improving iowa’s road centerline databases
DESCRIPTION
Improving Iowa’s Road Centerline Databases. Bill Schuman, GIS Coordinator Karen Carroll, Transportation Data. Session Outline. Linear Referencing System What is a linear referencing system? LRS Core Components LRS Maintenance Application - PowerPoint PPT PresentationTRANSCRIPT
Improving Iowa’s Road Centerline
Databases
Bill Schuman, GIS Coordinator
Karen Carroll, Transportation Data
Session Outline
• Linear Referencing System– What is a linear referencing system?– LRS Core Components– LRS Maintenance Application
• Geographic Information Information System (GIMS) Redesign
• Decision Support Environment– What is a Decision Support Environment?– Oklahoma DOT GRIP Demonstration
Session Outline
• Linear Referencing System– What is a linear referencing system?– LRS Core Components– LRS Maintenance Application
• Geographic Information Information System (GIMS) Redesign
• Decision Support Environment– What is a Decision Support Environment?– Oklahoma DOT GRIP Demonstration
Linear GIS Data Models Special Problems in Linear GIS
CartographicRepresentation
Business Data
Linear GIS Data Models Different Approaches
• Fixed length segments– All segments the same length– Must summarize data & very redundant
• Variable length segments– Segment determined by unique sections– Some summarization & redundancy
• No segments / dynamic segmentation– Minimizes redundancy– More database tables
0.1 mi
Linear GIS Data Models Fixed Segment Length
CartographicRepresentation
Business Data
0.1 mi
road_info
City ACity B
city_info
road_namepavement_typeno_of_vehiclesjurisdiction
Linear GIS Data Models Variable Segment Length
road_nameMain Street
road_namepavement_type
AsphaltConcrete
road_namepavement_typeno_of_vehicles
5002500
road_namepavement_typeno_of_vehiclesjurisdictionguard_railstructure
structure
road_namepavement_typeno_of_vehiclesjurisdictionguard_rail
guard_rail
Linear GIS Data Models Dynamic Segmentation Analysis
Pavement Type
Speed Limit
AADT Values
Friction
35 45 55
34 30 32
Asphalt Concrete
30000 22000
Asphalt
0
0
0
0
2.1
2.5
0.5 2.3 4.8
4.1 5.2
5.80.2
Linear Query Results where: Speed => 45
AADT < 25000 Pavement = Asphalt Friction =< 30
5.85.22.5 4.1
What does Iowa need to do?
Do we need
more accuracy?
How do we develop
a linear network?
What do our
customers need?
What linear datamodel shouldwe use?
How do we keep
our data current?
Meeting the NeedsIowa DOT’s Approach to Problem
• Created a team to make recommendations to DOT management
• Researched state of practice– Looked at accepted processes/systems– Looked at new processes/systems
• Inventoried current linear location methods used in Iowa
• Investigated linear location needs of Iowa’s data users
• General recommendation: Develop a Linear Reference System (LRS)
LRS Core ComponentsFundamental Definitions
• LRS - Linear Referencing System– A set of procedures and methods for specifying a
location as a distance, or offset, along a linear feature, from a point with known location.
– A LRS can relate a linear location (1D) to a spatial (2D) location through a centerline representation of the roadway.
• LRM - Linear Referencing Method– Different methods of measuring locations (i.e.
milepost, literal descriptions, stations, address ranges, etc.).
– A LRM is part of the LRS.
LRS Core Components The Team’s Recommendations
• Need to improve spatial representation of the road centerlines
• Use NCHRP (20-27) project model
• Need ability to integrate variety of data– Mile post referenced data (US 30 @ 135.23)– Coordinate referenced data (Lat, Long, I35)– Literal description data (2.51 mi past 1st St)– Road address data (247 E. Main St)
• Establish maintenance processes and partnerships
LRS Core Components Simplified Visual
CoordinateRoute
ReferencePost
GIMSSegmental
Milepoint StationingLiteral
Description
BaseRecordCrash PMIS Inventory Project
DataProgram
LRS Core Components Simplified Visual
LRS Components
CoordinateRoute
ReferencePost
GIMSSegmental
Milepoint StationingLiteral
Description
BaseRecordCrash PMIS Inventory Project
DataProgram
CenterlineRepresentation 2
CenterlineRepresentation 3
CenterlineRepresentation 1
AddressRange
LRS Core Components Statewide Data Collection Effort
• Centerline collection complete for all Interstate, US, and State roads
• Eight counties collected
• Collected from best image source available
LRS Core Components Local Roads in LRS
• Four counties
• All primary roads completed by end of FY03
• 28E Agreement with City of Des Moines– Agree to maintain
street centerlines– $50,000 to LRS
LRS Core Components Comparison of Centerlines
LRS Core Components Feature Association
LRSx Conflation Object
LRSx Conflation Object
CartographicRepresentation
Datum
Network
%AS
%AS
%AS %AS
%AS %AS %AS%AS
LRS Core Components Maintenance Application
• Maintains the data in the LRS database
• Constructed on commercially available products– GeoMedia (Professional & Transaction Mgr)– Oracle (Core, Spatial, & Workspace Mgr)– Location Data Manager Extensions (LDMx)
• Three-tier architecture
• Contains a change propagation engine, quality control checker, and temporal data management
LRS Core Components Maintenance Application
Architecture
LRS Core Components Maintenance Application
Architecture
LRS Core Components Maintenance Application
Architecture
LRS Core Components Maintenance Application-Change
Tracking
LRS Core Components Maintenance Application-Metadata
LRS Core Components Maintenance Application-
Conflation
LRS Core Components Maintenance Application-
Conflation
LRS Core Components Maintenance Application-
Conflation
LRS Core Components Maintenance Application-Quality
Control
LRS Core Components Maintenance Application-Routes
LRS Core Components Maintenance Application-Temporal
LRS Core Components Maintenance Application-Temporal
LRS Core Components Maintenance Application-Temporal
LRS Core ComponentsConclusions
• LRS Purposes– Ability to integrate plethora of data– Remain scalable for future needs– Provide a comprehensive transportation
GIS
• LRS Maintenance Application– Make it easy to maintain a fairly complex
database– Provide good metadata and history for the
road network– Always ensures a quality database
Session Outline
• Linear Referencing System– What is a linear referencing system?– LRS Core Components– LRS Maintenance Application
• Geographic Information Information System (GIMS) Redesign
• Decision Support Environment– What is a Decision Support Environment?– Oklahoma DOT GRIP Demonstration
Session Outline
• Linear Referencing System– What is a linear referencing system?– LRS Core Components– LRS Maintenance Application
• Geographic Information Information System (GIMS) Redesign
• Decision Support Environment– What is a Decision Support Environment?– Oklahoma DOT GRIP Demonstration
L
inear B
usin
ess Data
Decision Support Environment
System Architecture for Integrating Data
Staging Process
Crash Records
PMIS
Bridge
GIMS
General DecisionSupport
CTAMS
PMIS
Sufficiency
Web CTAMS
Specific AnalysisSystems
Geo
Data L
ibrary
LRS Maintainer
Derived Data Valuesfrom Integrated Data
Derived Data Valuesfrom Integrated Data
LRS
GIS Maintainer
GIS
Decision Support Environment
Iowa DOT CTAMS Project
Decision Support Environment
Iowa DOT CTAMS Project
Decision Support Environment
Oklahoma DOT GRIP Project
Decision Support Environment
Oklahoma DOT GRIP Project
Decision Support Environment
Iowa DOT ERMS/GIS Integration Project
Decision Support Environment
Oklahoma DOT GRIP Project
Decision Support Environment
Oklahoma DOT GRIP Project
Session Outline
• Linear Referencing System– What is a linear referencing system?– LRS Core Components– LRS Maintenance Application
• Geographic Information Information System (GIMS) Redesign
• Decision Support Environment– What is a Decision Support Environment?– Oklahoma DOT GRIP Demonstration
Presentation Wrap-up Benefits of the LRS - Opportunities for
Savings
• Provides a centralized data source for most road transportation information systems
• Minimizes redundancy• City Government (Utilities, Engineering)• County Government (Engineering, Assessor)• State Government (DOT, Emergency Mgmt)• Federal Government (Census, FHWA)
• Expend resources to provide more extensive and accurate data, rather than similar copies
• Benefits homeland security and emergency management
• Share maintenance effort
Additional Information
• Presentation available at:
www.iowadotmaps.com
Click on the “Links” pulldown
Pens have web page printed on side
• New 2004 Transportation Map!– Just released today!
Questions