VEHICLE INTELLIGENCE & TRANSPORTATION ANALYSIS LABORATORY  University of California, Santa Barbara

Research

The error in this case is not in the GPS coordinate — with differential correction commonplace, that is accurate to a couple of metres.  The problem is positional disagreement in the reference databases on which the coordinates are plotted.  The navigation system in the reporting vehicle snaps the coordinate to one ramp.  At the 911 center (which employs a different database) the same coordinate snaps to another ramp.

Much of ITS hinges on communicating the location of a vehicle, facility or event.  The US DOT ITS Program states: “One of the highest priority enabling standards identified in the ITS America survey is that of Location Referencing.” To make location referencing unambiguous and error-free, two standards strategies must be pursued simultaneously: coordinate standardization (addressed by the ITS Datum) and messaging standards (addressed by the Location Reference Messaging Specification or LRMS).

These two national efforts constitute the core of the research agenda at VITAL.  Our work takes place in the lab, conceptualizing and critiquing, and in the field, surveying points, testing emerging technologies, and talking to highway workers in hard hats.
 

Current Research Projects	To enable field experiments, VITAL's first task (January–July 1997) was to build an experimental infrastructure for ITS testing, consisting of a mobile observation vehicle in communication with a fixed server, and a set of street databases.  The basic infrastructure is now complete; it will be customized as required to support specific experiments. We have initiated work on Positional Error.  This will be ongoing alongside other testing, because positional error issues are the centerpiece of our work.  Most recently the positional error research has culminated in solutions  In August–October 1997 we tested the Cross Streets Profile (XSP), part of the LRMS.  The Profile was modified following our recommendations, and we re-evaluated its performance in October 1997–March 1998. In 1998-99 we evaluated the Linear Referencing Profile (LRP).  That report is now available, and many of the findings will be of great value to public agencies wrestling with location referencing problems and map database planning. We have begun work on conceptual development and testing of a local prototype of the ITS Datum.  More than 3000 points have been established around the Santa Barbara urban area, and our rubber-streeting algorithm can now demonstrate the effect of geometric correction using the Datum.  We are working with other agencies (NSDI and NCHRP) who are also proposing national datums, to share ideas and to minimize duplication.	. Infrastructure Positional Error XS Profile LR Profile ITS Datum Technical Reports
Reports	Check here for Technical Papers and Reports from current VITAL research, and earlier NCGIA research in transportation.

Update 1999-05-21