All Roads Do Not End at the State Line: Methodologies for Enabling Geodata Sharing Across Boundaries

Transcription

1 All Roads Do Not End at the State Line: Methodologies for Enabling Geodata Sharing Across Boundaries presented to 22 nd Geospatial Information Systems for Transportation Symposium presented by Julie Chizmas, GIS Analyst Cambridge Systematics, Inc. April 7, 2009 Transportation leadership you can trust.

2 What is the I-95 Corridor Coalition? I-95 CORRIDOR COALITION Beyond Boundaries A partnership of transportation agencies and related organizations, from Maine to Florida and in Canada, working together to accelerate improvements in transportation across multiple jurisdictions and throughout all modes.

3 I-95 Corridor Coalition Stats 21% of Nation s Road Miles 1,919 miles of I-95 40,000 National Highway System miles 35% of nation s vehicle miles traveled (VMT) 5.3 Billion Tons of Freight Shipments Annually 22,000 miles of Class I rail mileage 46 major seaports 103 commercial airports

4 What is ICAT? Integrated Corridor Analysis Tool GIS-based system of transportation networks for the Coalition region Visualize current transportation infrastructure and travel patterns Forecast and display the impacts of future travel volumes in multi-state corridors Designed to help coalition members coordinate multi-state transportation planning, investment and operations.

5 ICAT Components Corridor-wide highway and rail network Topologically connected (flowable) Standardized attributes across all states Links to other federal and state databases Origin-destination (O-D) trip tables County-to-county (sub county) flows Auto and truck trips Current and future years Web-based GIS display system Data Download site

6 ICAT Highway Network Topologically connected ( flowable ) network of major arterial roads in each state Created from highway networks maintained by each Coalition state Includes common attribute template and links to other databases Current hybrid network uses FHWA s National Highway Planning Network (NHPN) as a placeholder for unprocessed state networks

7 Linking Data to Highways Federal Data NHPN FAF HPMS ICAT Highway Link State Data Traffic Data TMC Codes State LRS Inventory data

8 Approach Network based on publicly available state data State planners more comfortable using their own data Easier to integrate with supplemental state data Fewer restrictions on dissemination Automated network maintenance process Attribute data can be easily updated Modular updating of state network geometry

9 Building the ICAT Highway Network Six Step Process: Step 1: Obtain road networks from each Coalition State Step 2: Standardize coordinate system and attributes Step 3: Conflate national data Step 4: QA/QC national data, additional segments Step 5: Extract ICAT segments from state road networks Step 6: Stitch ICAT segments together at state borders Automated processes to facilitate spatial and attribute updates

10 Step 1: Obtaining road networks Contact State DOTs Initial request = letter describing project, purpose, data requirements Follow-up with direct contact Details about network Age, level of coverage, topology, linearly referenced Attribute availability Ensure use permissions for datasets not obtained through public website Get the network and attributes Shapefiles, geodatabases Attributes attached or as event tables

11 Step 2: Standardize the data Coordinate System All state networks converted to lat/lon coordinates GCS NAD 83 Consistent with national data Familiar to many end users (i.e., modelers) Format Geodatabase with attribute domains

12 Step 2: Standardize the data Attributes Based on HPMS Universe Data Items Identification, Function, Capacity-related 33 State-generated attributes 13 Process-generated attributes Highly dependant on state metadata and/or data dictionaries Field descriptions Coded values Automated process Rules built in Access database Copy Look-up Calculate

13 Step 2: Standardize by Copying Target Field Source Field Process StreetName FULLSTNAME Copy SpeedLimit SPEEDLMT Copy Route_Number RTNO Copy TollRoad IsToll Copy

14 Step 2: Standardize by Looking-Up Target Field Source Field Process F_System FUNCT_CLAS Look-Up FUNCT_ CLAS F_Sys Code F_Sys Description Description Non-Public roads Ex: Class 0 VI & Private 7 Local Rural, Principal Arterial - 1 Interstate 1 Interstate Rural, Principal Arterial - 2 Other 3 Principal Arterial - Other 6 Rural, Minor Arterial 4 Minor Arterial 7 Rural, Major Collector 5 Major Collector 8 Rural, Minor Collector 6 Minor Collector (rural only) 9 Rural, Local 7 Local 11 Urban, Principal Arterial - Interstate 1 Interstate Urban, Other Principal Arterial - Other 12 Freeways/Expressways 2 Freeways and Expressways Urban, Principal Arterial - 14 Other 3 Principal Arterial - Other 16 Urban, Minor Arterial 4 Minor Arterial 17 Urban, Collector 5 Major Collector 19 Urban, Local 7 Local

15 Step 2: Standardize by Calculating Target Field Source Field Process Formula County_Code ROUTE_LRS Calculate Left([ROUTE_LRS], 2) Road_Name Pre_dir, Street_Nam, Street_typ, Suf_Dir Calculate AADT FAADT Calculate CLng([FAADT]) Trim([Pre_dir] + " " + [Street_Nam] + " " + [Street_typ] + " " + [Suf_Dir])

16 Step 3: Conflating National Data NHPN Use State Attributes to create NHPN USLRSKey 17 digit code: State FIPS (2) + State Route ID (10) + Sub-Route (2) + County FIPS (3) Create alternate keys to increase chance of matching StateFIPS + CountyFIPS + Route Type + Route Number Conflate segments where where keys are equal within a user-defined tolerance Generate Distance field in output dataset for QC

17 Step 3: Conflating NHPN

18 Step 3: Conflating TMCs

19 Step 4: QA/QC Manually check that all NHPN links are associated with a state road segment. Poor alignment of NHPN segments NHPN connectors missing from state network Unbuilt NHPN links missing from state network Select additional ICAT segments Non-NHPN arterial segments Freeway interchange ramps connecting ICAT segments Additional segments representing U.S. signed routes

20 Step 5: Extract ICAT Segments ICAT segments are flagged in the state road database using a supplemental field New state ICAT database is created from the flagged segments NHPN links for the state are removed from the hybrid ICAT network and replaced by the new state ICAT database

21 Step 6: Connecting at state borders Create points at borders where ICAT roads meet Automated process to "snap" ends to points

22 Prepare Outputs Automated process publishes datasets using a standard template Create Metadata Post shapefiles and geodatabases to FTP site Web-based data viewer

23 WebCAT Flex Viewer

24 WebCAT Flex Viewer

25 WebCAT Flex Viewer

26 Remaining Issues: Topology Several state networks not connected (not flowable) Solutions: Define GDB tolerance Run Clean process with user defined tolerance

27 Remaining Issues: Data Attributes: Some are not available Some are available but not attached to the road network Some are available, but through a different agency Metadata incomplete or non-existent NHPN is several years old (but currently being updated) Some TMCs require some manual code assignments

28 Remaining Issues: Crossing Borders Border connections not always straight-forward Maintain "exception list" of problem areas so when new datasets are received, they can quickly be identified and resolved Dual Centerline Single Centerline Same road represented in both state networks

29 Ideal State Network Characteristics Topologically connected All Roads database Includes local roads and interchange ramps Road segments split at intersections and gore points Divided roadways represented by separate segments State LRS built on top of All Roads database No need to conflate separate road geometries HPMS segments defined using State LRS Straightforward crosswalk between HPMS attributes and State road inventory attributes

30 Keys to ICAT Success Automated Processes Provide consistency, repeatability Use of domains in GDB accommodate code changes Up-front effort = less maintenance/update effort Documentation Written description of processes used Any "issues" with specific datasets States contacts, GIS websites, data dictionaries/metadata Feedback mechanisms

31 In Closing Acknowledgements State DOTs and GIS Staff I-95 Corridor Coalition: Contact Information: Questions or Comments?