Welcome page Design Guide General Guidance Pavement Types Materials Design Factors Mix Design Structural Design Construction Pavement Evaluation Maintenance and Rehabilitation

Introduction

This design catalog is intended to give general structural design and mix type selection guidance for some typical Hawai'i HMA pavements. It is organized by general purpose, with each use type being addressed on a different page. These guidelines are intended for use in lieu of other guidance or specification. They are not intended to supercede official guidelines or specifications.

Assumptions

Recommended structural designs use the basic assumptions and classifications discussed below. The limitations and applicability of these assumptions and classifications must be understood before using the recommended structural designs contained in this section.

Traffic

Traffic is classified in a broad sense only. There are many different traffic classification schemes available and traffic can vary widely in both make-up and volume. This design catalog uses the "vehicle manufacturer truck classification", which broadly divides vehicles into the three classes listed in Table 1.

Table 1: Design Catalog Vehicle Classification

Vehicle Category
Gross Vehicle Weight Range
Assumed ESALs
per Vehicle
Representative Vehicles
Cars and Light Trucks
0 - 14,000 lbs.
0.0007
cars, SUVs, pickup trucks, ambulances, delivery vehicles
Medium Trucks and Buses
14,001 - 33,000 lbs.
0.25
city cargo van, delivery truck, wrecker, school bus
Heavy Trucks and Buses
over 33,000 lbs.
1.00
semi tractor trailer, concrete mixer, dump truck, garbage truck,
fire truck, city bus
Note: This classification is different from the FHWA vehicle classification system

Subgrade

Subgrade soil conditions vary widely across Hawai'i. This design catalog section classifies soils into three broad categories based on strength and stiffness (CBR, , R-value, MR) as listed in Table 2. These categories are broad and should be used with caution. A subgrade should be categorized based on its strength or stiffness and not its soil type alone. For example, it is not enough to know that a subgrade is primarily classified as an SW in the Unified Soil Classification (USC) system, something must also be known about its strength or stiffness.

A Note on Extremely Adverse Subgrades
The "Poor" classification shown in Table 2 is meant to describe subgrades with low strength and stiffness values and/or high fines content. Extremely adverse subgrade conditions such as water saturated soil, standing water, organic peat and ash provide extremely poor support and do not meet the "poor" classification in Table 2. Paving over extremely adverse subgrades should be avoided if possible. If paving is necessary, a pavement designer and a geotechnical engineer should collaborate to develop a feasible pavement design.

Table 2: Design Catalog Subgrade Classification

Classification
CBR
R-Value
MR (psi)
Typical Description (by USC)
Good
10 or greater
25 or greater
20,000
Gravels, crushed stone and sandy soils. GW, GP, GM, SW, SP, SM soils are often in this category.
Fair
5 - 9
12 - 24
10,000
Clayey gravel and clayey sand, fine silt soils. GM, GC, SM, SC soils are often in this category.
Poor
3 - 5
5 - 12
5,000
Fine silty sands, clays, silts, organic soils. CL, CH, ML, MH, CM, OL, OH soils are often in this category.


Pavement Structure

Material Substitutions

Other Information

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