GIS for Water MetersUsing GPS and Map Objects
Tessa M. Allberg
The University of Texas at Dallas
FINAL REPORT
The main purpose of this project is to accomplish four objectives. The first is to create a GIS for the City of Plano Water Meter Inventory. Next, Use GPS to accurately pinpoint the exact meter locations. Then, I plan to maintain and update current water meter inventory based on the data that is generated. Finally, use Map Objects to create a custom application for Field Representatives that service the water meters.
Why is GPS Important to GIS? It is extremely important for this project because
GPS-based data collection can be used to validate and update GIS data. Not only is the
Data quality and reliability is enhanced by positional accuracy, but GPS can be used to update existing GIS features. This is very practical and ensures good data.
The equipment used for the project included the following:
TRIMBLE TSC1 Survey Grade GPS asset surveyor
TRIMBLE Laser Rangefinder
Arc View 3.2 Software
Map Objects 2.0 Software (with Visual Basic 6.0)
Pathfinder Office 2.8 Software
Windows 2000 Workstation
The procedure of the project required steps to ensure that the project was completed in an organized manner. The first step is to gather GPS data by taking GPS locations at each water meter. The next step was to come back to the office to post process GPS data and create shape files. Each shape file that is post processed generates a table based on the attribute information entered out in the field. The next step was to actually generate a water meter database in SDE based on the shape file information. The final step was to input water meter data into Map Objects application using Visual Basic.
Meter Location Accuracy is important because it provides critical information about the location of not just the water meter, but also all water services that are tied to the meter. These include:
Water Mains/Laterals
Sewer Lines
Water Services
Water Valves
Water Hydrants
The City of Plano is made up of Water Meter Districts. There are 70 water meter districts and each district is made up of several water meter routes. To date, there are no GIS for the water meters located in these districts.
In order to begin the construction of this GIS, there was some Data Preparation of existing SDE tables. A 3 -Table join was necessary in order to get all of the pertinent information. The join was achieved using the SQL query wizard and included the following tables:
1. Parcel_gis Table
2. Address_gis Table
3. Utility_Meters_gis Table
Once the tables are joined and connected to the parcel layer, the many to one
Relationship is achieved.
The 3 tables were related based on the following fields:
Land key relates to item land key on parcel layer
Par_loc_id relates to item Par_loc_id in the Address_gis table
Address_Loc_id relates to the Address_Loc_id in the Utility_Meters_gis Table
This project concentrated on a Commercial Meter Study Area. The study area consisted of meters located in a commercial district in East Plano. The water meters from this commercial district served as a pilot study for the rest of the city.
Initially, there were some minor problems encountered. For example, the positioning of buildings and satellite locations made it difficult to achieve readings. Also, the gathering of data can be time consuming when required to occupy each individual meter location.
In order to solve these problems, I used DGPS (Differential Correction) instead of RTK (Real Time Kinematic), which provided more success for Satellite availability. I also used a Laser Rangefinder, which requires almost zero occupation time and can collect data while mobile. The area’s dense buildings made only 35% of structures GPS-observable with RTK. A second trip with a total station would have been required to obtain 3 to 5 centimeter accuracies. This made RTK inefficient and DGPS more feasible. DGPS showed that 75% or more structures were GPS-observable.
Once all the data was created, I then created an application using Visual Basic 6.0 and Map Objects 2.0. This proved to be very challenging since I have never programmed and did not know how to use either software. It proved to be successful. This application allows the Field Service Representative to enter the Location ID of the Parcel. Once the ID is entered, the map view displays meter information about the parcel and gives the field representative a visual interpretation of the area he or she is servicing. This application will allow field reps to find a meter location based on the information gathered through the use of GPS and tabular water meter data. The application also provides the user with information pertaining to the meter located on the specified parcel. While out in the field, the Service Rep can verify the meter and location information.
In conclusion, the GPS serves as a highly accurate means of gathering meter location data. This accuracy guarantees the validity of the GIS and all layers associated with the GIS. With the plan to inventory all infrastructures in the city, this project has proved the power and ease of data collection through use of GPS.