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29 tractors to submit information on the work being performed plexity also means that taking on the task of developing XML by subcontractors. schema for all bridge types is beyond the scope of the current The information being exchanged includes contract descrip- project. There will be a need to clearly define a manageable tive information and pay items with quantities provided by the subset of structure types to focus on. In order to make this agency, and subcontractor descriptive information and pay effort most productive, it is desirable to build upon existing item subcontracting information provided by the contractor. work that has been accomplished within the AASHTOWare program on Virtis/Opis, and on prior NCHRP studies that have addressed bridge specification. 4.4 Highway Bridge Structures The AASHTOWare Virtis/Opis Project provides a com- The topic areas for bridge structures included in Table 1 prehensive bridge domain which contains bridge descrip- spanned the full life cycle of a bridge--analysis and design, tions for the purpose of structural analysis for many bridge construction, inspection and load rating, management, oper- types. These types include steel plate girder, rolled beam and ations, and maintenance. Given the common data exchanges built-up multigirder superstructures, reinforced concrete that occur within and across these areas, three specific busi- tee-beam and slab superstructures, sawn timber multibeam ness processes within these areas were identified as good can- superstructures and precast, prestressed concrete I-beam and didates for XML schema: box-beam superstructures. Currently the Virtis/Opis soft- ware provides a reporting tool that produces an XML repre- Bridge Analysis and Design; sentation of the bridge domain. This XML information is Truck Permitting and Routing; and used with a dynamic XSL template generator to produce National Bridge Inventory (NBI) Reporting/Data Exchange. user-defined reports for viewing using an Internet browser. The NCHRP Project 12-50 process provides a start for the Each of these candidates is discussed below. definition of Bridge Specifications information. This process is currently being applied in research on several NCHRP bridge-related projects. Bridge Analysis and Design The major candidate within the bridge structures area for Truck Permitting and Routing inclusion in TransXML is a physical description of the bridge geometry and structural characteristics. This information is Each state has procedures for issuing permits to vehicles developed during the structure analysis and design phase, and which exceed established size or weight limits for travel on then it is used throughout the bridge life cycle for develop- state highways. A number of different permitting and routing ment of load ratings and as input to permit and routing appli- applications are in place to select a permissible route for a cations (see below). vehicle based on the vehicle's characteristics (length, axle A standard XML format for describing the structural ele- configuration and weight) and the characteristics of the road ments of a bridge would facilitate use of multiple design and network--including bridge horizontal and vertical clearances analysis packages for a given design problem. According to and load ratings. A standard packet of information about the AASHTO LRFD specification commentary, the verifica- bridge characteristics required for permitting and routing is tion of computational processes used for bridge analysis is the a logical candidate for an XML schema. responsibility of the engineer. Because of the large amount of specification checking required for a single structure, verifica- NBI Reporting/Data Exchange tion of a process is not always simple. Hand checks are not always practical because of the iterative nature of many of The Recording and Coding Guide for the Structure Inven- the specification checks. Passing information, both bridge tory and Appraisal of the Nation's Bridges defines a standard description (input) and analysis/specification results (output), data structure for required annual NBI reporting on all pub- is often desirable to expedite the comparison of two processes. lic highway bridges. The current reporting format is a fixed In addition to having a standard description of the bridge format text file. NBI data is produced by bridge management for input to design and analysis software, it would also be systems (including AASHTO's Pontis system) and many state useful to have a standard format for representing outputs of DOTs have developed NBI reporting utilities that work with a bridge analysis. This would facilitate comparisons of the their bridge databases. NBI data is shared across different structural analysis results across different bridge software agencies and is used for a variety of analyses. applications which may have different output formats. Developing an XML schema for NBI data would provide a The complexity of bridge structure description informa- self-documenting format for NBI data and would provide a tion makes it a good candidate for XML; however this com- much-needed opportunity to address longstanding problems