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"The versatility of robotic total station technology has become our digital bridge between concept and construction," says Paul J. Alexander, vice president of Straus Systems, a mechanical contractor based in Stafford, TX.

Founded in 1933, Straus Systems designs, fabricates and installs heating, ventilating and air conditioning (HVAC) systems for many commercial and industrial clients in and around the Houston area.  Much like other engineering fields, mechanical contractors rely on information technology in the way of 3D CAD/CAM software to design and fabricate increasingly complex systems.

Now, with the introduction of building information modeling (BIM) tools, techniques and methodologies, Straus Systems has begun to expand its capabilities and expertise to meet customer demand for the use of intelligent 3D models to facilitate construction. 

Paul J. Alexander, vice president of Straus Systems, says, "In terms of technology adoption, the shift to BIM as a design/fabrication tool is not a big deal for us – the greater challenge is finding ways to use the 3D data and models to drive efficiency and accuracy at the jobsite."

Field/office connections
For every pipe and duct in a HVAC system, there are numerous hangers, sleeves and other apparatus that must be positioned within the structure to support the systems and avoid other building components.  

Typically, Straus Systems' piping and sheet metal CAD drawings incorporate the hanger and sleeve locations. Currently the firm uses AutoCAD MEP 3D, QuickPen DuctDesigner 3D and QuickPen PipeDesigner 3D AutoCAD-based 3D CAD solutions, Naviswork for clash detection, QuickPen AutoBid Sheetmetal and QuickPen AutoBid Mechanical software, as well as interconnected Vulcan CAM software in its manufacturing plant.

However, field crews typically rely on conventional tools and techniques, such as stationery lasers, string lines and plumb bobs, to locate pipe and duct hangers and sleeves on a jobsite.
Alexander says, “With the advent of BIM, locating points is simply not enough. We have the opportunity to locate positions with greater accuracy and then update the model to reflect as-built conditions.”

To facilitate this speedier, more accurate process, Straus Systems invested in the Trimble MEP layout solution, which includes the Trimble RTS Series Robotic Total Station and the Trimble MEP layout software. 

With the robotic total station, crews download the hanger points from the CAD model into the MEP layout software. Once benchmarks are established, they use the robotic total station to shoot hanger points using the laser. 

"We couldn’t believe the improvements in speed and accuracy," says Alexander. "Using the old methods, a two-person crew could layout 100 hanger points in an 8-hour day. With the robot, we can layout 400 points a day– and we are very accurate. We can measure positions to within one-sixteenth of an inch at 600-feet."

The firm has since demonstrated the benefit of both BIM and robotic technology on two distinctly different projects: a petroleum research complex and a major university lecture hall.

Petroleum complex
A major oil and gas client in the Houston area contracted Straus Systems to design, fabricate and install a new water and steam pipe rack that would be located above an existing rack. The new rack will span approximately 700-feet across existing rooftops to a new facility. 

For the pipe rack, the first step was to determine the exact location of each existing rack support. With the robotic total station, crews were able to collect the existing hanger pipe locations using the robotic total station and upload the data to the 3D CAD model, where designers could position new pipes to fit the given space.

Alexander says, "While it’s difficult to quantify how much quicker we’re capturing data on an existing project or the value we’ve gained from that efficiency, there is no question that we were at least two to three times faster as compared to our previous methods." 

Straus Systems crews found similar advantages during the construction of the Michael J. Cemo Hall at the University of Houston.

On to academia 
This $9 million Michael J. Cemo Hall project includes a 34,000-square-foot building with a 400-seat lecture hall, three 80-seat classrooms and an academic center. 

Straus Systems crews set 396 sleeves for 6-inch round floor diffusers in the lecture hall. The room was round with radius raised tier seating. Sleeves were located under the seats and would eventually receive air diffusers. 

The layout in the concrete formwork phase would have been very time-consuming using conventional means. To complicate the issue, the seating arrangement changed at the last minute causing all the sleeves to be relocated.  The task that would have taken 3 or 4 times as long was accomplished in a day and one-half. Using 3D CAD and deploying the robotic total station with the MEP layout solution made short work of the task. 

Alexander says, "The digital connection we’ve created between the 3D model and the field opens up so many opportunities for us. There are many applications where we can capture existing as-built conditions and import into our 3D model to use in design efforts."
For example, Straus Systems is increasingly called on to help with renovations and rehabilitations and industrial processing plans. In these cases, crews must remove and replace equipment.  

"We can capture existing points, wall penetrations, floor penetrations, piping penetrations, and ductwork positions with the robotic laser, upload the data to our CAD department’s CAD-cave, and design a best-fit solution," explains Alexander. "We foresee many other uses for this type of equipment, including layout of underground work. The digital connection this tool creates between the 3D model and the field is invaluable, opening up new opportunities to improve efficiency and accuracy."