- SPECIAL REPORTS
- THE MAGAZINE
The town of Westfield, N.J., is like many other small municipalities; it has stretched resources and limited budgets to provide essential services for its residents. The town's engineering department, with four full-time employees, is responsible for maintaining and updating tax parcel maps, reviewing plans and coordinating stakeout work for road construction and maintenance. In recent years, the department has been assigned additional work to map its infrastructure and create layers for a comprehensive geographic information system (GIS). This work was required to be performed without affecting other ongoing work of the department. Fulfilling the town's needs has been possible with the help of a student intern and a trusty data mapper.
Town ProfileWestfield was founded in 1794 and has a population of about 30,000. The town is very small in area-just 6.73 square miles-and has approximately 10,000 land parcels and 389 streets. The total municipal budget is approximately $30 million. Under New Jersey law, each municipality is required to have a professional land surveyor to maintain its tax maps. Some jurisdictions use subcontractors to provide this service; in Westfield, that surveyor is Paul Horta, PLS, a full-time employee of the town and its sole surveyor. He works with three other individuals in the engineering department: George Dauber, project engineer; Barry Batzel, field engineer; and Gavin Gray, engineering aide. The foursome collect survey-grade field data to develop plans and specifications for road and sewer improvement projects, maintain and update tax maps and storm and sanitary sewer maps, and maintain an archive of some 9,000 surveys, deeds and filed maps dating back nearly 100 years. They are also increasingly tasked with collecting GIS-grade field data to help maintain infrastructure data layers for the town's GIS.
Initial planning of Westfield's GIS program began in 1997. Completed and functional in 2003, it now contains 20 layers of data. For the front-end program, Westfield used GeoClient by Spatial Data Logic of Somerset, N.J. The GIS layers are created using AutoCAD Map v5 by Autodesk and analysis is carried out using ArcGIS 9.0 by ESRI. Location and attribute data is gathered in the field using a Leica Geosystems' GS20 Professional Data Mapper with a Wireless Real-Time Corrections System (WoRCS) beacon package. The GS20 is a handheld GPS device for GIS data collection. The GPS receiver incorporates Leica Geosystems' ClearTrak multipath mitigation technology, and MaxTrak and HyperTrak solutions for optimal tracking in difficult conditions such as heavy overhanging foliage. The Coordinate Quality Monitor alerts the user whenever position accuracy falls below specified tolerance levels. The AT501 survey-grade antenna provides increased GPS positioning accuracy and performance, especially when collecting data in dense foliage. The L1 C/A-code and phase antenna is mounted on a lightweight antenna sash with telescopic rod for easy portability. The WoRCS, which consists of a belt-mounted Bluetooth communications hub and smart power supply, receives position correction data from Differential GPS navigation beacons to provide submeter position accuracy.
In 2003 Horta started a project to upgrade Westfield's old sanitary sewer maps for that layer of the town's GIS. The original maps, dating back to 1961, were drawn on linen to a scale of 1" = 200' and updated with pen and ink. He thought about redrawing the maps in AutoCAD, but the plotting of some manholes and distances between manholes have been found to be incorrect. So he decided it would be necessary to physically locate the manholes and plot them correctly on mylar. However, undertaking this project with conventional surveying methods would have taken too long and the project was not a high priority since the department is continuously busy with road improvement projects. In Westfield, the harsh winters, accompanied with road salting and de-icing, cause roadwork to be the town's No. 1 priority. To speed up the map updates, Horta considered using GPS technology to locate the manholes.
The GIS SolutionHorta attended a seminar sponsored by Leica Geosystems to introduce the GS20 data collector. The product matched the project type and accuracy requirements he was seeking. The Leica representative at the seminar, Frank Lenik, also a licensed professional land surveyor in New Jersey, gave Horta a brief demonstration of the GS20 outside the hotel. The two collected some data points outside, then went indoors and downloaded the GPS points into a laptop computer. In just minutes they had created an ESRI Shape file using the collected data. Because of the easy-to-use menu-driven interface and graphical map display designed to facilitate operation by inexperienced field crews with a minimum of training, Horta began to think about using summer interns to perform GIS projects, which the rest of his team were too busy to undertake.
The combination of interns and GS20s worked great. The first project utilizing both was the creation of a fire hydrant layer in the GIS for the fire department. To get the project up and running, Horta first instructed Gray on how to use the GS20; training took only a couple of hours. During the next two months, Gray and college intern Jake Lazarowitz located 700 hydrants in Westfield. At the end of each day they downloaded the day's project area into Leica's Windows-based PC GIS DataPro software and then transferred the GIS points into AutoCAD Map. GIS DataPro offers feature and attribute level controls, GPS post-processing, editing tools and data export functions, all from an ESRI Shape file format. The software program also supports Bluetooth data transfer with the GS20 without cables or docking station hardware.
By the end of the summer, Gray and Lazarowitz had added the complete hydrant layer to the GIS. "The GS20's job creation and data collection procedures were simple to pick up after only a few days," Lazarowitz says. "The unit works well with the external antenna and WoRCS belt attached. I have everything in a small backpack and it is light and comfortable enough to carry around all day."
Gray and Lazarowitz had set up an accuracy tolerance of 3 feet to locate the hydrants, and by using the WoRCS belt-mounted communication hub and an AT501 survey-grade antenna, they were able to achieve this accuracy and better throughout most of the data collection. "This has given me a great opportunity to learn about surveying and GIS," Lazarowitz says. "I am getting a better understanding about the necessary steps that it takes to build a proper GIS and why collecting accurate points is important."
Future MappingHorta and his team are now working on mapping the sewer manholes. It is a part-time job, sandwiched between higher-priority road projects, but they have found that it's easy to pick up the GS20 and go out for a couple of days to gather data whenever they have the time.
As of May 16 of this year, Westfield's college intern started to collect sanitary manhole locations on a full-time basis throughout the summer, perhaps collecting data on 20 to 30 manholes per day. GPS data collection will also include measuring the invert. Horta hopes to have almost all of the town's manholes located and mapped by the end of the summer. Following that, the team plans to map the town's storm water outfalls according to the New Jersey Department of Environmental Protection's new requirements.
The solution to invest in an efficient GPS data collector and hire interns for additional labor support is aiding the engineering department of Westfield to complete GIS projects more rapidly and within the constraints of its budget. As the town's needs grow and change, Horta and his team are confident they will continue to be able to serve Westfield efficiently and effectively in the future.
Spatial Data Logic: www.spatialdatalogic.com
Leica Geosytems: www.leica-geosystems.com