Performance-Related Specifications for Pcc Pavements. Volume Iv: Appendix G-Pavespec 2.0 User Guide

PaveSpec is designed to develop and demonstrate performance-related specifications (PRS) for jointed plain concrete pavements (JPCP).   The software has specifically been designed to help State highway agencies (SHA’s) determine performance-related pay factors (and pay adjustments) for JPCP highway pavements.  PaveSpec was written in support of the Federal Highway Administration (FHWA) project titled "Laboratory/Field Investigation of Performance-Related Specifications for PCC."  For further information about the theory and practice of PRS, consult the project report (FHWA Report Nos. FHWA-RD-98-155, -156, and -171).

The software is driven by a simulation engine that is used to simulate pavement performance and associated life-cycle costs (LCC’s) for both as-designed and as-constructed pavements.  PaveSpec 2.0 allows the user to express pavement performance in terms of the following distress indicators:

• Transverse slab cracking.
• Transverse joint faulting.
• Transverse joint spalling.
• Pavement smoothness over time—Present serviceability rating (PSR) or International Roughness Index (IRI).

Each of the distress indicator models is a function of many variables, including one or more of the following five acceptance quality characteristics (AQC’s):

• Concrete strength.
• Slab thickness.
• Entrained air content.
• Initial smoothness.
• Percent consolidation around dowels.

Using the current PRS approach, lot pay factors are then computed based on a comparison of the simulated LCC’s for the as-designed and as-constructed pavements

What Can You Do With PaveSpec? 

Before one can effectively use PaveSpec to develop PRS-based specifications, it is important to understand the major capabilities of the software.   Currently, the software is divided into two different parts that allow the user to accomplish the following tasks:

• Develop a specification—The program’s Specification Wizard is used to develop project-specific PRS-based specifications.
• Use a specification—PRS-based lot pay factors (and pay adjustments) may be computed based on actual AQC field data.

The details of each of these two major software capabilities are described in chapters 3 and 4, respectively.

Data Organization

PaveSpec stores its data in files called databases.   Each database may be named and saved as a separate file to a disk. Databases are made up of smaller data elements called documents.  The three document types available in PaveSpec 2.0 are modules, specifications, and specification-dependent documents.

Modules

Modules are stand-alone sets of user-defined variables (of a similar type) that are independent of any particular specification. Descriptions of the different module types are as follows:

Pavement Design—This module contains pavement design-related input variables required by the distress indicator models.  Examples of the variables contained in the pavement design module include Pavement Type, Transverse Joint Spacing, and Dowel Bar Diameter.

Design Traffic—This module contains traffic-related information required to calculate yearly equivalent single-axle loads (ESAL’s) over the chosen analysis period.  Examples of variables contained in the Design Traffic module include Initial Year or Total Design ESAL’s, Traffic Growth Type, and Traffic Growth Rate.  (Note: Average daily traffic [ADT] may be used to compute first-year ESAL’s.)

Climatic Variables—This module contains climate-related input variables required by the distress indicator models.  Examples of the variables contained in the Pavement Design module include Freezing Index, Average Annual Number of Wet Days, and Climatic Zone.

Maintenance and Rehabilitation Plan—This module contains the step-by-step rules making up the maintenance and rehabilitation (M & R) plan.  The M & R plan is used to determine what type of M & R activities are to be applied to the pavement in response to the simulated distress indicators, and when those activities will be applied.

Unit Costs—This module contains unit cost information used to compute LCC’s resulting from the estimated M & R activities.  Unit costs are organized into maintenance, localized rehabilitation, and global rehabilitation costs.

There can be any number of each type of module defined within a database; however, only one of each type of module is specific to a developed specification.

Specifications

Specifications define all aspects of the PRS development procedure, including the developed PRS preconstruction output.  More than one specification may be developed and saved within each database.  A specification document is developed by completing all of the steps in the PaveSpec Specification Wizard.  When developing a specification, the user is required to select (or define) modules for each of the five module types.  That is, for each specification, the user indicates which Pavement Design, Design Traffic, Climatic Variables, Maintenance and Rehabilitation, and Unit Costs modules are to be used for estimating pavement performance and subsequent LCC’s.  This modular approach allows multiple specifications to be developed based on the same underlying assumptions.

Specification-Dependent Documents

The last type of document is the specification-dependent document.  This document type is further divided into two types of documents, referred to as use specification and drill-down documents.  Each of these specification-dependent document types is developed for a chosen specification.   If the specification is deleted, the dependent documents are also deleted.   The two specification-dependent document types are as follows:

Use Specification—The use specification documents contain actual AQC field sampling and testing data entered by the user.  A separate document is used for each project (i.e., data for multiple lots of the same project are entered into one use specification document).  The output report associated with this document type contains lot and project pay factor (and pay adjustment) summaries.

Drill-Down—This document type allows a user to view the performance (distress indicators) or LCC details of any selected simulated sublot that went into an overall simulated-lot LCC.  A simulated-lot LCC is typically the mean of 500 simulated sublot LCC’s, and the standard specification output report only contains a summary of these simulated-sublot LCC’s.  Therefore, if users want to see details of one of these specific simulated sublots, they must create a drill-down document.  The resulting document provides detailed performance, M & R, and LCC information at the lot and sublot level.  This type of document is very helpful when trying to understand project-specific interactions between performance and LCC’s.