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RHD Operational Procedure – Planning and Maintenance Wing
 
HDM - Database Division
 
OP/HDM/2.1 - Management of RHD Digital Maps
 
Purpose and Scope :

The purpose of this procedure is to describe how RHD digital map data should be managed to provide secure, long-term storage and high quality data, easily accessible to its users in a timely manner.
 
Definitions :

GIS: Geographical Information System is defined as an information system used to input, store, retrieve, manipulate, analyse and output geographically referenced data or geo-spatial data, in order to support decision making for planning and management of land use, natural resources, environment, transportation, urban facilities, and other administrative records.

RMMS: Road Maintenance and Management System, is a database which contains the available information for the RHD Road Network.
 
Responsibility :

SE–HDM Circle: overall responsible for GIS management issues and policy strategies, and co-ordinate with RHD decision-makers.

Executive Engineer-Database Division: As Database manager: overall responsible for supervision of GIS development, GIS budgeting, spatial data collection related to GIS, reports and document preparation. Responsible for Co-ordinating GIS development with RMMS database development.
 
Method :

The management of RHD digital maps requires good organisation of GIS digital data. This procedures includes data collection, management and data organisation, database construction, data quality and the GIS data archives in RHD.

4.1 GIS DATA CAPTURE / DATA COLLECTION

GIS data can be collected using the following methods and sources:

· Digitising / scanning from hardcopy maps

· Field survey using GPS receiver

· Satellite Imageries by classifying colour bands and vectoring

· Collection of road information of (RHD is the custodian for National, Regional and District roads and LGED for rural roads).

· Collection of Digital map data from other organisations such as LGED

Generally GIS data can be collected from the above sources and methods. RHD’s GIS data capture has been mainly done by digitising road or road related feature from hard copy maps or by field survey using GPS. Data collection from other agencies (e.g. LGED) is also a major source of RHD GIS data. Data collection is a continuous process throughout the whole life cycle of the GIS system. GPS road alignment survey methodology and procedures are given in GPS survey manual (see references).

The current RHD GIS, has been built with data, mostly collected by GPS field survey and available information from RHD offices. This was combined with digital thana-base maps procured from LGED.

It is important, for every new road or bridge development project, or inclusion of roads into RHD road network, the road features along with other tabular information should be collected and entered into the GIS system. EE Database will coordinate the needed surveys with EE Data Collection.

Exchange and coordination of data collected is important, particularly data collection from RHD field offices. In this respect EE Data Collection Division should always contact with RHD officials (or through SE HDM) to the respective RHD offices for necessity actions. Under the supervision and the co-ordination of EE Data Collection Division, SDE/AE will conduct the data collection.

4.2 DATA VERIFICATION AND QUALITY ASSURANCE

· Data verification

· Quality and data standard

All data sources and spatial data entry methods will result in some errors in the information inputted into GIS. The type, severity, implications of these errors (often inherent in GIS) will determine the quality of the GIS spatial data. These errors must be recognised and properly dealt with. It is virtually impossible to eliminate spatial data errors altogether, but GIS users can reduce and manage errors by good working practices, thus improving the quality.

Verifying the accuracy of spatial data is essential for RHD Digital data management. Tabular data also needs to be verified to ensure the data quality in the GIS database. Data quality measure should include positional accuracy, completeness, correctness and integrity of spatial data.

4.3 DATA PROCESSING AND DATABASE DEVELOPMENT

· Data processing and editing

· Standard Shape file/coverage processing

· Key feature attributes

· Data-Documentation

The collected data needs to be processed and made usable for the GIS system. Data processing and editing is fully implemented using GIS software. All the RHD road and road related features should be processed in “ArcInfo Coverage” or equivalent Shapefiles. All the road or related features should be identified correctly and given an identification number such as a combination of Road number, Road link number, Start and End location and the link length should be defined correctly.

Any amendment of existing feature data sets or newly built datasets, should be documented. This will ensure all GIS users can use these data sets. This standard data documentation or meta-data should be circulated among its users.

4.4 INTEGRATION OF RMMS DATABASE

Access and linking to the RMMS database is a vital function of the RHD GIS system. The RHD GIS system is able to access the RMMS database, which is held in RHD server. All GIS maps should be joined with RMMS tables and table objects virtually and dynamically. This means changes made to the database tables, are reflected in changed map content (data should not be copied from RMMS to tables located within a GIS map as this will not stay up-to-date). Road link number in GIS road database with RMMS database tables should be used for this integration.

4.5 AUTOMATED CARTOGRAPHY

4.5.1 ROUTINE MAP PRODUCTION

All wings/offices within RHD require up to date road maps. This requires a well-managed centralised Road GIS has been established. This facility requires a master digital road network upon which other relevant information can be attributed such as road condition, road roughness and road traffic.

Generally, the RHD GIS unit produces two categories of road maps. These two categories are RHD Road network maps and RHD thematic road maps which provide specific relevant information.

RHD Road Map
- Road Number, Link Number, Start and End of locations are attributed.

RHD Thematic Map
- Different aspects, such as road condition, road roughness and road traffic are highlighted using colour symbols are utilised on road links or road sections to visualise the above data.
- One of the major objectives of GIS mapping is to produce a series of thematic maps based on the HDM output results for Road maintenance, such as for project priority rating, based on impact analysis in terms of resource constraints, to maximise the cost effectiveness of maintenance rehabilitation plans for different budget levels.

4.5.2 ADHOC MAPPINGS

Apart from routine GIS map production the GIS department receives other requests for maps. These mapping requests may be received from ongoing RHD roads and bridge projects or other Government departments. No mapping requirements are received from private or non-government organisations at present (see OP/HDM/2.4).

4.6 DIGITAL MAP DATA ARCHIVES

All the processed and final GIS data sets and Maps are stored on the RHD server, where all users can access them through windows network. Figure 2 shows the layout for GIS data and map location on the server. This is supported by a Data Dictionary and Map catalogue maintained by the Database division.

When making amendment or changes to either the data or processed maps, the EE Database or officer in-charge should also make the necessary changes in the Data Dictionary and Map Catalogue. This aims to ensure all users work on the same set of data and maps.

4.6.1 GIS MAP AND DATA DISSEMINATION

GIS maps are disseminated in the following ways:

· WWW: GIS Websites (RHD GIS website is now under development);

· Digital Map data map (copied in a reliable magnetic medium); and

· Hard copy maps printed

GIS data dissemination depends on the policy adopted by the department considering what level of maps or data and how other user (external user) could access.
 
References :

Development of a Geographic Information System (GIS) (June 1995, IDC project).

National Road Sector GIS, Full Scale Implementation of GIS, a Proposal to DFID (July 1996, IDC project).

GPS Concept and Methodology (June 2002, IDC3 project).

GIS Database User Manual - to be developed.
 
Procedure Flowchart :

The procedure flowchart for this procedure is detailed below -
 


 


 

 

For duties associated with each grade of personnel see

 

Updated on : 1/12/2003

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