Midterm Part B – Pavement Design Pavement Analysis & Design Due: 03/29/2022 6:30 PM (on Canvas)
Part B of the midterm exam consists of designing a pavement structure for traditional NJ
traffic using the AASHTO ’93 and Mechanistic Empirical Design methods. The design life
of the pavement structure is intended to be 15 years. The general pavement structure
consists of an HMA layer (Layer #1) and an Untreated Granular Base (Layer #2), which
is the typical structure used on NJ Routes 55, 295, and 78. Material properties and
pavement layers are shown in the figure below.
A few additional notes:
• Traffic: Traffic information can be found in Appendix A. These reports are directly
from NJDOT and you can assume that these traffic counts are current. For all axle
weights, please use the most conservative estimate. Additionally, for the 30+ axle
weights, you should use 32 kips, 36 kips, and 60 kips for single, tandem, and tridem
axles, respectively. The growth rate of traffic is assumed to be 2%.
• AASHTO ’93: Please use a reliability of 95%, standard deviation of 0.30, and ΔPSI
is 2.0. Base drainage is assumed to be 1.0.
• M-E Design: Fatigue cracking equation can be found here or from the Week 6
Lecture Slides. Please assume a tire pressure of 50 psi, Va = 5.0% and Vbe =
12.0%. Poisson’s ratio for the AC, Base, and Subgrade layers are 0.35, 0.40, and
0.45, respectively. Rutting equation is shown below or in the Week 7 Lecture
Slides. Rutting only needs to be considered in the subgrade layer.
𝑁𝑑 = 1.365𝐸 − 9 ∗ (𝜀𝑐)−4.477
Please determine the layer thickness for the HMA and Base layers. Show all work
for full credit. Provide example calculations for each factor that is calculated. You
can upload a Word Document or PDF to Canvas as your submittal. Good Luck!
APPENDIX A: TRAFFIC INFORMATION FOR NJ
