Improving Iowa’s Road Centerline Databases

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

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


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



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


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-Change

Tracking

LRS Core Components Maintenance Application-Metadata

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 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




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


Iowa DOT CTAMS Project


Oklahoma DOT GRIP Project


Iowa DOT ERMS/GIS Integration Project


Oklahoma DOT GRIP Project

Session Outline




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

Improving Iowa’s Road Centerline Databases

Documents

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