Process Solutions and SASCO Replace Safeco Field Roof Control System

Process Solutions and SASCO Replace Safeco Field Roof Control System

If you attended a Mariners game during the 2018 season on a rainy Seattle day, you were likely thankful for the closed stadium roof overhead that kept you dry. What you may not have known, however, is that the control system operating the roof was recently overhauled with a new, modern control system produced by a partnership between Process Solutions and SASCO.

The Problem

The existing roof control system, which had been in place since the stadium opened in 1999, was using obsolete VFD’s, as well as an antiquated PLC system that was introduced to the market over 30 years ago. Furthermore, both the drives and PLC controllers were no longer supported by suppliers or commercially available.

With the obsolete control system components beginning to fail, the stadium was forced to either pay for costly repairs or search for replacements on the used market. With the Seattle Mariners opening day only five months away, it was decided that the best solution was to build a new, modern control system to have the roof operable in time for the start of the 2018 Baseball season.

The Solution

Process Solutions and SASCO partnered together to design and build a modern control system to operate the 22-million-pound roof. The new system consists of eight back panels, each housing a single 200HP DC drive, a fully automated, redundant PLC back panel, an operator control station back panel with remote I/O racks, and a manual PLC panel. Additionally, each of the roof’s wheelsets are equipped with a sill panel, which contains safety controllers and remote auto racks. The sill panels are used to monitor the wheelsets and provide diagnostics on the roof’s operation. Process Solutions also improved upon the system’s skew control technology, which lessens the stress placed on the mechanical structures of the roof during transit.

Altogether, the new system is comprised of eighteen new back panels and one controls cabinet combining for eleven PLC’s with 1200 total I/O points, 1600HP worth of drives, and over 55,000 feet of wire. The system also includes more safety features and added redundancy for more reliable roof operations.

Drive Control Back Panels

Four of the eight new, 200HP drive back panels housed in mild steel enclosures.

Drive Control Back Panels

The eight 200hp drive back panels are lined up in a bank of mild steel enclosures.

Fully automated, redundant PLC back panel. 


Manual PLC panel installed alongside the drive back panels. This panel has three I/O racks with 440 I/O points.

This back panel is housed in the roof operator control station. The back panel consists of a remote I/O rack and ethernet switches.

One of the sill panels located near the roof wheelsets. These panels contain safety controllers, as well as remote auto racks, and provide diagnostics on the roof's operation.

The view looking down the tracks used by the roof's wheelset "trucks" to travel back and forth.

One of the eight roof wheelset "trucks."


Part of what made this project successful was Process Solutions’ partnership with SASCO. While Process Solutions was responsible for the design and build of the new control system, SASCO worked on the demolition and removal of the old system. SASCO was also responsible for installing the new control system at Safeco Field, wiring the panels to the equipment, conducting system power-up, and providing troubleshooting assistance.

SASCO has been involved in numerous projects at Safeco Field with past projects including the installation of the 11,425 square-foot jumbotron, which is the largest in the MLB, as well as the installation of security camera conduit, lighting in the Mariner Moose Den, power for kitchen equipment and various kiosks, the ribbon display boards around the field, and power for the security metal detectors.

Why Process Solutions was Chosen for the Project

Process Solutions’ and SASCO’s staff flexibility and work capacities played an important role in securing the Safeco Field Roof Controls project. With only 5 months before the start of the 2018 MLB season, Process Solutions and SASCO were able to rapidly mobilize a team of engineers, shop technicians, and electricians to work on the project without having to delay or impact the progress of other ongoing projects.

To further save time, Process Solutions built pre-assembled wiring harnesses, along with pre-fabricated back panels, creating a plug-and-play style assembly process.

Finally, Process Solutions’ and SASCO’s demonstrable expertise and knowledge of the existing Safeco Field roof control system, as well as comparable systems from the same era also helped secure the project.

The Challenges we Faced

The Safeco Field project presented Process Solutions and SASCO with unique challenges that needed to be overcome. The main challenge, however, was complying with a tight schedule to meet the needs of the Seattle Mariners opening night and the Stadium maintenance crews.

Another challenge faced during the project was maintaining as much internal infrastructure at the stadium as possible. This included existing field wiring and equipment placement, which meant Process Solutions needed to lay out the new control system’s back panels in a specific way to mesh with the internal structures.

In the end, Process Solutions and SASCO were able to meet all deadlines and overcome each of the challenges faced during the project. This resulted in the delivery of a turnkey control system to Safeco Field that will be supported for many years to come.

About Process Solutions, Inc.

Located near Seattle Washington, Process Solutions is the Northwest’s largest control systems integrator. With 30+ years in business and over 100 engineers and technicians on staff, Process Solutions has the knowledge, experience, and capacity to take on almost any automation project. Process Solutions provides a wide range of automation services, including electrical control panels, PLC and HMI programming, Industrial and collaborative robots, energy management and refrigeration systems, and SCADA and IIOT software. For more information, please visit  

For more information about SASCO and the products and services they offer, please visit

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We provide numerous remote and on-site services to our customers, including software upgrades, troubleshooting, hardware replacement, and feature additions. Our staff size provides us flexibility to quickly respond to standard time frames and emergency service.


Process Solutions provides installation services, as well as system start-ups. Our staff will travel anywhere in the world to help you get your system up and running. We start up hundreds of systems per year, and our licensed electricians on staff can pull permits as needed.


Our Engineering and CAD department can create a wide range of documents, including functional specifications, software design documents, test manuals, O&M manuals, P&ID, system drawings, and network drawings. Drawings for FDA level documents are a particular specialty.


Process Solutions software designers are equipped to handle any size job. We structure our program code to be easily read by both customers and engineers, making support and system upgrades fast and easy.


Process Solutions builds over 3,000 panels per year. Our high-volume model makes our technicians experts in the field and provides our customers with an industry leading experience. Efficient manufacturing practices, mixed with automated manufacturing equipment, allows for quick and consistent job completion.


Creation of custom designs for new and legacy systems. All drawings are template based using automatic CAD macros. Our techniques create an efficient design process with recognizable and easy to understand drawings.