Ever get caught up in the crowd crossing 12th St. and Polett Walk? It was inspiration for one Senior Design team to build an energy-harvesting sidewalk that does double-duty as snow and ice removal, and a traffic signal.
While walking to class one day, Jake Faro found himself in a situation where we've all undoubtedly been at one time or another: the wave of pedestrian traffic washing over 12th Street near the Bell Tower—particularly between classes.
"We calculated that about 2,200 students, faculty and staff move through the intersection every hour," noted his teammate William Campbell.
This crystalized a discussion around the team's Senior Design project. Faro and Campbell, along with Nour Almarshoud (all Civil Engineering majors) huddled with teammate Anthony Calfapietra (ECE) to plan and build.
The project evolved from a previous team's idea of building an energy harvesting walkway. This version would keep the energy harvesting piece, while adding-in temperature control to melt snow or ice in the winter. And about those crowds?
The group married the previous team's energy harvesting idea with similar technology used in Japan's subway system, adapting it for a smaller-scale use on campus.
"All of the energy from the solar panels and the piezoelectric discs will be stored in a battery that can run everything," Calfapietra said. "People who walk over the intersection, that compression will generate energy to run the heating element, but also traffic lights running around the panels for pedestrians, as well as lights for vehicle traffic."
The team estimated approximately 30,000 PSI was the compressive strength "sweet spot" before the concrete would fail, which is a concern they estimate can be worked out with more malleable materials.
"We want to get resistance across the surface that we're looking for, but also the strength," Campbell said.
Ideally, on a snowy day, those 2,200 people could cross a cleared walkway that signals go, yield and stop lights below, with similar lighting for cars, all powered by their feet.
Even so, the project wasn't without its rough spots.
"We decided to use an electric concrete composite (for the sidewalk piece)," Faro said. It's made up of graphite, carbon fiber and steel shavings, to heat up during the winter. On top would lay a "really nice piece of laminated glass" from the previous team.
One day, Calfapietra stopped by the lab to pick up the glass and take with him to work with over the summer.
"When I picked it up, I noticed it had been dropped. So the top layer was cracked. I had the bright idea to try and chisel off the top layer of glass. We tried to chisel off the top layer and then the second layer broke," he said, pointing to a residual glass shard.
Though the team is relying on a one-inch piece of acrylic as a stand-in, they are confident the piece will be ready for review and, possibly, to pitch for commercial application at a later date, once they can order the correct laminated glass again. They've even been encouraged to pursue small business incubators to pitch the idea.
"Right now, we're just focusing on finishing and graduating," they laughed.
Follow along our coverage of this semester's Senior Design teams on social media with #TUSeniorDesign2017, and stop by the poster presentations on December 9.