Measure twice, cut once: Using drone data to calculate concrete volume

Earlier this year, EMJ completed an expansion at Ruby Falls, a tourist attraction in Lookout Mountain, Tenn., that boasts the nation’s largest public underground waterfall. Our team constructed a new lobby, retail space, pedestrian mall, and more next to the original, historic castle that sits more than 1,000 feet above the underground waterfall.

The expansion required removal of a significant amount of rock to create a pad for the new construction. Considering the site’s location on a mountainside above an underground cavern, the team carefully drilled out the rock section by section, rather than blasting. As documented in a recent Ground Up podcast, the rock removal process required precision planning, logistics, and execution by all project team members. It also required careful consideration for how to prepare the resulting site to endure the elements for many years to come.

Among those considerations was waterproofing and the best method to ensure the exposed rock could withstand the elements. Of particular concern was a void between the new building and the rock wall. This gap was created when the team carved out the rock to create the building pad. The design team presented two options for EMJ to consider: apply a vinyl-waterproofing product or fill the space between the building and the mountain with concrete.

But, here was the catch. While the team could estimate the cost of the vinyl waterproofing, it was impossible to measure the gap and estimate the cost of the concrete.

The team called on Caleb Wickersham, EMJ Virtual Construction Engineer and licensed drone pilot, who had already flown the site and created a 3D model of the mountainside using photogrammetry.

Caleb layered the architect’s building model next to his mountainside model. Using his previous calculations, he was able to determine the volume of the space between the building and the mountain, which provided the amount of concrete needed to solve the waterproofing issue.  From this, the team calculated the concrete cost, and in comparing it with the vinyl-waterproofing cost, the vinyl product was the more cost-effective and prudent option for Ruby Falls.

There is an old adage that applies to construction, “Measure twice and cut once.”  In a figurative sense that means to plan and prepare in a careful, thorough manner before taking action. Using construction technology, that is exactly what the Ruby Falls team did, helping make sure its recommendation to the client was accurate.

Check out this video of Caleb’s handywork.

Related story:

EMJ’s Chattanooga team wraps up Ruby Falls expansion


EMJ’s Chattanooga team wraps up Ruby Falls expansion

After 14 months of meticulous planning and diligent work, EMJ has completed the Ruby Falls expansion in Chattanooga.

Located over 1,120 feet below the surface of Lookout Mountain, Ruby Falls boasts the nation’s largest and deepest waterfall open to the public. The site has become one of the most popular attractions in the Southeast, welcoming thousands of visitors each year.

With this expansion, visitors will now enjoy a new entrance lobby and pedestrian mall, as well as updated parking, ticketing, retail and restrooms. Other additions include renovated office space and enhanced observation of the city.

Due to its location and landscape, the project provided some unique challenges.

“The biggest challenge was the hammering out of rock,” said Ryan Colbert, EMJ Project Engineer. “We had to install rock drapes to mitigate the risk of falling rocks. That process presented its own challenges, but we were able to overcome them.”

Much like all projects of this magnitude, teamwork played a crucial role.

“Our framers came through for us really well,” Colbert said. “Logan Moore really stepped up to the plate and helped us where we needed it. They all went above and beyond what we asked of them.”

Ruby Falls and EMJ share a storied history in Chattanooga, so it is fitting that the two teamed up for this project.

“Our client relationship with Ruby Falls is very strong,” Colbert said. “They are very pleased with our work, and there’s a good chance we will do business in the future as well.”

Congratulations to the EMJ team on the project: Superintendent John Rudez, Project Engineer Ryan Colbert, Superintendent Taylor Copeland,  Project Manager Matt Elliot, Director of Construction Gary Gibson, Superintendent Lance Lindsey, Vice President of Preconstruction Alex Miller, Senior Administrative Assistant Tina Brogdon, and Project Accountant Robin Phillips.


Related articles:

EMJ to begin construction on Ruby Falls expansion

Ruby Falls team sets expectations through mock-ups

Photogrammetry offers easy, accurate solutions for owners and trade partners

3 reasons to request mock-ups on your next project

A mock-up is a full-size structural model made with the exact construction techniques and materials that will be used on a project. Typically, materials for mock-ups are ordered in small portions, then, executed by the project team in advance of the rest of construction.

In preparation for Ruby Falls’ expansion, the EMJ Chattanooga team performed mock-ups of various sections of the project. John Rudez, EMJ Superintendent, and Matt Elliot, EMJ Project Manager, explain three benefits of these mock-ups and why you should request them on your next construction project.

1. Confirm (or clarify) your vision
Mock-ups give clients, contractors and project teams the opportunity to assess a three-dimensional representation of a design, so that functionality, aesthetics and quality can be evaluated down to the smallest detail.

They take proactive planning and additional time to implement, but allow the client to make revisions to the project’s design before moving forward into construction. Additionally, materials for mockups are ordered in small portions so there is minimal waste if the client decides to go in a different direction.

“[The mock-ups] gave us a chance to look at the actual model and add those details in, in order to give the owner exactly what they wanted,” Elliott says. “There were many things that came out of this that helped the team put together the best possible product for the owner.”

Until you can see and feel the finished product, it’s hard to know exactly what to expect. Mock-ups remove any surprises and ensure owners fully understand various physical aspects of their project before it’s built.

2. Set expectations with your team
Mock-ups serve as a “trial run” for the project team to complete a task while learning what is important to the client. Superintendents can use this opportunity to set expectations, guide the team, and make changes to improve efficiency before construction begins.

mock-up, concrete slab, Ruby Falls, preconstruction, quality, superintendent

“By going through [a mock-up], our subcontractors learn the steps and understand their roles, and our owner understands and his expectations are set,” Rudez says.

“It’s a very heuristic approach to the building process, and allows the subcontractors involved to practice that they’re going to be doing, and allows them time to get prepared for that, so in the end they end up doing the project faster and more efficiently,” Elliott adds.

3. Pinpoint any potential problems
Even the most experienced construction professionals interact with new teams, materials, and processes on a daily basis. Mock-ups show pain points in the building process that otherwise may not be visible until construction—when any changes or errors would be costly and time-consuming.

“Mock-ups allow our team to pinpoint any and all issues well in advance of the construction phase,” Rudez says. “Knowing that we have several different types of finishes in different products, and some products that we are unfamiliar with on the job—I find it very helpful.”

Although creating a mock-up may seem like an additional expense during preconstruction, it could end up costing more to later repair unforeseen errors.

mock-up, concrete slab, Ruby Falls, preconstruction, quality, superintendent

“During the mock-up process, we found out several things: details that weren’t right or didn’t line up like the owner had anticipated,” Rudez continues. “Little things that they really hadn’t maybe thought about or detailed fully on their plans.”

You understand your project goals and vision better than anyone. But with the right leaders and valuable tools like mock-ups, your team should be in-sync with you to execute your project to achieve your goals.

Related articles:

EMJ to begin construction on Ruby Falls expansion

Ruby Falls team sets expectations through mock-ups

Photogrammetry offers easy, accurate solutions for owners and trade partners

Photogrammetry offers easy, accurate solutions for owners and trade partners

A site capture of Firestone in Opelika, Ala., offers measurements at 1-inch accuracy through use of survey control points.


Construction of the Firestone store in Opelika, Ala., required a series of cut and fills before construction began. Wanting to ensure that the site’s grade was maintained and that stormwater drainage requirements were achieved, the EMJ Special Projects team enlisted the help of Caleb Wickersham, Virtual Construction Engineer and licensed drone operator.

Using GPS coordinates and other data, Caleb conducted programmed, automated flights along the same path at each stage of the site’s preparation. During the flights, the drone captured high-resolution images of the site from which Caleb applied photogrammetry.

“Photogrammetry offers construction teams the ability to capture measurements and record the site how it was at the time of flight,” said Caleb.

The measurements obtained through this process are within an inch of accuracy and offer endless applications in the construction industry.

“It allows us to go back if something goes wrong and see where and when the problem occurred or can be used to hold project participants accountable for their contracted responsibilities,” said Caleb. “Taking measurements can also offer data that would otherwise take extra time, effort and money to obtain. For example, after a drone flight at the Hampton Inn site in Decatur, Ga., we captured the height of surrounding buildings. This was then used to discuss crane logistics and security camera locations for the site.”

At EMJ Construction’s Ruby Falls project in Chattanooga, Tenn., the team requested Caleb’s help in determining the amount and estimated cost of concrete.

“It allowed the project team to see how much concrete would be needed to fill the space between a wall and cliff face and make decisions based upon that volume estimate,” said Caleb.

This photogrammetric 3D model was used for confirming measurements at Ruby Falls. Green photo projections represent where the photos were taken in 3D space.


Drone flights cost roughly $500 per flight, but the cost can vary based on the number of flights and the job site location. Teams receive their drone deliverable package typically within 48 hours of the drone flight, and Caleb and his team can provide them anything from an orthomosaic sitemap (a top down view of site at high resolution) and volumetric calculations to 360 photos and video.

“Additionally, EMJ clients are able to see the data as we capture it,” said Caleb. “This allows them to see a timeline of the building as it rises from the ground and assists in communicating progress. Subcontractors also benefit from the data and the availability of an active, up-to-date map of the site as they develop their execution plans.”

For more information on photogrammetry or to enlist the Construction Technology team’s help with a project, contact

Caleb Wickersham joined EMJ Corporation in 2017 and is focusing on building EMJ’s field technology capabilities, such as drones, Matterport and laser scanning, as well as assisting with BIM coordination and other related tasks.

EMJ’s 10 most-read blogs of 2017

EMJ published more than 80 stories on in 2017. In celebration of the new year, we’ve compiled a list of the top 10 most-read blogs of the year. Check out these popular stories, and visit our What’s New page for more news.

1. Great construction superintendent
While this blog was published in late 2016, it continues to  be discovered and read online. Pulling in more than 1,100 readers in 2017 through Google searches alone, this blog remains a fixture among EMJ’s most-read blogs.

5 qualities of a great construction superintendent

2. Branch Technology & a 3D-printed house
Published just a few weeks ago, this popular story already ranks number two in readership. As construction of this groundbreaking project gets underway in 2018, this is sure to remain a hot topic.

EMJ, Branch to build the world’s first 3D-printed house

3. EMJ ranks #69 among Top Contractors
Engineering News-Record ranked EMJ #69 among its Top 400 Contractors in 2017, and the news traveled fast across social media and our website.

EMJ ranks #69 on ENR’s list of Top 400 Contractors

4. Outstanding employee performance
Our blog recognizing the top performing EMJ employees of 2016 has been read far and wide by proud families, friends, colleagues and many more.

Employees awarded Jolley for Outstanding Performance

5. Market City Center opens
The opening of Market City Center, a 10-story, mixed-use development in downtown Chattanooga, Tenn., garnered a lot of interest on our website. The project was the tallest building to be built in Chattanooga in several years, and the efficient and well executed project was a big story in the scenic city.

Market City Center opens in Chattanooga

6. Burt Odom on servant leadership
Tying in to our company purpose, to be people serving people, EMJ CEO and President Burt Odom discussed leadership with CityScope Magazine, expressing what he believes it takes to be a great leader and how a company develops leaders.

Burt Odom: ‘Great leaders are servant leaders’

7. Ruby Falls expansion
EMJ began work on an expansion of Ruby Falls, a popular tourist attraction in Chattanooga in Spring of 2017. Since then the team has been slowly excavating rock from the side of Lookout Mountain, Tenn., to make way for the additional facilities. It’s no surprise this blog has been well read, considering the uniqueness of this project.

EMJ to begin construction on Ruby Falls expansion

8. What to look for in a construction job
EMJ’s recruiting team worked with our writers to develop this fun blog, outlining what those seeking a job in the construction field should look for in their next employer.

6 things to look for in a construction company

9. The debut of EMJ Special Projects
Accent Construction was rebranded as EMJ Special Projects in late Spring of 2017. This news traveled fast and received a lot of attention online and on social media.

Accent Construction is now EMJ Special Projects

10. Guiding construction technology
Jonathan Deming, EMJ Director of Construction Technology and BIM, was featured on the blog in May. Emerging technologies in the construction industry and how they are applied on the job were a hot topic throughout the industry in 2017 and will continue to be in 2018 as more construction companies adopt these innovative tools.

Guiding teams into the future with construction technology

We hope you enjoyed our look back at 2017. These top 10 blogs are only a glimpse of the content published this past year. Click on What’s New at the top of the page to view more.

Ruby Falls team sets expectations through mock-ups

EMJ’s Chattanooga team recently performed a polished concrete mock-up for the Ruby Falls project, giving the client and the team and a better understanding of what’s to come during construction.

A mock-up is a full-size structural model made with the exact construction techniques and materials that will be used on a project.

mock-up, concrete slab, Ruby Falls, preconstruction, quality, superintendent

“Mock-ups serve two purposes: to extract expectations from the client and to communicate what your team will deliver,” said Jonathan Horne, EMJ’s Director of Quality Assurance. “Mock-ups allow us to get the client’s feedback on our work at the preconstruction stage rather than after the task is completed on the project.”

The mock-up gives clients, contractors and project teams the opportunity to assess a three-dimensional representation of a design, so that functionality, aesthetics and quality can be evaluated down to the smallest detail.

“We want to present the true expectation so our client understands what they’re going to get when we are finished,” said John Rudez, Superintendent of Ruby Falls in Chattanooga, who showcased the mock-up in a recent video.

mock-up, concrete slab, Ruby Falls, preconstruction, quality, superintendent, John Rudez

Although creating a mock-up may seem like an additional expense during preconstruction, it could end up costing more to skip this step and later repair unforeseen errors.

“Any time you have a specialty finish it’s a good idea to perform a mock-up,” said Matt Elliott, Project Manager at Ruby Falls. “It not only aligns expectations but also ensures that the finish matches the consistency and pattern the owner desires.”

Understanding the difficulty of translating polished concrete to the client, the Ruby Falls team determined that a concrete slab mock-up, among several others, would be beneficial during their quality management planning meeting. They then reached out to the learning team to document the process.

mock-up, concrete slab, Ruby Falls, preconstruction, quality, superintendent

“We wanted to take the client through the process and outcome, and then realized that documenting it also served as a learning opportunity for our other construction teams,” said Elliott. “We knew that mock-ups were the best way to ensure that what we intend to deliver will meet and hopefully exceed expectations.“

Still in the early construction phase of the Ruby Falls project, EMJ’s team is beginning to focus on the end product, but with proactive techniques like mock-ups at the forefront of construction, our client experience is sure to exceed expectations.

“There is great value in mock-ups for our team by building trust, expanding knowledge and improving the client experience,” Horne added. “We know the risk of an unhappy owner is far greater than the cost to do it.”

Above: The EMJ team mocked up a wall section of the building to convey building envelope details, aesthetics, and more for the client at Ruby Falls.


Related stories:

EMJ to begin construction on Ruby Falls expansion


EMJ to begin construction on Ruby Falls expansion

Ruby Falls announced Tuesday that EMJ has been selected to oversee the attraction’s expansion, both phases one and two.

Home to America’s deepest cave and largest underground waterfall open for public viewing, Ruby Falls has hosted millions of visitors since its first tour in 1930. It features a 145-foot waterfall located 1,120 feet beneath the surface of Lookout Mountain in EMJ’s hometown of Chattanooga, Tenn.

“We are always thankful when we have the opportunity to work on a project that positively impacts our hometown,” said Clint Dean, Executive Vice President of EMJ Construction. “Ruby Falls is a notably unique and exciting construction project, which is extremely important to our community.

“We are looking forward to helping enhance this historical landmark while delivering an exceptional client experience to our friends at Ruby Falls.”

Both Ruby Falls and EMJ have strong legacies in Chattanooga making the synergy a natural fit. The project includes updated parking, ticketing, retail, restrooms, office space and a new entrance lobby, intended to improve queue lines for the cave tour and the overall guest experience. Other additions include a pedestrian mall and enhanced observation of the city.

“From the moment our discussions with EMJ started it was obvious that their team understood the historical significance of this venture,” said Hugh Morrow, president of Ruby Falls.

“They have also worked extremely hard to provide solutions for Ruby Falls, but more importantly for our visitors and guests as we construct this unique project. Having a team that includes our architect PGAV Destinations and the local construction expertise of EMJ gives us a great path towards success.”

PGAV Destinations is a global leader in the planning and design of unique destinations. Now entering its sixth decade, the practice has evolved to become the ideal destination-consulting partner. PGAV’s key clients include industry leaders such as SeaWorld Parks and Entertainment, the Biltmore Companies, Bass Pro Shops, Universal Studios and many others. Recent assignments include the Grand Canyon, Space Shuttle Atlantis and the Georgia Aquarium.

Watch this video to learn more about the history of Ruby Falls and the expansion plans: