Webster's method with 12 s of total lost time and a critical flow ratio sum Y = 0.60, what is the optimal cycle length?

Answer: 57.5 s

C₀ = (1.5 × 12 + 5)/(1 − 0.60) = 23 / 0.40 = 57.5 s.

What is the numerical range of the Pavement Condition Index (PCI, ASTM D6433)?

Answer: 0 to 100

PCI runs from 0 (failed) to 100 (excellent).

In infrastructure asset management, preventive pavement treatments give the lowest life-cycle cost when applied:

Answer: While the pavement is still in good condition

Low-cost treatments applied early slow deterioration and delay expensive rehabilitation.

How many vehicle-to-vehicle conflict points does a single-lane, four-leg roundabout have, compared with 32 at a conventional four-leg intersection?

Answer: 8

A single-lane roundabout removes crossing conflicts, leaving 8 conflict points (4 merging and 4 diverging).