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29 Table 24. Emergency--frequent uses of activities. Emergency Bridge Components Post Bridge, Deck, Superstructure, Substructure, Culvert, Movable Span. Bridge, Deck, Joints, Drains, Parapets/Railings/Sidewalks, Superstructure, Bearings, Shore Substructure, Approach/Embankment, Channel (bank), Culvert, Movable Span. Closure, partial Bridge, Culvert, Movable Span. Closure, full Bridge, Culvert, Movable Span. Detour Bridge, Culvert, Movable Span. Temporary Bridge, Culvert, Movable Span. bridge and culverts; Temporary applies to bridges and culverts. A list duction and Resources), two tables contain inventory data of likely applications of Emergency activities with bridge com- (Structure and Roadway), three tables contain bridge inspec- ponents is shown in Table 24. tion information (Inspection_Cross_Reference, Element_ Inspection, and Inspection_Event), three tables define the correspondences between NBMD data entries and DOT NBMD Database data entries (Activity_Definition, Element_Definition, and NBMD is a modular self-contained historical record of Resource_Definition), one table identifies data sources (Con- maintenance work at bridges. NBMD is a ledger of bridges, tact), one table lists element-level unit costs of maintenance bridge conditions, work performed, resources expended, and (Element_Unit_Cost) and one table provides file size informa- costs. NBMD is a collection of datasets of identical structure tion used by NBMD software applications (Size). The tables (Figure 3). All information on maintenance actions, their costs, are linked through global identifiers for bridges, mainte- the bridges affected, and the outcomes are contained in a data- nance events, and definitions for actions, bridge elements, set. Each dataset contains information from a single DOT and and resources. a fixed reporting period. Maintenance production is recorded as Events. An event is Each NBMD database is a collection of 13 tables (Figure 4). defined as a set of work activities conducted at the same time on Of these, two tables contain maintenance work data (Pro- a single structure. Each event provides a specific maintenance Figure 3. National bridge maintenance database.

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30 Figure 4. NBMD dataset organization. Operation and one bridge Component. Each event is asso- immediate or at least near-term re-evaluation of element con- ciated with bridge inspections before and after the event. ditions after maintenance is not usual. In response, NBMD Inventory data are recorded for the structure and the road- identifies and stores bridge condition data from inspections way. A Resource is a quantity of labor, material, equipment, that occur before and after maintenance events. or contract pay item applied in the accomplishment of an NBMD collects data from existing sources at DOTs includ- action. ing NBI files, Pontis bridge databases, maintenance manage- ments systems, and reporting systems for labor, materials, and equipment. NBMD identifies appropriate data fields in DOT NBMD Data Sources sources. NBMD moves unmodified DOT data to appropriate NBMD contains data adequate for computation of total storage areas in NBMD data tables and augments DOT data costs and unit costs, generation of reports of maintenance with NBMD keywords. The NBMD keywords provide the uni- accomplishments, creation of performance standards, and form reporting and retrieval features that make any DOT's evaluations of maintenance actions. NBMD preserves the his- data useful to all DOTs. The paths of DOT data into NBMD tory of maintenance events so that long-term performance datasets, and the potential for sharing of NBMD datasets of actions can be examined, life-cycle costs can be computed, through internet sites is shown in Figure 5. and the evolution of maintenance programs can be tracked. Data include the following: Data Integrity Crew card data in all headings: Work Administration, NBMD is a long-term repository of bridge maintenance Work Performed, Location, Labor usage, Equipment data. For this reason, datasets are self-contained. Datasets are Usage, Material Usage, Work Production. complete with all bridge inventory and condition data and all Quantities of affected bridge component or element. maintenance action, accomplishment, resource and cost data. Bridge conditions before and after the maintenance event. Changes over time to bridges (as by modification or replace- Total cost and unit costs of maintenance. ment), inventory and condition data (by new coding formats), or maintenance data (by introduction of new methods or While data from crew cards and contract tabulations are materials) will not affect the historical record and will not routinely available, other data may not be. The field collec- limit the future ability to retrieve and understand the histori- tion of element-level maintenance quantities is not usual. The cal record.