“Everything’s up-to-date in Kansas City” goes the Broadway tune from “Oklahoma!” In terms of de-icing and snow-melting sidewalks in wintry cities, Kansas City, Mo., is beyond up-to-date. As snow fell on city streets in December 2019, platforms along the Prospect Max bus route were clear and dry, thanks to conductive concrete. It is a mixture containing electrically conductive components in a regular concrete and an automatic low-voltage system that turns on when moisture is detected in the air and the outside temperature drops below 38°F. This emerging technology is being used to de-ice sidewalks, parking garages, highway bridges and airport runways in central and eastern parts of the United States.
Conductive concrete is the brainchild of Christopher Tuan, professor of civil engineering at the University of Nebraska—Lincoln. He was granted the patent for the technology in 2004.
Tuan’s experience with the technology began when he was working as a contractor for the U.S. Air Force in the mid-1990s during the Bosnian war in Eastern Europe.
“There were some heavy carriers in use,” Tuan said. “When landing on a ship during icy conditions, some of the transporters [aircraft used to transport troops or military equipment] skidded, so they wanted to find a way to de-ice the runways. At that same time, I was working on steel-fiber-reinforced concrete and thought of the idea to run electricity through the fibrous concrete for the purpose of de-icing.”
After Tuan traded defense work for academia, he proposed his system of conductive concrete to the Nebraska Department of Transportation.
“They thought it was a great idea and worth exploring,” he said.
Tuan then worked as a consultant on the world’s first implementation using conductive concrete. The project’s goal was to heat the deck of the three-span Roca Spur Bridge above Salt Creek at Roca, Neb., a 150-foot-long-by-36-foot-wide bridge near Highway 77 South. Bridge construction was completed in November 2002, while the heated deck control used to de-ice the deck of the bridge system with conductive concrete was completed in 2003.
Fast-forward to 2021. A recent conductive concrete project is part of Kansas City’s recently completed RideKC bus rapid transit line, called Prospect Max. It is a 10-mile route along Prospect Avenue between downtown Kansas City and 75th Street. Boarding platforms containing conductive concrete now melt snow and ice at 16 high-ridership stations along the route.
Prospect Max is a $56 million transportation investment in one of the highest ridership corridors in the region. The investment is made possible by local and federal funding that has made the corridor safer and more inviting for pedestrians, transit customers and bike and scooter riders.
One stop along 11th Street—the western route through town—is Petticoat Lane, the location of the city’s clothing retail center and Kansas City’s first department stores. The name Petticoat Lane is a reference to the mostly female shoppers at those stores, who hopped on streetcars to get there. Today’s shoppers board buses along that Prospect Max route, one made safer in foul weather by the conductive concrete technology.
“The 11-story building that housed the Harzfeld’s Department Store, which opened in November 1913 and offered the finest clothing in the city, still stands on 11th and Main,” said Brad Wolf, Kansas City’s historic preservation officer.
The project has an altruistic focus, since RideKC’s priority is to return economic and community value to the region through transit-oriented development. Planners want to enhance places where people are, such as bus stops, and create areas where people want to be. Building off the success of other bus routes—Main Max and Troost Max—Prospect Max offers BRT amenities such as shelter protection, interactive smart kiosks with real-time bus arrival information, enhanced lighting, free Wi-Fi at stops and on buses, frequent service, traffic signal priority at stoplights and fewer stops for faster service.
The conductive concrete de-ices paved areas without chemicals. The stations are also designed to blend in with the downtown streetscape, making it easier for pedestrians to navigate the sidewalks.
Because the electrical contractors on the project—Max Electric Inc., Grandview, Mo.; Kansas City, Mo.-based Black & McDonald Electric and Alpha Energy and Electric Inc.; and Capital Electric Construction Co. Inc., Kansas City, Kan.—were unfamiliar with the conductive concrete technology, they faced a steep learning curve during installation and all worked closely with Tuan.
“It wasn’t normal that you do electrical and pour concrete on it,” said Jackson Nzioki, project engineer at Alpha Electric. “For us, it was a first-time experience and a different experience. We usually put in conduits. We thought about safety and I was thinking, ‘What am I doing? Is this safe? People are going to be here. Will someone be shocked?’
“We tested before the pour to see if it worked as Dr. Tuan guided us in what we were doing until he approved the results. We kept on asking questions. He kept on answering them.
“What was most challenging was training and bringing all the subcontractors together,” Nzioki said. “When anything needed to be done, all the trades—including concrete and electrical contractors—had to keep the controls straight to make sure everything went well.
“It was a challenge to have multiple contractors doing the work. Let’s say we were troubleshooting. Usually you say to yourself: ‘I’m the EC. I can do this.’ But on this project, we had to work with everybody from the general contractor to the control guy,” he said.
According to Jerry Prochko, Black & McDonald’s division manager, “The most challenging task related to the conductive concrete heating and de-icing was finishing the design work and installing something new for the first time since the original design was not complete. It was more like a design-build project. Balancing the load on the transformers, for example, and issues with the load division or sharing were our only electrical issue. What I learned is that when building a warming system, it is important to continually pay attention to details. It is a new system, and from lessons learned, we have a game plan for the next time we do this type of project, which definitely needs a different approach.
“About electrical work, I learned that everything is possible if you put your mind to it. A year ago, I couldn’t have imagined this entire project, something out there for people to use to make their lives easier,” he said.
Tuan offers these tips to electrical contractors for a successful implementation of a conductive-concrete, snow-melt system.
- Coordinate with the concrete contractor to finish the electrical work before casting conductive concrete.
- Remember that conductive concrete is the heating element when the system is energized.
- Pay attention to details on the construction drawings and construction notes.
- Ask questions when you have any doubts about the technology.
- Use the materials and products listed in the material specifications, which have been validated for good performance.