Fast, Accurate Geo-referenced Imaging To Go
Denver is one of America’s fastest growing cities. But with this growth comes new challenges, such as managing the increase in traffic that is sure to follow. As part of its efforts to address this challenge, the Department of Transportation and Infrastructure (DOTI) is working to update the city’s public transit system – an effort that included inventorying the location and types of bus stop amenities. For this, they turned to All Traffic Data Services, LLC (ATD) and Felsburg Holt & Ullevig (FHU), who completed the task using the Trimble MX7 and ESRI’s ArcGIS platform.
In the past, ATD, a traffic data collection company with nearly 20 years of experience working with public and private clients of all sizes, would have done this type of inventory manually. “This meant driving to each location and taking a photo of the guardrail, sign or whatever was being counted,” says Dawn Boivin, Chief Operating Officer at ATD. “But with 3,000 bus stops spread across more than 1,750 miles to be inventoried, this project was way too big to do it the ‘old school’ way.”
Mobile mapping provided an ideal combination of speed, accuracy and the ability to capture comprehensive information in a single operation. In consultation with Frontier Precision, ATD selected the vehicle-mounted Trimble MX7 Mobile Imaging System for the project.
The Trimble MX7 captures 360-degree, georeferenced images while moving at up to highway speeds. For this project, ATD used the MX7 to collect imagery along the desired corridors and visually complete the amenity inventory. “After receiving the corridor routes via ArcGIS, we simply installed the MX7 on the vehicle’s roof and proceeded to the particular corridor set up for that day,” explains Boivin.
BACK AT THE OFFICE…
The collected data was downloaded and processed using POSPac MMS and Trimble Business Center software (TBC). POSPac MMS provides direct georeferencing of mobile mapping sensors, while TBC provides data management, visualization and computations.
The georeferenced images were then uploaded to Mapillary, which was used as a simple platform for
accessing and sharing the imagery. “Once in Mapillary, we used ArcGIS to capture an image of each bus stop,” says Boivin. “We then input the assets into a spreadsheet, which was later integrated into the final geodatabase provided to the client.”
FHU, a multidisciplinary consulting firm with a focus on GIS services, played a critical role in developing this geodatabase. The company provided Denver with an attributed ESRI 10.x file geodatabase with detailed metadata that included capture dates, spatial extents and geospatial processes executed to populate the database.
“While the imagery captured by the Trimble MX7 was stored separately from the final bus stop amenity inventory geodatabase, it was beneficial to enable geodatabase file attachments and extract image snapshots from the MX7 imagery and physically embed them into the final geodatabase,” says Megan Ornelas, GIS Manager at FHU. “This delivery method integrated seamlessly with Denver’s existing GIS infrastructure.”
DOTI is using this data to create a consistent base inventory of all bus stop amenities, identify deficiencies in the existing inventory and prioritize improvement projects.
ACCURACY, SPEED AND SAFETY
The DOTI project was ATD’s first experience using the Trimble MX7. However, due to its unprecedented accuracy, speed and safety, it won’t be its last. “Having precise location information made locating the stops much easier,” says Boivin. “It also proved valuable when it came time to add the images to the city’s GIS and asset management systems.”
Using the MX7 also allowed for a huge time savings. “If we had to physically go to each stop and take a picture, the project would have taken up to 400 hours,” says Boivin. “With the MX7, we collected the field data in just 100 hours.”
Boivin also notes how the MX7 helps improve safety. Instead of using an off-speed vehicle that creates a traffic hazard, the MX7 allowed ATD to collect data while driving at the speed of traffic – a feature that made the process safer for everyone.
Even though ATD has only used the MX7 for asset management, they see the potential for using it
with a range of visual-based needs, from evaluating existing conditions along a corridor to measuring the
progression of a construction project or monitoring signs and signals.
“Because the amount of information available from the MX7 is so diverse, it gives you the ability to capture infinite data,” says Boivin. “This, and the fact that it’s so easy to use, is why we plan on making it one of our go-to solutions.”