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18 SAFETEA-LU. Specific guidelines for decks include the fol- DOTs are developing based on selected NBI rating items lowing (Lwin 2007): (see chapter three for examples of these indexes). Because a single agency deals with a smaller number of bridge designs · Such bridge work is to be considered rehabilitation and construction materials than those encountered nation- under the HBP regardless of the bridge's SR. wide, state DOTs are able to subdivide their bridge popula- · Although the 10-year rule will not prevent federal tions more easily into distinct groups for which modeling funding of deck rehabilitation or replacement, once becomes more practical. this work is performed, the 10-year rule will apply. · Deck rehabilitation or replacement projects should be A needs forecasting model has been developed for use identified systematically, in conjunction with a com- with the entire nationwide NBI database. The FHWA applies prehensive BMS, to use federal and other bridge funds this predictive tool, NBIAS (National Bridge Investment wisely. Analysis System), when preparing its bridge-related needs · This bridge-deck eligibility does not relieve the bridge estimates for submittal to Congress in the biennial Condi- owner of having to perform other work needed to tions and Performance reports. NBIAS draws on the infor- restore bridge structural integrity or to correct safety mation in the complete NBI database and on a set of unique deficiencies. analytic techniques based in part on the methodology and data in Pontis, a full-featured BMS used in more than 40 This clarification addressed several concerns expressed state DOTs (e.g., for element-level deterioration models and in 2007 congressional testimony regarding the eligibility of default values of required data such as unit costs). Users structurally deficient bridge decks for HBP funding. The key may specify key input parameters such as standards for points that were presented in this testimony are discussed in bridge structural preservation and functional improvement. Chapter 4. The predictive models for bridge deterioration require ele- ment-level data describing the bridge network, informa- Predictive Models for NBI Measures tion much more detailed than that in the NBI database. For example, element-level data would require descriptions and The NBI condition and performance ratings are aggregate condition information on each bridge girder rather than a measures, sufficiently general to apply to the many combi- single numerical rating for the entire superstructure as in nations of bridge designs, materials, traffic loadings, and the NBI database. NBIAS therefore incorporates a unique geographic locations throughout the country. It is therefore set of Synthesis, Quantity, and Condition (SQC) models difficult to develop a general set of predictive models that that draw on current NBI data to estimate the quantity and could apply to the many different bridge configurations condition of all the bridge elements in the NBI--that is, nationwide. the element-level data are "synthesized" from the NBI data. SQC models were derived from a statistical study of more This form of bridge management [based on NBI data] utilizes aggregated information and thus has limited than 10,000 bridges representing structural and materials applicability for analytical decision making. While configurations from throughout the country. NBIAS has the formula is convenient for funds allocation, it is not continued to be enhanced since its initial use in the 1999 necessarily sufficient for analysis and needs prediction. Conditions and Performance report to permit greater user ... A new form of bridge management decision support to facilitate budgeting, policy analysis and project- flexibility and to improve the reliability of its estimates programming [came to be] desired (Small et al. 1999, p. (FHWA and FTA 2006). A-1/2). Today's BMSs, which are alluded to at the end of the pre- Bridge Management Systems ceding quotation, employ more detailed descriptions of bridge elements and individual deterioration models for each group Background of elements. These systems are discussed in the next section. Development of new BMSs with more advanced decision- A few DOTs have sought to take advantage of the wide support capabilities began in the United States in the 1980s coverage, ready availability, and rich content of their NBI and continued through the 1990s. BMS designs and imple- database by formulating predictive models tailored to their mentations were pursued independently by several DOTs, own state practices and geographic conditions. In some including North Carolina, Pennsylvania, Kansas, New York, cases, these models predict the change in NBI ratings on a Indiana, and Texas. The FHWA sponsored a demonstration scale of 0 to 9 (Michigan DOT, see Juntunen 2003) or the project that led to the development of Pontis (Small et al. numbers of bridges in different SR intervals (Louisiana 1999). Today, Pontis is an AASHTOWare product main- Department of Transportation and Development; see Sun et tained as part of AASHTO's BRIDGEWare suite, and is used al. 2004). In other cases, yet newer models are being esti- by more than 40 state DOTs plus other transportation agen- mated for uniquely defined bridge indexes that individual cies. DOTs that are not Pontis licensees may employ state-
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19 specific systems. Agencies in other countries likewise have · A report of bridge NBI ratings Structure, Inventory, the option of licensing Pontis or developing their own BMS. and Appraisal (SI&A) and load testing by structure. Examples of two U.S. BMSs that illustrate two ends of the A supplementary report provides historical trends in analytic spectrum at which these systems operate follow. NBI ratings for a structure. · A report listing bridges by their SR priority. Alabama Bridge Information Management System · A list of bridges scheduled for inspection, with inspection due date. System Description · A list of bridges showing current maintenance needed. Some BMSs focus on database management--for example, · A list of bridges showing their current posting status. input, quality checking, and processing of bridge data, and · A list of bridges indicating those with data errors that production of reports. The Alabama Bridge Information have been identified in the FHWA edit report. Management System (ABIMS) provides a series of bridge · A report relating bridge projects to road projects inventory and inspection menus by which users may input identified in the agency's construction project manage- bridge descriptive information and inspection data. Another ment system, identifying bridge replacement projects set of menus allows users to specify reports on, for example, and other types of projects (e.g., bridge painting). bridges due for inspection, status of maintenance, bridge · Reports on specific bridge characteristics; for exam- posting status, the rating history of a bridge structure, a vari- ple, engineering and site conditions for scour-critical ety of inventory listings, and priority ranking. The criterion bridges. for priority ranking may be specified as either the FHWA SR or the state's unique Deficiency Point calculation. The latter If an agency has defined its own measure of condition and report may be tailored according to Deficiency category--for performance, an additional set of reports likely will be avail- example, Total Deficiency, Load Deficiency, Vertical Clear- able to display this information. In this example for Alabama ance Deficiency, Width Deficiency, Condition Deficiency, DOT, the ABIMS system provides a list of bridges by prior- and Statewide Deficiency (Alabama DOT 2006). This exam- ity in terms of several categories of Deficiency Points: Total, ple illustrates one measure of value of a BMS: the ability to Load, Vertical Clearance, Width, Condition, and Statewide. address unique aspects of bridge operation and customized features of bridge management. ABIMS is able not only to cal- A manager can tailor the ABIMS reports to focus on par- culate Deficiency Points from NBI inspection data (together ticular areas of interest. These may be geographic (district, with SD, FO, and SR), but also to accommodate nonstandard city, or county); for certain reports, the particular bridges to legal loads in its bridge load rating calculations. be shown (e.g., identified by Bridge Identification Number or by route-milepost limits); for inspection and maintenance Reports reports, the inspection responsibility code or the maintenance responsibility code for which records are to be displayed; the The ABIMS database is a repository of descriptive informa- type of inspections to be displayed (e.g., those on 24-month tion on bridge structural characteristics, traffic loads, geo- intervals versus intervals less than 24 months); the specific graphic and route location, functional class, and age, as well maintenance activities to be displayed; for reports on histori- as current and historical records of inspection data. NBI data cal records, the years to be displayed; and so forth. are included for annual reporting to the FHWA, and cus- tom data defined by the agency are also included. Standard All of these reports represent current or historical snap- reports focus on breakouts of bridge characteristics, bridge shots of bridge status. Some categories of reports, such as condition, and information on related management tasks those related to identified bridge needs and actual mainte- such as inspection and maintenance. Following are examples nance work performed, or reports related to explanations of of the types of reports that are available: bridge engineering characteristics, may be available in both summary and detailed formats. Because the BMS has no · Separate reports presenting a complete list of bridges predictive models, there are no forecasts, scenario analyses, currently in the inventory, a list of structures catego- or other future-oriented reports. rized by current operational status (e.g., now in design or construction, in service, or out of service), Pontis and a list of bridges organized by special categories (e.g., those with underwater substructure, those with System Overview fracture-critical members, and those with certain NBI structural condition, waterway adequacy, and scour Pontis was developed for the FHWA in 1989 and is now sup- ratings of 3 or less). Inventory cross-referencing ported through AASHTOWare as a product in AASHTO's information is listed on another report. BRIDGEWare suite. It is licensed as of 2008 to DOTs in · A list of bridges by route. more than 40 states and the District of Columbia, as shown
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20 in Figure 3 (Johnson 2008), plus several city, county, and Representation of Structural Elements international agencies. It is a full-featured BMS that pro- vides a number of capabilities useful in supporting bridge Pontis describes bridge and culvert structures in more program management and resource allocation (Cambridge detail than the NBI offers. Bridges are expressed in terms Systematics, Inc. Jan. 2005b): of their structural elements. Some examples for different types of bridges include girders, stringers, and beams; truss · Bridge Inventory: Establish and maintain an inventory components; arches; pin and hanger assemblies; deck and of bridge and culvert information, and exchange data deck slab; railings and traffic barriers; deck joints; bear- with other agency information systems. ings; piers and columns; abutments, approach slabs, and · Managing Inspections: Schedule bridge inspections, wing walls; and footings and pilings. These elements may enter or importing inspection data, produce SI&A and be described for bridges as a whole, or within sections with other inspection reports, and produce the NBI files that varying characteristics termed "structure units," as illus- are required to be submitted to the FHWA annually. trated in Figure 4 (Cambridge Systematics, Inc. 2005b). By · Needs Assessment and Strategy Development: Estimate contrast, the NBI would represent the bridge structure in and update bridge element deterioration and treatment Figure 4 by the more general components of superstructure, cost models based on individual agency experience; substructure, and deck. develop long-range, network-level policies for both structure preservation and bridge improvement based Pontis' analytic approach is built around structural ele- on agency standards or guidelines and economic fac- ments. A brief discussion helps to illustrate the difference tors, including agency and road-user costs; assess cur- between element-level descriptions of bridge condition ver- rent and future preservation and improvement needs; sus the NBI ratings described earlier. Some examples are and evaluate alternative bridge program investment as follows: scenarios based on predicted structure condition and performance, accounting for the technical, economic, · Bridge inspections are conducted at the element and policy-related factors described previously. level. AASHTO has formalized these inspection · Project and Program Development: Develop projects procedures within its guide for "commonly recog- to respond to inspector work recommendations and nized" (CoRe) elements (AASHTO 1997). Although agency policies and standards; evaluate the impacts this guide was based on the Pontis approach, it has of project alternatives on structure performance; rank been generalized to apply to other BMS in addition to projects; develop programs of projects subject to budget Pontis. Agencies may also define their own elements constraints; and track project status and completion. within Pontis. FIGURE 3 U.S. state agencies licensing Pontis as of 2008 (Source: Johnson 2008).
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21 FIGURE 4 Structure units and elements in Pontis (Source: Cambridge Systematics, Inc. 2005b). Note: PS = painted steel; RC = reinforced concrete. Some agencies inspect bridges at the element level and Do Nothing, or Clean and Paint, or Reset Bearings, then apply a Translator program in Pontis (developed and/or Rehabilitate Supports; CS-3, advanced cor- for the FHWA) to convert element-level data to the for- rosion: either Do Nothing, or Rehabilitate Supports mat required for NBI submittals. Other agencies con- or Bearings, or Replace the Bearing Unit. duct dual inspections, recording bridge conditions at · Bridge deterioration models and cost models are defined both the element level and in NBI format. State DOTs by the Pontis user for each element. Deterioration mod- also may develop supplementary inspection guides to els are expressed through transition probabilities that accommodate state-specific bridge, traffic, or other describe the likelihood of an element condition chang- data requirements. ing from one condition state to another in a simulated · Structure condition is defined at the element level in cycle. Pontis users may estimate these probabilities terms of up to five discrete "condition states." The when first applying the BMS, and later update them best condition is specified in condition state 1, and the when historical data on element deterioration are avail- worst condition in the last condition state (condition able. Preservation costs are expressed for each defined state 3, 4, or 5, depending on the element). The per- treatment or action by element and condition state. centage of each element in each condition state is com- Pontis users may enter costs of bridge improvements-- puted by Pontis in each time period and is available in for example, for bridge widening, strengthening, or a report. This breakdown describes the condition dis- raising to improve vertical clearance. tribution of that element, allowing a manager to get a · Bridge elements may be located in different environ- better perspective on the magnitude of network-level ments, which might influence rates of deterioration. deficiency. CoRe elements have predefined condition The following environmental regimes are defined in state descriptors. For example, the condition states for Pontis (Cambridge Systematics, Inc. 2005b): element 152, Painted Steel Floor Beam, and element Benign--No environmental conditions affecting 313, Fixed Bearing, are as follows (condition states are deterioration identified using a CS number convention): Low--Environmental conditions create no adverse Painted Steel Floor Beam: CS-1, no corrosion; CS-2, impacts or are mitigated by past actions or highly paint distress; CS-3, rust formation; CS-4, active effective protective systems corrosion; CS-5, section loss Moderate--Typical level of environmental influ- Fixed Bearing: CS-1, no deterioration; CS-2, minor ence on deterioration deterioration; CS-3, advanced corrosion Severe--Environmental factors contribute to rapid · Up to 10 preservation treatments or actions may be deterioration. Protective systems are not in place or defined at the condition state level for each element. are ineffective. Pontis users may apply default actions or define their own preservation treatments. Analytic Processes Actions may range across alternatives such as Do Nothing, Routine or Preventive Maintenance, Minor Pontis' analytic processes are extensive and address several Element Repair, Major Element Repair, Element aspects of bridge management. Their descriptions are con- Rehabilitation, and Element Replacement. tained in system documentation (Cambridge Systematics, A specific example by condition state for element Inc. 2005a, b; FHWA 2007d). An overview of the sets of 313, Fixed Bearing, is as follows: CS-1, no deteriora- procedures, which are organized in "modules," is shown in tion: Do Nothing; CS-2, minor deterioration: either Figure 5.
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22 FIGURE 5 Overview of Pontis' analytic processes (Source: Cambridge Systematics, Inc. 2004). The review and analysis of bridge data, including bridge of benefits versus costs and the resulting condition of the inventory and inspection data, is handled through the Inspec- bridge network. tion module, which works with the database that is used in connection with Pontis. The data encompass the standard The results of a Pontis simulation can be expressed in sev- or default bridge elements and descriptors, the standard eral ways (Cambridge Systematics, Inc. 2004): NBI data, and any custom data that the bridge manager has defined. The NBI Translator program may be applied to con- · Condition distributions of structure elements vert element-level data to the format required by the FHWA · Predictions of structure needs and work that is pro- for NBI submittals. Other available processors include the jected to have been accomplished SR program, which computes SR, SD, and FO status, and · The Pontis Health Index, which is the ratio of the cur- the Validation program, which conducts edit checks of the rent value of all structure elements (based on their cur- most recent NBI data. rent distribution of condition states) as compared with the total value of all elements (assuming all are in their Pontis conducts a comprehensive analysis of bridge pres- best condition state) ervation options to recommend a preferred strategy. This · Benefits to both agency and road users as the result entails definition of a preservation policy for each combina- of preservation and improvement actions; for exam- tion of bridge element and environment. Other data items are ple, monetized benefits owing to improvements in also defined, including (1) treatments for each element and the Health Index, and road-user benefits in terms of condition state, (2) corresponding unit costs, and (3) other reduced travel time, vehicle operating, and accident- technical and budgeting parameters. Similarly, specifica- related costs as the result of bridge improvements tion of an improvement policy entails providing guidelines · NBI condition ratings for deck, superstructure, sub- and costs for different types of bridge improvements; for structure, and culvert; deficiency status (SD, FO); NBI example, widening and increasing clearances. Separate sim- appraisal ratings; and calculation of the NBI SR ulations and decision-support procedures are conducted for · Other measures, including the Health Index of subsets these two types of investments at the network level through of elements, eligibility for HBP funding, and detail the Pontis Program Simulation module. The network-level information for individual structures. simulation accounts for the effect of budget constraints and supports estimates of bridge needs and decisions in pro- The Project Planning module focuses on projects for indi- gramming, resource allocation, and budgeting. These analy- vidual bridges. Projects are developed from results of the ses estimate impacts of future bridge investments in terms network-level analyses and from work candidates recom-
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23 mended by bridge inspectors. Projects can be assembled into tor of the most recent regular and special inspections, programs. Once programs are defined, further network-level and planned dates for the next inspections. analyses can be run to refine results--for example, by vary- · The Inspection Resource Requirements report ing the characteristics of scenarios, running what-if analy- provides the dates of the last and the next scheduled ses, and adjusting policy specifications and costs to match inspections and planned resources needed in terms of agency business processes more closely. estimated hours for the inspection crew, flaggers, help- ers, snoopers (trucks with inspector baskets on articu- Results can be viewed in reports as described here. lated, telescoping arms that can reach overhead or under a bridge), special crews, and other special equipment. Customization Options · The Bridge Health Index displays the current Pontis Health Index for selected bridges plus detailed infor- The ability to customize BMS features will be shown in mation about the condition distributions of bridge ele- chapter three to be an important aspect of BMS usefulness ments that are used to calculate the Index. and acceptability. Pontis has features dedicated to incorpo- · The Bridge Condition Summary shows, for each rating user-defined additions or revisions within its analytic selected facility, the most recent inspection date, the framework and graphical user display. A number of items SD and FO rating, the SR, and NBI ratings for the deck, may be customized, including the definition and classifica- superstructure, substructure, culvert, and channel rat- tion of bridge elements, the definition and classification of ing items. bridge actions, the cost index that is used, internal formu- · The Network Element Summary shows the network- las for data processing, and organization of the desktop and wide distribution of bridge elements by environment assignment of user privileges. Features such as data input and condition state. forms and reports may be customized to accommodate the analytic revisions. Two reports present the results of the network-level mod- eling of Bridge Preservation: Reports · The Unconstrained Needs report displays the costs and benefits of the optimal preservation policy as applied to Pontis presents a broad selection of standard reports, reflect- the bridge network when unconstrained by budget lim- ing its extensive features and functionality. The reports are its. The effect of the budget constraint is shown, how- organized by system modules and include the examples ever, in the distinction between those recommended listed here. Reports are available in metric or English mea- projects that are "programmed" by Pontis (i.e., allowed surement units. If a report pertains to a given structure (as by the budget limit) versus those that are not. opposed, for example, to summaries for a bridge network), · The Preservation Details report identifies the recom- the bridge(s) may be selected using Pontis' Select Struc- mended actions for each element in each type of envi- ture screen, which selects bridges by district, county, owner ronment and condition state, and compares the current agency, custodian agency, function class, NHS or non-NHS, distribution of bridge elements versus the distribution defined administrative area, defined bridge grouping, or that would result from the optimal preservation policy inspector responsibility. These descriptions are adapted applied over the long term. The report also provides the from the Pontis Release 4.4 User Manual (Cambridge Sys- details on unit cost of each action, and the transition tematics, Inc. 2005b). probabilities that were used in the deterioration model to determine the optimal policy. Inspection Reports present information on the bridge inventory, current and historical information on bridge con- In addition to the bridge preservation results cited pre- dition and performance, and inspection schedules. Example viously, several standard reports provide information on reports include the following: Bridge Needs and Projected Work: · The SI&A sheet lists for each bridge the NBI SI&A · The Bridge Management Summary reports the cur- information, element-level condition data, and past rent requirements of the bridge inventory in terms of inspection comments. estimated future needs and programmed work by year. · The Expanded SI&A report includes notes recorded It helps managers to determine whether current invest- by the inspector regarding a bridge, bridge element, and ment levels can meet the optimal long-term investment inspection; work candidates specified by the inspector; policy recommended by Pontis. and summary information on past inspections. · The Backlog Summary displays the annual budgeted · The Inspection Schedule gives inspection planning amounts versus the backlog of unmet needs by year and scheduling information, including the frequency and work category: preservation, replacement, and of regular and special inspections, the date and inspec- improvement/other work.
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24 · A series of reports displays the costs and benefits of · The Project Priority List displays projects sorted by needed work and programmed work for the bridge program, year, and Pontis Program Rank. Managers network by year in different formats--for example, may select a single year, a single project status (i.e., for each element or set of selected elements; for each Initiated, Programmed, Deferred, In Progress, element, grouped by element category; for different Completed), or an individual program to be displayed. combinations of element category and material type; If these fields are left blank, all projects will be selected. for each district, functional class, on/off NHS, and The Pontis Program Rank may be based on project on/off system classification; for each district and each benefits, costs, benefit-cost ratio, average Health Index, scenario; for all combinations of values of district, SR, or Agency Rank (e.g., a numerical score computed functional class, on/off NHS, and on/off system clas- by the agency or a district-provided ranking). sification; and overall costs and benefits by year. · The Pontis Priority List displays Pontis-generated · Two reports on performance measures: a Bridge work candidates for a selected scenario and one or Performance Measures report that displays perfor- more selected years. mance measures by structure and year, and a Network · The Pontis Candidate List displays Pontis-generated Performance Measures report that displays perfor- needs or work candidates for a selected set of bridges. mance measures for all combinations of values of dis- Managers may select the groups of work to be included trict, functional class, on/off NHS, and on/off system based on year, costs and benefits, whether work was classification. programmed by the selected scenario, whether the · A Scenario Report displays the specifications for the work was assigned to a project, and other items avail- currently selected scenario. able in the Pontis work-related data. · The Project Details report is a one-page-per-project Project Reports produce information related to individ- display of all information provided on the project data ual bridge structures: entry forms, including a list of work items. Projects may be selected for this report based on project ID, pri- · The Preservation Needs report displays preservation mary action type for the project (e.g., Replace Element, needs for individual structures that Pontis has gener- Overlay Deck, Replace Paint, or Replace Structure), ated for the currently selected scenario, and an indi- the year for which the project is programmed, the proj- cation of whether or not they have been programmed ect status, the program ID, and the district, route, and by the simulation. By selecting a particular year to milepost/kilometer-post. display, a manager can identify whether needs for · The Actual versus Budget report compares the dol- specific bridge(s) have been programmed (i.e., recom- lar value of programmed work by year to the annual mended as work candidates when budget constraints budget that has been established for that program. The are considered). manager can specify the projects to be included in the · The Work Candidates and Projects report displays programmed work totals in terms of project status cri- the proposed projects, inspector-specified work can- teria (i.e., one or more of the project status designations didates, and Pontis-generated work candidates for all listed previously). scenarios for a selected set of bridges. This report is · The Program Funding report displays the fund- useful to determine which work candidates have been ing sources and amounts by year for each active addressed by projects. program.