Feature Stories 2020: Smoothing out the Red Line: capstone with community impact

"Has anybody here ever ridden the Red Line? And had a smooth, comfortable ride?"

So begins a senior capstone presentation in Mechanical Engineering, the culmination of a year’s worth of work for a real client, on a real problem, offering a real solution.

The problem starts with a bumpy ride, caused by unevenness in the road bed of the Boston’s Red Line track, ridden by over a quarter of a million people daily. As well as causing passenger discomfort, a bumpy ride means higher wear and tear on cars, lessening their useful lives. Four Mechanical Engineering students worked for the MBTA to design and build a sensor to record these bumps in real time, as the trains are running, to determine exactly where maintenance is needed first.

Being mechanicals, once we were able to hold something physical, we really got to see the light at the end of the tunnel. We started putting in a ton of hours, coming in early and staying late because we wanted to make sure we saw this project to the end and met our deadline.

Like most capstone projects, this involved a multi-step process with research, design, materials choice, fabrication, and testing. Team members had to work within project constraints including technical limits on size, placement, safety, transmission length and wireless data capture. In addition, team members had to consider cost, replication and data collection. As they met and overcame challenges, they had to manage a shifting project schedule.

The team’s research concluded that building a sensor from scratch was the best solution to meet the project requirements. Options were raised, considered, tested, rejected or refined. For the sensor circuitry the team had to dive into electrical engineering. The housing unit went through 8 design changes as 3-D printing revealed correctable flaws.

As time grew short, dynamic testing on Lucy Little Road, Dartmouth substituted for a run over the Red Line track with the sensor measuring and communicating well. The team came in an astounding 93% under budget producing a sensor with a cost just over $50, a quarter of the cheapest commercial version (which did not meet the client specifications). As the project neared completion, the team recommended additional design changes such as adding GPS location data and further stabilizing the sensor in its housing. Next steps are for the MBTA to test the sensor on the Red Line itself.

The Red Line Capstone team is Edward del’Etoile, Kelly Merlo, Nathan Morgado and Michael Sereti. Arghavan Louhghalam, Assistant Professor of Civil and Environmental Engineering, served as project advisor. MBTA clients were Electrical Engineer Michael Walsh and Mechanical Engineer Scott Manning.