4-1INVENTORY & HISTORY4.1 Module ObjectivesThis module will define what types of inventory and historical data should becollected, how it should be collected and how it is used in a PMS. Differenttypes of data collected will be discussed as well as an introduction to groundpenetrating radar for use in data collection. Upon the completion of thismodule, participants will be able to accomplish the following:■ Define types of inventory and historical data necessary for use in a PMS■ Be aware of different methods of collecting data■ Understand the use of ground penetrating radar (GPR) in a PMS to supplementconstruction layer history.■ Understand the importance of drainage on the structural adequacy of the pavement.■ Develop and use strip maps.■ Understand the importance of quality control (QC) on data collected.4.2 Types of Inventory DataOne of the most important steps in the implementation of a pavement managementsystem (PMS) is to develop an inventory of the pavement network. The inventoryprocess is the foundation of a PMS, and must be developed with a well-defined plan forthe use of each and every data element collected. To provide the PMS administratorwith the support needed in the decision-making process, it is important to determinewhat data needs to be collected, how the data will be used, and how and when the datacollection will be done. This ensures that the types of data collected can be used in thedecision-making process, and eliminates the collection of needless data that is costly inboth dollars and time.Several factors should be included when deciding what data to collect:■ What decisions are going to be made■ What data is necessary to make those decisions■ Size of pavement network■ Type and characteristics of the agency■ Type and cost of data acquisition and processing■ Required accuracy of the data■ Required frequency of data collection■ Database capabilitiesData collection should be separated into two levels. The network-level data shouldanswer the general planning, programming, and policy decisions supported by thenetwork-level PMS. The project-level data should support decisions about the besttreatment to apply to a selected section of pavement. As data are collected, selectedelements can be stored to create a more complete database over time. However, a planmust be developed to keep that data current.INVENTORY & HISTORY4-2Only data elements needed to support decisions at the network-level should becollected at the network-level. Detailed data will be needed at the project-level and canbe collected when the project-level analysis is completed.When deciding what data to collect, there are two simple rules-of-thumb:■ Collect only the data you need!■ Collect the data only when you need it!Decision-making policies should be supported with data that are:■ Relevant■ Reliable■ Cost effective to collect■ Cost effective to maintainTypically, when an agency decides to implement a PMS, the first issue to be addressedis what kind of data should be collected. Usually, this is done through a committeecomposed of various personnel who will sit down and develop a “wish list” of datathey would like to collect. Another common approach is to try to use data that alreadyexists to build a PMS. Experience has shown that neither of these methods is effectivewhen trying to design the inventory database of a PMS. Some hazards of defininginventory needs in this manner result in attitudes like “it would be nice to have thedata” or “it might be useful someday.” Data collection is time-consuming, expensiveto store, and expensive to analyze. Sifting through needless data will result in a slow,cumbersome PMS and a lot of wasted dollars.The inventory will require a minimum number of data elements in order to be effectiveand will include some historical data. A typical PMS inventory at the network-levelwill include the following types of data (1,5,6):■ Section identification (see following section)■ Location - defines start and stop points (milepost, cross-street, etc.)■ Geometrics■ Pavement structure, construction and maintenance history■ Cost■ Traffic■ Drainage information■ Environmental data■ Proposed work or work-in-progress■ Other informationGEOMETRICS: The geometry defines the physical characteristics or features of the pavementsections. It can include lengths and widths of the section, functional classification (e.g.principal arterial, interstate), number of lanes, median width, shoulder width and type,cross-slopes, grade and curvature, and the presence of curb and gutters. This data isgenerally used in planning major rehabilitation projects to determine if reconstructionis required based on geometric considerations.INVENTORY & HISTORY4-3PAVEMENT STRUCTURE, CONSTRUCTION & MAINTENANCE HISTORY: In order to fulfill its purpose, a PMSmust follow through from planning and programming design to implementation,including construction and periodic maintenance. Construction, of either a newpavement or rehabilitation of an existing pavement, converts a design recommendationinto physical reality. Loss of performance, eventually leading to a need forrehabilitation, is identified within an ongoing process of data collection and evaluation.Such evaluation of pavement performance is also used for determining the currentstatus of the pavement network..Construction history is needed to identify the surface type and age of a pavementsection. Maintenance and rehabilitation treatments that have been applied to thepavement are important not only for predicting how much remaining life a pavementmay have, but also for predicting how well a treatment has performed.For some agencies, the only pavement structure data available is the type of surface.This is inadequate for a good PMS. At the other extreme are systems that containcomplete construction details of the pavement construction history. Pavementconstruction data includes information on the as-built properties of the materials, suchas the results of concrete flexural strengths and asphalt concrete densities. Largevariability of construction quality will result in poor performance.In some cases, construction data will not be available in any form. If that occurs, thepavements can be cored or trenched to examine the structure. Generally, it is notnecessary to have a separate program of coring to establish the pavement structure.The data can be collected as part of a