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Section 7: Pavement Design Categories

There are three pavement structural design categories:

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  1. “new” pavement design
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  3. pavement reconstruction design and
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  5. pavement rehabilitation design.

It is very important that the designer conduct an early investigation to determine which category applies to the project.

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Definitions

The following table lists the definitions for each pavement structure design category.

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Term

Definition

“new” pavement

A combination of a base and surface course placed on a subgrade to support the traffic load and distribute it to the roadbed for flexible pavements or a combination of a base and a PCC slab for rigid pavements.

pavement reconstruction

Construction of a new pavement structure, which usually involves complete removal and replacement of the existing pavement structure including new and/or recycled materials.

pavement rehabilitation

Resurfacing, restoration, and rehabilitation (3R) work undertaken to restore serviceability and to extend the service life of an existing facility. This may include partial recycling of the existing pavement, placement of additional surface materials, or other work necessary to return an existing pavement, including shoulders, to a condition of structural or functional adequacy.

NOTE: These definitions do not necessarily coincide with program definitions.



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Example of Conditions for Each Pavement Design’s Usage

“New” Pavement Design. The “new” pavement design category assumes a pavement structure is constructed from point “A” to point “B” and there is no existing pavement along the proposed route. It may include a new parallel roadbed, such as, when a two-lane highway is transformed into a divided four-lane highway.

Pavement Reconstruction Design. Pavement reconstruction design assumes there is an existing pavement along the projected route. It is further assumed the structural condition of existing pavement is in such deteriorated condition, removal of all or part of the existing pavement is necessary. Also, there is the possibility that adjustments to the vertical and/or horizontal alignment make reconstruction necessary.

Figure 2-8 provides a flow chart for the design process for new pavements or a full reconstruction.

Design process for flexible pavement rehabilitation. (click in image to see full-size image) Anchor: #AFAODWXWgrtop

Figure 2-9. Design process for flexible pavement rehabilitation.

Pavement Rehabilitation Design. Pavement rehabilitation design assumes there is an existing pavement structure along the project route. The vertical and/or horizontal alignment will not change significantly. Also, it is assumed the existing pavement structure possesses a degree of remaining life. More information can be found in the Flexible and Rigid Pavement Rehabilitation Training CD/ROMs. Refer to “Training” in Chapter 1, “Introduction,” for more information on these CDs.

Figure 2-9 and Figure 2-10 provide flow charts for flexible and rigid pavement rehabilitation design, respectively.

Design process for rigid pavement rehabilitation. (click in image to see full-size image) Anchor: #JXVONAUMgrtop

Figure 2-10. Design process for rigid pavement rehabilitation.


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