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SUMMARY
TransXML: XML Schemas for
Exchange of Transportation Data
Project Overview
NCHRP Project 20-64 was undertaken to develop TransXML--a family of transportation data
exchange formats using XML--the eXtensible Markup Language. These data exchange formats
are intended to make it easier for transportation agencies to share information within and across
the different stages of the transportation facility life cycle--spanning planning, design, con-
struction, maintenance, and operations. XML is being used in a variety of other industries to
enable data sharing. However, XML in and of itself is not a "silver bullet"; its value depends on
getting agreement on data exchange formats from data owners, data users and software vendors.
TransXML responds to the urgent need for the transportation community to work together on
common data exchange formats. TransXML provides an open, vendor-neutral format for stor-
ing, exchanging, and archiving data. It therefore allows agencies to have more control over their
data, and to get more value out of it over the long haul.
The justification for the TransXML project was to save agencies money. Currently, countless
hours are wasted reentering or recreating information that already exists in electronic form. Data
quality suffers in the process, and additional resources must be invested to ensure that data are
correct with each transfer. Some transportation agencies have already recognized the value of
XML, and are developing their own XML formats or "schemas" to facilitate data exchange across
applications. A collective, broad-based approach to this problem reduces the need for multiple
efforts of this nature. More importantly, it enables and encourages software vendors to build in
standard data import and export features consistent with the agreed-upon formats. This will give
agencies more choices, and will reduce the costs of configuring and implementing new applica-
tions. TransXML also provides a way for agencies to archive their valuable data in a text format
that is human-readable and independent from the software used to create and store it.
Scope and Products
NCHRP Project 20-64 was designed to start development of TransXML by focusing on four
transportation business areas: (1) Survey/Roadway Design, (2) Transportation Construction/
Materials, (3) Highway Bridge Structures, and (4) Transportation Safety. XML Schemas were
developed within each of these areas, along with sample applications that demonstrate how the
schemas can be used. The initial set of TransXML schemas are described in Table ES-1.
For each business area, key stakeholders were identified and input was solicited via e-mail and
via a collaborative website established for the project. Key milestones in the project were as follows:
· Definition of the scope for schemas based on an analysis of data exchange needs and gaps,
· Development of data models for each schema using Unified Modeling Language (UML) class
diagrams,
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Table ES-1. TransXML schemas.
Business Area Schemas
Survey/Roadway Design · Area Features (AF) Schema Allows data from GIS to be
overlaid on design drawings in CAD systems.
· Geometric Roadway Design (GRD) Subset of LandXML
adopted into TransXML allows for sharing of roadway
alignment, cross sections, geometry across members of a design
team, between designer and surveyor, and from design into
machine controlled excavation equipment.
· Design Project (DP) Allows design project pay item data to be
exchanged across design, cost estimation and bid preparation
systems.
Transportation Construction/ · Bid Package (BP) Supports exchange of construction bid
Materials package data between agency systems and contractor bid
preparation software.
· Construction Progress (CP) Supports exchange of information
about partial pay item quantities placed from field data
collection systems to construction management systems.
· Materials Sampling and Testing (MST) Allows exchange of
construction site installed quantities and materials used and
tested information from field data collection systems to
laboratory systems, central construction progress tracking and
contractor payment systems.
· Project Construction Status (PCS) Allows exchange of
construction project status information from construction
management systems to stakeholder information systems (e.g.,
project web sites).
Highway Bridge Structures · Bridge Design and Analysis (BDA) Allows for analysis of the
same structure in multiple structural analysis software packages.
Transportation Safety · Crash Report (CR) Allows exchange and sharing of crash
records data. TransXML adopted the NHTSA/JusticeXML crash
records XML Schema that is based on the Model Minimum
Uniform Crash Criteria (MMUCC).
· Highway Information Safety Analysis (HISA) Allows for
exchange of highway information between inventory systems
and safety analysis software.
All · Linear Referencing (LR) An XML schema for linear
referencing information consistent with ISO 19133 used by the
other TransXML schemas.
· Selection of the Geography Markup Language (GML) to provide a consistent framework for
XML encoding across the new XML schemas to be developed, and
· Development of the XML schemas and sample applications.
Future of TransXML
NCHRP Project 20-64 has provided an initial set of TransXML schemas and has established
an umbrella framework for development of additional schemas. In order to reap the full bene-
fits of this work, there is a need to educate potential users about how to use the schemas, and to
provide technical assistance for agencies and vendors choosing to modify their systems to read
and write data in TransXML format. There is also a need to extend the current set of schemas to
address other data exchange needs both within and outside of the four initial TransXML busi-
ness areas.
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Future efforts should recognize the key lessons learned during the course of this project:
· The TransXML concept of a broad umbrella for a set of interrelated transportation data
exchange formats has the advantage of supporting interoperability of data across different
business processes and life-cycle phases of transportation facilities. However, this umbrella
concept creates challenges in that there are several distinct stakeholder communities within
transportation. This means that extra effort is needed to (a) provide sufficient depth of com-
munication and technical understanding for multiple different stakeholder groups, (b) ensure
technical consistency and coordination across individual schema, and (c) maintain broad
interest and support for the project.
· For TransXML to succeed, there needs to be a substantial and sustained effort to raise aware-
ness of the project. Significant resources must be allocated for communication with stake-
holders--through multiple channels--in order to ensure that the XML schemas are widely
understood and perceived to have clear value.
· Resources must be devoted to coordinate TransXML efforts with related standards efforts since
TransXML touches many areas where schema and standards already exist or are under devel-
opment. This will maximize the potential for synergies and harmonization across efforts.
Based on these lessons learned, a model for future TransXML stewardship was developed,
including a mission statement and a set of recommended functions and roles. Several different
stewardship models were evaluated based on an examination of other XML efforts and consid-
eration of key criteria--including neutrality, stability, agility, technical expertise, marketing capa-
bility, and administrative infrastructure.
Because it is critical to maintain momentum for the TransXML project while a more perma-
nent stewardship arrangement is being established, the project team recommends that AASHTO
take on temporary stewardship for the project for a period of up to 12 months. During this tran-
sition period, AASHTO or a designated contractor would maintain the TransXML website, con-
tinue with a skeletal level of outreach and liaison activities, and initiate one or more pooled fund
projects to demonstrate implementation of selected TransXML schema. During this time, dis-
cussions would be pursued to explore--and ideally obtain commitment for--ongoing sponsor-
ship for the project.
