If you've ever ridden a subway, you've probably experienced a bump in the tracks that could send your coffee onto another rider.
George Lederman, doctoral candidate at Carnegie Mellon University, wants to fix that, though you may never notice his work.
Piezoelectric sensors fixed to train cars with electrical tape are at the heart of Lederman's monitoring equipment. They measure changes in pressure, acceleration, temperature, strain and force by converting these changes into an electrical charge.
“The car vibrates and the amplitude of that signal corresponds to the amount of vibration the car senses,” said Port Authority engineer Dave Kramer, who’s worked closely with Lederman.
Each car bears one sensor on its underbelly and two more locked in the cabinets near the driver’s booth. They communicate with a GPS antenna atop the vehicle through tiny computers, so when a spike in the data pops up, Lederman can determine the coordinates of bumps along the track.
Take Port Authority's Beechview section, he said. Lederman’s monitors detected a bump, so inspectors took a look. It turned out to be a bolt embedded into the railway that had likely rolled into the track from a shop dumpster outside a nearby auto parts store.
“And as cars ran over it, they would hit it,” Kramer said. “This is a case where his equipment found this before it was seen. You know, eventually one of our inspectors would have seen it."
Port Authority workers visually inspect the tracks four times a month, twice by walking the rail and twice by riding. Lederman said the data from the sensors gives them another tool.
"This technology works, and it can be used to identify areas that need looked at before they become a problem," Kramer said. "It is an asset to our ongoing inspection program.”
Lederman's work could have broader effects. The U.S. House of Representatives just approved more than $300 billion in spending to help rehabilitate the nation's aging transportation infrastructure, far short of the $478 billion sought by President Barack Obama.
"The infrastructure’s aging, so we need more and more funding, but actually the funding pool from the federal government is actually decreasing, so there is a growing gap in terms of what we can invest in our infrastructure," Lederman said.
Technological solutions could help existing federal spending go further, Lederman said. In Milan, similar technology has been used to detect waves in rails that led to noise complaints. Researchers at the Massachusetts Institute of Technology are using it to map potholes from sensors mounted on cars.
The sensors are much cheaper and more accurate than they once were, Lederman said.
“I like that they’re trying to figure out where these bumps are so it’s a lot smoother,” said Point Park University student Jessica O’Shell, who commutes to and from the South Hills Village. “So you don’t have to stop, change tracks, because that adds about five to ten minutes to my trip. Whenever I come here I want to go straight down. I don’t want to be bothered with all this.”
In this week’s Tech Report calendar:
The Out in Science, Technology, Engineering, and Mathematics, or oSTEM, Conference begins November 13 at Carnegie Mellon University to recruit and support STEM-driven, LGBT+ students.
Sit With Me, a campaign from the National Center for Women in Technology, will host a local RedChairPgh event Nov. 19 to provide area companies with resources to encourage women’s employment in tech careers.