LAYER NAME: State Roads  

CUSTODIAN
Department of Land Information (DLI)

TEXTUAL DESCRIPTION
ABSTRACT
The roads dataset, which complies with WALIS defined specifications has been built in response to increasing demands from both public sector and industry organizations for an intelligent robust road centreline dataset. The roads dataset has been compiled by merging the roads layers of the metropolitan street directory, 1:25000, 1:50000 and 1:100000 digital datasets.

DATA CURRENCY AND STATUS
BEGINNING DATE
01 January 1968

ENDING DATE
Current

PROGRESS
In progress

MAINTENENCE
As required

DATA STORAGE 
STORED DATA FORMAT
Digital DB2 

AVAILABLE FORMAT TYPE
SHAPE, AI COVERAGE

ACCESS CONSTRAINTS
No restrictions

DATA QUALITY
LINEAGE
The roads dataset was compiled from the metropolitan street directory, 1:25000, 1:50000 and 1:100000 digital base data. This information was originally captured photogrammetrically then either scanned or hand digitized and stored in MicroStation design files (DGN) or digitized at source using analytical photogrammetric techniques and translated to DGN format. All DGN files have since been loaded into the Arc/Info environment and roads tagged with road name (Geographic Names Register - GEONOMA ID) via an ArcView application.

POSITIONAL ACCURACY
Horizontal accuracy is dependant on the source scale of the data. Based on standard map accuracy statements (1/4 mm at map scale) the accuracy can range between 6.25m and 25m. Where direct capture has been used the spatial accuracy would be better than the minimum specified.

ATTRIBUTE ACCURACY
With the exception of the road name and the road hierarchy attributes all others have been derived from the feature code used in the CAD environment to differentiate features.
The accuracy of the Road name/suffix/direction information is estimated at better than 95%.
The road hierarchy has been assigned based on the Main Roads State Network Maps (August 1999). Accuracy of the assignment of this attribute is estimated at better than 95%.

LOGICAL CONSISTENCY
Checks for under and overshoots were performed in the MicroStation environment using third party software. In addition edges between map sheets were checked and corrected where possible. Edge match problems may still exist as a result of differing dates of photography and data scale differences. In addition mismatches between zones have not been resolved.
Within the Arc/Info environment a topological consistency check to detect flaws in the spatial data are still being performed.

COMPLETENESS
The roads dataset has been compiled from the best available digital topographic information. Selected towns were revised in 1999 using cadastral information as a backdrop along with consultation with local government authorities where clarification was required. Maintenance of the dataset is ongoing. The spatial completeness of the dataset is being addressed locally as new roads are being added. The metropolitan street directory dataset is consistent with the StreetSmart 2001 Perth Street Directory.

CONTACT INFORMATION
CONTACT ORGANISATION: Department of Land Information (DLI)
CONTACT POSITION: Product Consultant, Geographic Services
POSTAL ADDRESS: PO Box 2222
CITY: Midland
STATE: WA
COUNTRY: Australia
POSTCODE: 6936
TELEPHONE: 08 9273 7373
 

METADATA DATE
7 June 2004