LandXML 2.0: New Update to Data Exchange Standard

History of LandXML for 3D Data Exchange

The LandXML Data Exchange project was initiated in 1999, driven by needs of various U.S. Departments of Transportation who had experienced data exchange problems due to proprietary formats. Autodesk was a main sponsor of the LandXML 1.0 effort which led, among other benefits, to improved data exchange between projects designed in Bentley Microstation ® and Autocad®-based solutions. Because LandXML applies to surface TINs, to horizontal and vertical alignments and to cross section data, LandXML files can fully define 3D road and site designs. Widespread adoption occurred worldwide, almost immediately. U.S. DOT’s began to exchange data with surveyors, civil engineers and contractors by LandXML. This format has become a standard for engineering design data transfer.

By November, 2007 LandXML.org had grown to 673 representatives from 582 member companies and government agencies, representing 41 countries. Carlson Software, a strong believer in open data exchange, was an early adopter and promoter, adding the term “XML” to several of its annual releases. In January, 2014, Carlson Software became the principle sponsor for LandXML.org.

Mission of LandXML.org
There are 4 primary missions of LandXML.org:

(1) To transfer engineering design data between producers and consumers.
(2) To provide a data format suitable for long-term data archival.
(3) To provide a standard format for electronic design and survey submission.
(4) To support intelligent construction data flow from office to field and back to office.

LandXML as Worldwide Standard
Based on the WC3 XML Schema recommendation of May 2, 2001, LandXML 1.0 was ratified by LandXML.org on July 17, 2002. LandXML 1.1 was ratified on July 21, 2006 and LandXML 1.2 followed on August 15, 2008. Each of these versions came with a Developer’s Kit with documentation. LandXML is now supported by over 60 software applications including Autodesk, Bentley, Carlson, Eagle Point, MicroSurvey, NovaPoint, Leica Geosystems, Trimble Navigation, Topcon, the U.S. FHWA and many more. LandXML is the design data schema for the AASHTO TransXML standards. Internationally, LandXML is the survey data standard used in New Zealand’s LandonLine system and for Australia’s ePlan online cadastral survey system. Countries as wide ranging as Sweden, Finland and Slovenia have adopted LandXML to define their roadway systems for construction.

Applications to 3D Machine Control
Roads designed in Scandinavia, particularly in Norway, Sweden and Finland, are often fully defined by alignment files in LandXML format, many times including all surfaces to be graded. Each edge-of-pavement, shoulder, ditch and other “string” alignment defining a surface is identified as both a horizontal and vertical alignment in the LandXML file.

Furthermore, each distinct surface is separately identified. In this way, one LandXML file can contain the entire road design for purposes of survey stakeout and machine control. In the example below, which includes only the beginning portion of an entire road project, the Novapoint software provides an alignment name and information on the coding.

-    <LandXMLxmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.landxml.org/schema/LandXML-1.0" version="1.0" time="05:33:54" date="2011-04-06" xsi:schemaLocation="http://www.landxml.org/schema/LandXML-1.0 http://www.landxml.org/schema/LandXML-1.0/LandXML-1.0.xsd">
-    <Units>
<MetricdirectionUnit="radians" angularUnit="radians" pressureUnit="mmHG" temperatureUnit="celsius" volumeUnit="cubicMeter" linearUnit="meter" areaUnit="squareMeter"/>
</Units>
-    <Applicationversion="17.20" manufacturerURL="www.novapoint.com" manufacturer="Vianova Systems AS" name="Novapoint">
    <AuthorcreatedBy="setp13203"/>
</Application>
-  <Projectname="C:\_WSPData\INS\Db\DB_KFU_NS15&NS13\VMOD\316">
   -  <Featurecode="IM_codings"><Propertyvalue="VV RITHANDBOK 2.01" label="terrainCoding"/><Propertyvalue="VV RITHANDBOK 2.01" label="surfaceCoding"/><Propertyvalue="VV RITHANDBOK 2.01" label="infraCoding1"/>
</Feature>
</Project>
-    <Alignmentsname="316">
-    <Alignmentname="316" length="971.597307" staStart="0.000000">
-    <CoordGeom>
-    <Linelength="27.309619" staStart="0.000000">
<Start>6581158.362094 151616.365550</Start>
<End>6581180.578173 151632.248280</End>
</Line>
-    <Spirallength="35.731361" staStart="27.309619" rot="ccw" spiType="clothoid" radiusEnd="600.000000" radiusStart="INF" constant="146.420">
<Start>6581180.578173 151632.248280</Start>
<PI>6581199.957122 151646.102688</PI>
<End>6581209.848914 151652.738602</End>
Etc.

LandXML 2.0 Updates
LandXML 2.0 is scheduled for release in December, 2014. Its goal is to provide even more flexible support for sharing and transferring design files from office to field surveying and machine control applications. Surfaces can be defined as TIN files, triangulated networks, as grid files, as cross sections, and as “strings” of alignments. These 4 distinct methods of describing surfaces are all adequately handled by current LandXML schemas and formats. LandXML2, however, will include surface definitions based on road templates (in effect, a single cross section) acted upon by superelevation, template ID “rules” in the form of grade tables and horizontal and vertical alignment files for the “hinge point” where the template attaches. Points for grade breaks can be established by reference to template ID points and subgrade and surface pivot points, such as for superelevation, can be defined parametrically as in “EP+4”. For example, even if the EP (edge-of-pavement) position expands for a passing lane, a superelevation break point can be placed at the position “EP+4”. Templates can also transition to other template files in the new LandXML 2.0 format.

Templates, sometimes referred to as “typical sections”, have been a file format that has mostly defied efforts at data exchange between different design programs. By having a template definition in LandXML, which will respond dynamically to station-referenced superelevation and lane width and slope files, templates can potentially simplify data exchange for the majority of new road projects such as subdivision roads, access roads, bypasses, ramps and entrances and other straightforward, rule-following designs. Subgrade surfaces will be embedded within the template design with distinct rules for segment slopes and dimensions including dynamic intersections with upper surfaces. Extremely complex and variable road designs may still benefit from full alignment file (as practiced in Scandinavia) and TIN file LandXML descriptions.

Two additional goals of LandXML 2.0 will be to establish a form of storage that prevents alteration and enables use as a “professionally sealed” record of the project, and secondly to include a viewer that can present labeled cross sections based on TIN or alignment files using any referenced centerline in the LandXML file.

LandXML 2.0 will continue to use current W3C XML standards. The LandXML 2.0 development team, which includes original author Nathan Crews, will engage the OGC and TransXML to improve adjacent standards interoperability. In particular, 3D road model improvements will be made based on worldwide input in addition to template additions. There will be many improvements in other areas related to road construction, including support of sanitary sewer pipes, structures and networks as well as storm sewer culverts, ponds and combined closed/open storm sewer networks.

Conclusion
LandXML 2.0 will reinforce and extend LandXML as the standard design data exchange format for surveyors and for applications in machine control for heavy/highway construction. The Carlson SurvCE and SurvPC programs offer complete data exchange and stakeout features based on all forms of LandXML surface definitions and will adapt, in advance, to the LandXML 2.0 additional template and pipe formats. The Machine Control solutions of Trimble, Topcon, Leica and Carlson, including also Caterpillar, are all expected to continue to support the importing of surface files in LandXML format. The world survey and construction market has adopted LandXML as the de facto data exchange standard.

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