3D Laser Scanning Scores Topographic Survey Touchdown
- Addressing a Changing Scope and Scheduling Difficulties
- Managing the Changing Scope with Scan Data
- Providing Deliverables to Multiple Clients
- Estimating Results Compared to Conventional Methods
- Thinking Outside the Box for the Best Results
The Land Group, a multidisciplinary firm based in Eagle, Idaho, has worked with the Vallivue School District and Design West Architects for over 25 years on numerous K-12 school projects. In 2013, Design West Architects and The Land Group were selected to complete architectural and site design work for a new district high school and existing facility improvements funded by the passage of a school facilities bond. Based on a long history of successful projects, the Vallivue School District and Design West Architects were confident in the ability of The Land Group to deliver a successful project.
The Land Group utilizes an integrated approach to all projects, and they quickly assembled a multidisciplinary, in-house team to tackle this project. Matthew T. Adams, landscape architect, acted as overall project manager and led the athletic facilities design; Gabe Welz, civil engineer, led the grading, drainage and utility design; while Bill Davis, land surveyor, led the topographic survey effort. Having an integrated design team early in the process is one way that The Land Group consistently ensures their clients successful project outcomes.
On public school projects, the scope is rarely fixed. Unanticipated site conditions frequently arise that need repair during the early phases of design, and budget money often gets shifted around to address current district needs and concerns. Adams and Davis found it necessary to expand the area planned for the topographic survey several times.
This continuing change of scope led Davis to think that the company’s recently purchased Leica ScanStation C10 laser scanner was the best tool for this job. It would allow them to choose a small window of time for the scans and capture all the data they needed in just one trip. If the scope and program continued to be adjusted, the team wouldn’t have to make return trips to the site for additional survey data.
Scheduling the scans required a high level of coordination with the project owner. The fall semester of school was underway, and the 1,900 students attending the high school had programmed activities in the stadium six days a week for physical education, athletics and other extracurricular activities. “With the ongoing use of the site, there was just not going to be an opportunity to get back in without disturbing school activities,” Adams said. “Completing our field work in a single day was critical.”
Adams coordinated with the principal and the district’s maintenance crew to identify a time the survey crew could be onsite. Thanks to the flexibility of the survey crew, they were able to schedule the survey during the school’s Thanksgiving break.
After the preliminary research for record data was completed, the team discovered that record drawings for utility infrastructure in the stadium were not available. The only way to obtain data on existing utilities would be through meeting with school district facilities staff. The Land Group coordinated the date of the topographic scan with the district contact to ensure he would be available to provide the location of known utilities on site.
Although the process of identifying the location of utilities with the facilities staff added a significant amount of time to the survey process, it was critical to the success of the project. Even with this delay, the survey crew was able to gather all of the topographic data they needed within 12 hours to avoid affecting the school’s activity schedule.
The design team discovered a number of issues when they examined the scan data. “The original running track wasn’t constructed correctly,” Adams said. “When we began to design the new track to the correct grading requirements, we identified many challenging tie-ins to the existing bleachers, football field, and surrounding improvements.” The team returned to the original scan several times to pull more data and get more points from those specific areas to troubleshoot and fine-tune the design.
“Our biggest challenge was the ongoing expansion and change of scope,” said Davis. “Capturing so much more information in our single site trip enabled us to manage any potential scope creep and avoided any additional costs for the owner.”
The team had a depiction of the existing bleachers and grand stand area, which helped them when they needed to work with the architect on some ADA improvements, as well as press box improvements.
“The architect was really pleased because it gave him data he didn’t expect to receive,” said Adams. “Picking up that bleacher information gave us all the data we needed to look at access to the bleachers and the press box, as well as the sightlines from the press box and the bleachers to the track and football field.” A regular topographic survey done with GPS or other conventional methods would not have provided any of this information that became critical during the project.
“From the design side,” Adams said, “the ability to capture the bleachers was really incredible.”
Like most public school projects, this one had multiple clients, each with their own requirements for deliverables. The owner, the Vallivue School District, simply needed a 2D map in order to complete minor improvements and repairs on their own. With the assumption that the original track had been constructed correctly to meet required standards, the landscape architects and civil engineers did not anticipate needing the enormous amount of survey data that was eventually required. The Land Group’s history of K-12 school projects led them to plan ahead and anticipate that topographic data would be needed for several different disciplines working off the survey product.
The Leica ScanStation C10 was the tool the team used for 90 percent of the topographic survey. They also used GPS and conventional methods to help with some of the outer limits and establishing the horizontal and vertical control network to be used. To manage the processing of the data and the point cloud registrations, the team used Leica Cyclone software.
It was paramount that design staff be able to use their CAD based skills and efficiencies instead of training on new software. To achieve this goal, The Land Group used the Leica CloudWorx plugin for AutoCAD, which allowed them to take advantage of the 3D point clouds directly within AutoCAD. Once the data was registered into one overall point cloud, they were able to extract data as needed to produce the CAD deliverables.
“In our office,” Adams said, “we consider our own civil engineers as clients. They use the topographic data to do extremely detailed design. Providing them the best possible data is critical to project success. The deliverable to our in-house clients, our engineers, was a very robust 3D CAD file which enabled them to complete the detailed design work.”
The Land Group survey team would typically use GPS and a total station to gather the necessary topographic survey data for a project of this type. However, by using the Leica ScanStation C10 for this project, Davis estimates that field work was reduced by nearly three days and likely eliminated several return trips to the site.
The time initially spent in the field was reduced by at least half, but more significantly, 3D laser scanning provided the information the design team needed three months later when they needed to create a more site-specific design and provide design for a larger area than initially anticipated. Rather than attempting to schedule another visit to the field in person, the team visited the site virtually through the information already stored in the database.
Russ Hepworth, a civil engineer at The Land Group, pointed out an additional benefit the laser scanner has over the total station: “Even when you’re doing a tight topographic survey, the points are usually 10 feet apart. The standards of the track and field stadium require much more specific data, and we normally have to send crews back out there to shoot those points.”
At the high school level, the design of the track must be very exact and meet state and national standards. If it isn’t designed and constructed correctly, the school is unable to count any records that are set, and they aren’t able to host district or state events. The correct topographic data is essential to creating a correct grading plan. Without it, the track could be built incorrectly. With the scans, all that information is already at hand. “This saves weeks of time both on the design and the fieldwork itself,” Hepworth said. “It’s hard to measure that cost in dollars, but time is money, and you’re saving weeks’ worth of time in every 10 feet.”
“That equates directly to construction, as well,” Adams said. “If we miss some sort of anomaly in the grade in that 10 feet, then the contractor is going to have to stop and wait for us to come up with a solution.”
The design did not leave any loose ends, and the owner does not expect any change orders or delays in the field. The design process was completed quickly, and ultimately the contractor will have enough data to prevent surprises. Beniton Construction, the construction management firm building the project, was impressed by the amount of data provided and could see the advantage the scanning process provides to the whole project. The company has since hired The Land Group to perform scans on several additional projects.
Even though not everyone who used the data was a direct first point-of-contact, they all benefit from the results. “The school district may not know it,” Adams said, “but we’ve reduced the potential for change orders. They’ll be more satisfied with that, even though they only requested the 2D topographic map.”
Pleased with the outcome, The Land Group entered the project in the Civil/Survey category of the Leica Geosystems 2014 HDS Plan Contest, where it scored a second-place award. More importantly, however, the project serves as a goalpost for future endeavors. “This is one of the first big projects we completed with the C10,” Davis said. “It taught us to think outside of our normal box regarding control points and instrument setup, and ScanStation setup.”
The team learned to set up in strategic locations to capture data from a different perspective, rather than setting up in the places where they would normally see features. They also discovered how to achieve just the right amount of overlap from each scan location to the next. From a technician level, it helped them in drafting similar projects. “Learning how to interpret the point cloud and using CloudWorx in the CAD environment was a great way to use the data,” Davis said. “From using it extensively on this project, we quickly decided that CloudWorx will be a valuable tool for us to complete similar topographic surveys.”
Making better decisions is simplified with the ability to look at any object from any angle and any distance — all from the data collected in a single site visit. “Having that capability is very powerful,” Davis said.
Beth Wilson is a freelance writer based in Bermerton, Wash. For more information about The Land Group, visit thelandgroupinc.com. For additional information about 3D laser scanning solutions, visit leica-geosystems.us.