A technology can be seen as being truly revolutionary and impactful when new uses for it continually arise. Case in point is 3D LiDAR scanning, which has already proven invaluable in everything from aggregate quantity calculation to plant mechanical layout, to power line sag monitoring and more. So when Sisemore-Weisz & Associates (SWA) landed a contract to help the city of Tulsa verify compliance to the Americans with Disabilities Act (ADA), the strengths of 3D scanning immediately came to mind. Shooting at more than 20 locations throughout the city, the civil engineering/survey specialist was able to present a deliverable to their client that could be used to identify areas that were either in compliance with the ADA or in need of work to make it so.
Getting into the Act
A specialist in engineering-based site design, with survey strengths in ALTA work and high-end construction layout, Sisemore-Weisz & Associates has four-plus decades of serving the Tulsa area. Even though the firm has tackled a broad range of projects in its time, when the contract for the Tulsa/ADA job was won, it still turned some heads, according to Shawn Collins, SWA’s chief of parties.
“The scope of the project was certainly on the larger side,” he says. “The city compiled a list of 20 municipal locations that could possibly be out of compliance with the ADA and wanted us to provide the ideal means for them to make that determination. That list included a number of municipal buildings, several fire houses, a court building, the Tulsa Animal Shelter, the city’s oldest cemetery, the 9-1-1 call center, the Tulsa Police Department’s headquarters, Tulsa City Hall, the Oxley Nature Center, the Bank of Oklahoma Center (Tulsa’s civic arena) and the Tulsa Zoo. All of these structures were built at different times, but still had to be reviewed for compliance.”
Passed by Congress and signed into law by the late President George H.W. Bush in 1990, the Americans with Disabilities Act (ADA) is a federal law that provides civil rights protection to individuals with disabilities in, among other areas, public accommodations. As such, the act prohibits discrimination on the basis of disability by calling for the removal of architectural barriers. Though many think the law applies only to new construction — assuming that older facilities are “grandfathered” in — because the ADA is a civil rights law and not a building code, older facilities are also required to be accessible to all. Such was the case with many of the structures on the list generated by the city of Tulsa.
Tiny Deviation; Big Challenge
The challenge of the compliance survey project was not only in the number of structures needing verification work, but also in the detail to which those surveys had to conform. Collins says that really drove the direction in which they chose to go.
“On this project, we could not approach things conventionally with a 50-foot grid and hand topo — or even a 25-foot grid,” he explains. “The city was looking for accuracies within a ¼-inch or less, and the only way we could achieve that was to work with a 6-inch grid with 2/10’ contours. Given the size of the overall project, if we were to take a hand topo shot every 6-inches, it would have literally taken us forever. However, we already owned a Topcon GLS-2000 scanner and felt that it could provide the solution we needed — we could not have been more right.”
Convinced their decision was the correct one, Collins’ team set out to scan the first structure, Tulsa’s Transportation Management Building. According to Jimmie Hendrickson, SWA project manager, the number of scans per structure varied — anywhere from 10 to 300 — as did the data generated from those scans.
“Our goal was to capture data that could then be used to assess whether or not a particular area of a structure — a sidewalk or an entryway, for example — complied with the directives set out in the ADA,” he says. “Truth be told, we were still working our way through the best way to get where we needed to be. At the outset, we were sending the client CAD files, because that’s where his comfort level was. However, about halfway through the project, after visiting our office and seeing all the tools available that could expedite the project, he switched over to Civil3D. Doing so allowed him to work in a 3D world, and we showed him how to handle gradient lines and see real-time percentages of grades on his model. That opened things up and the ball started rolling.”
SWA’s Topcon GLS-2000 is a full-featured scanner that has proven ideal for capturing existing, as-built conditions in a host of applications. Compact and lightweight, the dual mode instrument (selectable for Class 3R or Class 1M operation) can accurately capture a full 360-degree scan — including images — in less than three minutes. Providing both speed and versatility, the GLS-2000 offers a range of 350 meters, and is designed to pair with proprietary Topcon point cloud software (currently called MAGNET Collage) to quickly capture and process 3D point cloud data.
“While the scanner’s performance was key to making this project work, there is another reason we embrace that solution so much: it’s about accountability,” Collins says. “With the GLS-2000, if need be, I can sit down before my board of licensure and say that the scanner allows me to control the data; it is not the software doing the controlling. I use the software to verify the data that I’ve scanned; I can log it in my field book as having been done on a closed traverse with differential levels. I can run though the project, occupy backsight and traverse with my scanner and confidently say I have control. Simply put, I have all the checks and balances, as opposed to just setting up my scanner in an arbitrary position and marrying the input software, doing the target recognition and meshing it all together. That is the software taking charge, not me, the PLS, controlling it — and we won’t have any of it.”
One of the more challenging elements of the ADA scanning project involved capturing a number of areas at the Tulsa Zoo. The 91-year-old, 85-acre facility, which sees in excess of 700,000 visitors each year, is home to miles of sidewalks and dozens of entrances/exits that needed to be eventually tested for compliance.
“The zoo was truly a unique site to scan, given all the large spaces, houses for animal exhibits, concession areas and so on,” Hendrickson says. “Because the zoo alone consisted of over 300 scans, it made us realize just how much we appreciated being able to scan versus having to conduct a manual topo. The facility was built almost a century ago and has undergone a number of renovations, but many of those renovations were before the ADA was even a consideration, so we needed to capture a lot.”
He adds that it took about three months to do the field work at the zoo and just as long to clean the data up afterward. The fact that SWA’s customer was demanding such a dense pattern made it a challenge. “When you do something that tight, the scanner picks up things like the shrubs, leaves and so on,” he says. “But the ADA compliance review was wanting us to focus on any handicap parking areas, sidewalks and entryways, so the post-processing cleanup work kept us busy.”
I Never Metadata I Didn’t Like
One benefit of LiDAR scanning regularly cited by users is an ability to gather — and subsequently use — information that was not an originally intended target. SWA capitalized upon that strength, shooting “dome scans,” or a 360-degree scan around the instrument. According to Collins, that little bit of extra work can reap huge benefits down the line.
“The metadata that the GLS-2000 creates from the project can be invaluable,” he says. “While I’m scanning, I always try to shoot a broader window or a 360-degree scan. Yes, the customer is paying for a specific area and that’s what I’ll deliver. However, if they call me back saying they need to get another 200 feet or want to see a different side of the road, I already have the metadata with everything they need. A little bit of extra effort has now eliminated the need to go back out and revisit the site.”
Collins adds that the initial efforts to choose and then purchase the GLS-2000 scanner were helped greatly by the team at GeoShack. According to Chad Long, GeoShack BIM sales specialist, while the relationship between the two companies goes back quite a bit, focus on the scanner came about just a couple years back.
“At that time, Sisemore was involved in an airport project for which the required deliverable was a point cloud file,” he says. “They contacted us through the Tulsa location, told us their situation, and we set them up with the GLS-2000 which we knew was the solution they needed. I went up to Tulsa, met with Shawn and trained him on the instrument, which clearly helped make that project a success. It’s great to hear they continue to benefit from it.”
Field work for the scanning effort was daunting, lasting an entire summer and well into autumn. For each site, Hendrickson says they started by bringing in Tulsa state plane control, then running a closed level loop through all scan positions and importing the control file (.CSV) into the scanner.
“We scanned all positions using the instrument’s ‘Occupy Back Site Check’ procedure to check control before scanning and recording field notes for future use,” he says. “In the office, we kept our scan position number the same as the control point we occupied, which helped when we registered the scans using the Topcon software. In that software, we also eliminated all the extraneous data; having only what we needed, we created the point cloud and exported the file to our server.”
The next step in the workflow involved utilizing TopoDOT from within Bentley System’s MicroStation to import the cloud data, then using TopoDOT’s tools to create line work and a grid.
“Our line work for every sidewalk edge varied between 0.5 and 1.0 feet — depending on the slope — and our elevation grid was set to every 0.25 to 0.5 feet,” Hendrickson says. “After creating the line work and the outline of the building face, we generated our grid and saved the file as a .DWG (CAD) file. At that point, we opened the file using Civil3D. Once opened, we brought in the items created in TopoDOT — the line work, points, etc. — then used our template in Civil3D to label and contour the project, and sent the completed CAD file to the architect.”
With that file in hand, architects working with the city of Tulsa will review the scans, examine the surfaces in question, determine where any ADA conflicts might be, and, if needed, make the changes needed to bring it into compliance.
“This is an effort that is high on the city’s ‘to-do list,’ if you will,” Collins says. “We were happy to be a part of it, and it gave us all a better appreciation for how important the Americans With Disabilities Act really is. It was a massive undertaking and, given the tight parameters, one that really could not have been done using traditional survey techniques. Fortunately, we have technology like the GLS-2000 to make a project like this happen and everyone involved is pleased with the results. That, to me, says we did our job and did it well.”