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GIS/GNSS Data Collection Case Study: A Low-Overhead Solution

The city of Moncton, New Brunswick, Canada needed to overhaul its antiquated data acquisition methods while keeping overhead costs down. A new workflow comprised of a lidar unit, GNSS service, antenna and tablet, now identifies and catalogs hazardous low-hanging tree branches across the city. It’s an economic, user-friendly solution that nearly any employee can operate.

The Director of Operations of the Parks Department, Dan Hicks, oversees several city assets from municipal arenas to forestry in Moncton. Every municipality has standard operating procedures; when elements of these processes are automated, efficiency and reliability grow. Hicks and his team rightly predicted that a certain routine maintenance task—identifying and recording low-hanging tree branches—was ripe for automation. A hazard to vehicles and pedestrians alike, low-hanging tree branches require continual identification and removal to ensure people can safely navigate the city. In the city of Moncton, tree branches must be 15 feet (4.6 m) above street level and 8 feet (2.4 m) above sidewalks.

Sidewalk through a city park with gardens and trees on either side

Routine maintenance of parks and public ways ensures Moncton residents and visitors can safely navigate the city.

When Hicks described the traditional method of recording low-hanging tree branch locations, the opportunity for improvement became evident. “We did it before by driving by, jotting down addresses and identifying low-hanging branches by eye,” said Hicks. “It’s time-consuming when you do it that way: using pen and paper and driving. Drive, stop, write it down. Drive, stop, write it down.” Hicks and his team knew a more automated solution was possible. They presented the challenge to the team at their Trimble distributor, Cansel, who assured Hicks they could figure something out.

Cansel provided them with a simplified mobile scanning device made up of three basic elements. Attached to a company vehicle, a small lidar unit measures the clearance to the nearest solid overhead structure while a Trimble® Catalyst™ DA1 antenna captures the vehicle’s horizontal location to sub-meter accuracy. A Samsung tablet using a customized software application developed by Cansel handles the data from these two elements and delivers the output file.

Aerial screen shot of city streets highlighting trees with overhanging branches

Mapping low-hanging branches helps to prioritize and schedule the maintenance of trouble areas.

Trimble Catalyst, the subscription-based GNSS service, turns the Samsung tablet into a fully functioning GNSS receiver, providing positioning at submeter accuracy without the expense of traditional GNSS equipment. Using a tablet (or smartphone) as a GNSS receiver makes this setup more approachable for employees without experience using survey equipment. Anyone who is familiar with a smartphone can navigate the Catalyst software on their Android device. The small DA1 antenna and lidar unit are mounted by suction cups, making the setup easily transferable between company vehicles. “You can put it on a golf cart and measure clearances on sidewalks,” Hicks said, adding, “you can mount it to just about any type of vehicle.” Currently, the setup is attached to the foreman’s truck who gathers the tree data as a supplemental task to his normal duties.

Group of images showing the Trimble DA1 antenna mounted on a vehicle roof, and software running on an Android phone

The data collection system developed by Cansel is simple to operate and easy to transfer between vehicles.

When the drive is over, the customized application exports a comma-separated-values (CSV) point file to the city’s GIS technicians who upload the data to a city map in Esri® ArcGIS®. Hicks and his team review the map and then filter and sort the conflict areas as high, medium and low risk sites. The GIS map allows them to assess and schedule the maintenance of these conflict areas most efficiently, attending to high-risk sites before they become a problem for motorists.

Scenes of city parks in autumn and winter

Seasonal weather changes in Moncton routinely take down tree branches and create maintenance work for the city.

Hicks and his team are enthusiastic about the prospects of this new solution. Its simplicity allows employees without GNSS expertise or forestry knowledge to use it, which means purposeful, non-specialized work is open to more people. “You’re looking at a municipality with 650 employees in the city,” said Hicks, “and at any given time some of them are on modified duty. They might be able to drive a truck but not lift a chain saw, so you’re looking for productive work for them to do.” The ease of use makes this a task that any employee capable of reading a tape measure and driving can perform successfully. The subscription-based GNSS capability provided by Catalyst allows flexibility in planning when gathering data, without investing a lot upfront. “One could collect data over several kilometers per day,” Hicks said. It’s a clever upgrade that will benefit both the employees of Moncton and the citizens they serve.

"We suspected there was a way to automate this and get a little more data using Trimble technology. We reached out to the folks at Cansel who were able to find the ideal solution to our problem." ‒ Dan Hicks, Director of Operations of Parks Dept., City of Moncton