Research Project:

Addressing Integration Issues and Developing a Protocol for Integration of Global Positioning Systems Data With Linear Referenced Data in an Asset Management System

ArcView screen showing the centerline determination

Final Report

PDF version 1.1 MB
HTML version 482k

Principal Investigator

Shauna Hallmark
Iowa State University
(515) 294-5249
shallmar@iastate.edu

External Project Contact

Bill Schumann
Iowa Department of Transportation
800 Lincoln Way, Ames, Iowa 50010
(515) 233-7770

Project Objective

To develop a case study that identifies and addresses issues to help state and local agencies integrate global-positioning systems (GPS) based data into linearly referenced asset management databases.

Project Abstract

Global positioning systems (GPS) offer a cost-effective and efficient method to input and update transportation data. The spatial location of objects provided by GPS is easily integrated into geographic information systems (GIS). The storage, manipulation, and analysis of spatial data are also relatively simple in a GIS. However, many data storage and reporting methods at transportation agencies rely on linear referencing methods (LRMs); consequently, GPS data must be able to link with linear referencing. Unfortunately, the two systems are fundamentally incompatible in the way data are collected, integrated, and manipulated.

In order for the spatial data collected using GPS to be integrated into a linear referencing system or shared among LRMs, a number of issues need to be addressed. This report documents and evaluates several of those issues and offers recommendations. In order to evaluate the issues associated with integrating GPS data with a LRM, a pilot study was created. To perform the pilot study, point features, a linear datum, and a spatial representation of a LRM were created for six test roadway segments that were located within the boundaries of the pilot study conducted by the Iowa Department of Transportation linear referencing system project team.

Various issues in integrating point features with a LRM or between LRMs are discussed and recommendations provided. The accuracy of the GPS is discussed, including issues such as point features mapping to the wrong segment. Another topic is the loss of spatial information that occurs when a three-dimensional or two-dimensional spatial point feature is converted to a one-dimensional representation on a LRM. Recommendations such as storing point features as spatial objects if necessary or preserving information such as coordinates and elevation are suggested. The lack of spatial accuracy characteristic of most cartography, on which LRM are often based, is another topic discussed. The associated issues include linear and horizontal offset error. The final topic discussed is some of the issues in transferring point feature data between LRMs.

Task Descriptions

Literature review.
Develop a standardized method to use GPS data for asset management.
Develop a methodology to integrate GPS data collection with LRS data including development of map-matching algorithms suited to locating data within existing GIS databases and especially for referencing GPS data to LRS data.
Final report to present findings and recommendations for technology transfer.

Milestones, Dates

Project start: July 2000
Task 1: August 2000
Task 2: February 2001
Task 3: February 2001
Task 4: May 2001
Project end: May 2001

Student Involvement (e.g., Thesis, Assistantships, Paid Employment)

N/A

Relationship to Other Projects

The project is focused on "demand-side" issues in that they will identify what is needed to implement the GPS protocol. "Hands-on" activities will provide a practical means of surveying the hidden issues that will emerge relative to implementing GPS based asset management technologies.

Technology Transfer Activities

Distribution of the final report and developed algorithms to interested parties as well as presentation of results at professional conferences.

Potential Benefits of the Project

The project will be valuable to transportation agencies that need to integrate legacy databases and newly collected GPS data into asset management systems. More specifically, it will yield the following:

Recommendations on the level of accuracy required for data collection related to transportation data using GPS.
Methodologies used by other agencies to collect data using GPS.
A general review of linear referencing systems including techniques employed and related problems such as transferring LRS data between systems.
Use of GPS data in a GIS.
An overview of the LRS system now being developed by the Iowa Department of Transportation.

Budget

$28,000

TRB Keywords

global positioning system, integration, linear referenced data, asset management