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51.1 Research Context Need for Transportation Data Exchange Standards The need for development of common data standards and simple data exchange mechanisms within the transportation domain has long been recognized. Transportation agencies make use of a variety of data sets and software tools to support planning, design, construction, maintenance, and operations activities. Tools within each area are specialized, with data requirements tailored to the specific function being performed. However, there are natural connections across the life cycle of activities that create the need for information flows across indi- vidual applications. From the perspective of an individual proj- ect, information developed in one phase becomes a starting point for the next. Designers build on the efforts of planners, construction managers begin with the work of the designers, and then maintenance and operations managers begin with as-builts and other information produced in the construc- tion phase. Information also needs to flow in the reverse directionâfor example, designers should ideally learn about the constructability, maintenance requirements, and safety (via crash records) of a particular design approach. There also are important horizontal flows of information within particular phases of the transportation facility life cycle. For example, design of a roadway alignment involves consid- eration of bridge geometry, retaining wall design, drainage structures, traffic volumes, and right-of-way acquisition impacts. The efficient integration of all these facets of road- way design can provide early feedback to designers, which in turn can have profound effects on the cost and timing of the project. New approaches like design-build can fast-track the process, putting even greater demands on the efficient flow of information. Tighter budgets necessitate better design effi- ciency to minimize construction costs. Increased reliance on software in many areas begs for more automated approaches for moving data from one application to the next. Ideally, there would be seamless connections across sys- tems to facilitate data exchange, but this is the exception rather than the rule. For example, planners assemble a vast amount of information about a project as it moves from the Statewide Transportation Improvement Program (STIP) to preliminary design. Instead of building upon this informa- tion, the designer begins with a clean sheet of paper. One rea- son for this is the incompatibility of the plannerâs Geographic Information System (GIS) and the designerâs Computer- Aided Design (CAD) system. As the facility moves to con- struction, information is manually extracted from the design plans into the construction management system, wasting time and inevitably introducing errors. Most agencies rely on commercial software tools for a wide spectrum of functions, including highway and bridge design, construction management, maintenance management, field inspection data collection, and traffic forecasting. When a mix of tools from different vendors is used, when an agency chooses to switch to a new tool in the same functional area, or when an agencyâs partners (e.g., contractors, other juris- dictions) attempt to share data created with disparate tools, they face a host of data compatibility and consistency issues. Lack of interoperability across systems means that agen- cies must expend considerable resources to build custom inter- faces, or live with duplicative data creation processesâwith associated inefficiencies and loss of data consistency and qual- ity. In many instances, the result is that information that could be valuable for decision-making is simply not available. Com- monly agreed-upon data standards would yield substantial benefits, including improved efficiency, better information quality, and increased flexibility to make use of emerging soft- ware that best addresses particular business requirements. XML: An Enabling Technology for Data Interoperability In recent years, XML (an acronym for eXtensible Markup Language) has become a near-universally accepted and S E C T I O N 1 Introduction
supported mechanism for data exchange across platforms and applications. XML data structures, known as schemas, provide a mechanism to develop and adopt common for- mats for universal data exchange, thereby, allowing sepa- rate information systems to communicate. XML provides a formal, self-documenting structure to share data, inde- pendent of the software that produced it. It also provides a mechanism for long-term archiving of data that might otherwise be difficult to access when host applications are retired. XML schemas have been developed in many industries, including publishing, insurance, education, and electronics. XML is not a silver bullet to the problem of standards development, but it is a maturing technology that promises to improve the flow of information. With XML-based inter- faces between software applications, and between people and those applications, the flow of information can become more efficient and effective. This can lead to improvements in the facility life-cycle processes, and, ultimately, to improvements in the facilities themselves. There currently are several open consortia of private and public sector organizations working to create transportation XML schemas. However, until this project there has been no formal framework within the transportation community to sponsor, develop, and maintain XML schemas; promote schema consistency and acceptance; solicit broader input; and build consensus. For many transportation applications, XML schemas do not yet exist. 1.2 Research Objectives The objectives of NCHRP Project 20-64 were to develop broadly accepted public domain XML schemas for exchange of transportation data and to develop a framework for develop- ment, validation, dissemination, and extension of current and future schemas. The ultimate goal of this effort is TransXMLâ a family of XML schemas for transportation applications, and a recommended institutional structure and process for implementing and sustaining its use. This project focused on four business areas within transportation (1) Roadway Survey/Design, (2) Transportation Construction/Materials, (3) Highway Bridge Structures, and (4) Transportation Safety. However, it is envisioned that TransXML will ultimately encompass a broader set of schemas for other transporta- tion business areas. The research objectives recognized the importance of estab- lishing an umbrella framework for future transportation XML schema development, in order to avoid overlapping and inconsistent efforts. They also recognized that trans- portation data standards are only effective if they are widely adopted. The technical development of TransXML is not suf- ficient to achieve the desired result of better data exchange within and across transportation business areas. An institu- tional framework or âroadmapâ is also necessary to encour- age the continued development and adoption of TransXML. The institutional structure and processes for TransXML are essential for achieving TransXMLâs long-term goal of easy transportation data exchange. 1.3 Research Approach This research was undertaken in two major phases. In Phase I, the project team documented relevant existing XML efforts; identified opportunities in surface transporta- tion where use of XML could yield significant benefits; iden- tified specific gaps and opportunities in the four identified key business areas; and mapped out a plan for development of schemas to fill the highest priority gaps. Phase I also established a website for information dissemination and for collaborative schema development among TransXML stake- holders, and identified potential lead organizations for stewardship of TransXML. In Phase II, the project team designed and developed a set of XML schemas and associated sample applications. Phase II also developed recommendations for institutional structures, processes, and funding mechanisms for contin- ued schema development and for sustaining the TransXML effort. The research work program had the following tasks: ⢠Task 1. Develop a Project WebsiteâEstablish initial website for the TransXML project to post goals, plans, status, work in progress, final deliverables, names of par- ticipants and partners, outcomes, and other pertinent information. ⢠Task 2. Identify Surface Transportation Business Areas for TransXMLâProvide a high-level view of surface transportation data exchange requirements by identifying which are presently being addressed using XML schema, and which would benefit from development of new XML schemas. ⢠Task 3. Review Existing XML SchemasâDocument the status of existing XML efforts in transportation, and iden- tify specific public domain schemas that can be incorpo- rated into TransXML. ⢠Task 4. Identify Potential Organizations for TransXML StewardshipâIdentify candidate organizations and agen- cies that could take on long-term responsibility for TransXML, and document the relative advantages and dis- advantages of each. ⢠Task 5. Business Area Gap AssessmentâAssess the four business areas identified for initial investigation (see Table 1) 6
to identify and prioritize where XML schemas would be beneficial, and where activities are already supported by existing XML schemas. ⢠Task 6. Schema Development PlanâBased on the prior- ities established in Task 5, develop a plan for full develop- ment of the initial set of TransXML schemas that can be successfully accomplished within the confines of the budget and schedule. ⢠Task 7. Develop Moderated Web-Based Collaboration ToolâDevelop a website which will serve as a forum for collaboration across a wide spectrum of stakeholders on the development of TransXML schemas. ⢠Task 8. Phase 1 Interim ReportâPrepare a report docu- menting work completed in Tasks 1 through 7. ⢠Task 9. Develop Business Area XML SchemasâDesign and develop XML Schemas using an open process that encourages wide participation by stakeholders. ⢠Task 10. Develop Web-Based Validation Softwareâ Provide web-based software to check submitted TransXML schemas for compliance with TransXML schema require- ments (and W3C specifications). ⢠Task 11. Software Documentation, Source Code, and Sample DataâDevelop sample software and datasets demonstrating application of the new TransXML schemas. ⢠Task 12. Recommend Implementation Frameworkâ Recommend a framework for supporting continued schema development and improvement. ⢠Task 13. Recommend TransXML Stewardship Modelâ Develop recommendations and an implementation plan for future funding, management, and maintenance of Trans- XML to encourage its sustained development and use. ⢠Task 14. Final ReportâPrepare final report documenting the results of Tasks 1 through 13, and a companion CD- ROM including the text of this report, the TransXML schemas and documentation, the Tasks 10 and 11 software programs and data, source materials for the Tasks 1 and 7 websites, and an archive of all postings made to the col- laboration tool. ⢠Task 15. AASHTO IS PresentationâDevelop and deliver a summary presentation for the TransXML project at a meeting of the AASHTO Administrative Subcommittee on Information Systems. 1.4 Contents of Report This report summarizes the results of Tasks 1 through 13. It is organized in the following sections: ⢠Section 1 list sources cited in this report. ⢠Section 2 provides a high-level view of surface transporta- tion data exchange requirements, providing a context for formulation of long-term goals for TransXML. ⢠Section 3 reviews prior XML schema and data standards relevant to the four focus areas of roadway survey/design, transportation construction/materials, highway bridge structures, and transportation safety. It identifies prior schema which could be incorporated into TransXML. ⢠Section 4 identifies and prioritizes gaps between key busi- ness areas where XML schema would be beneficial, and business areas already supported by prior XML schemas. ⢠Section 5 describes the TransXML schema development process and work products. 7 Highway Bridge Structures Transportation Safety Roadway Survey/Design Transportation Construction/ Materials ⢠Bridge Analysis and Design ⢠Bridge Load Rating ⢠Bridge Construction ⢠Bridge Inspection ⢠Bridge Management ⢠Bridge Operations ⢠Bridge Maintenance ⢠Crash Reports ⢠Crash Location ⢠Roadway Inventory ⢠Citations ⢠Driver Information ⢠Vehicle Information ⢠Emergency Medical Info ⢠Federal Motor Carriers Info ⢠Crash Analysis ⢠Work Zone Safety ⢠Design Surveys ⢠Parcel/Boundary Surveys ⢠Geometric Design ⢠Pavement Design ⢠Right-of-Way ⢠Construction/ Stake-out ⢠Survey Feature Codes ⢠Cross Section ⢠Pay Item Quantities ⢠Estimates ⢠Proposals ⢠Letting and Award ⢠Construction Management ⢠Materials Table 1. Business areas for TransXML.
⢠Section 6 discusses future stewardship of TransXML. It examines options and presents an implementation plan. ⢠Section 7 lists sources cited in this report. ⢠Appendix A includes detailed information on existing XML standards that were evaluated for relevance to TransXML. These reviews were current as of October 2004. ⢠Appendix B is the summary report documenting the investigation of the use of the Geographic Markup Lan- guage (GML) as the basis for TransXML. ⢠Appendices C and D present the UML models developed in this project, which represent the results of the design phase of XML schema development. ⢠Appendix E documents the XML schema and applications developed for this project that were delivered to NCHRP in electronic form. ⢠Appendix F contains applications and source code. ⢠Appendix G provides feedback on schemas and UML models. 8