But it was painfully new to Tom Keeley, a reluctant first-time observer. He was there to honor his son Mark, a Philadelphia Gas Works employee who died, at age 19, when a gas main exploded.
For Keeley, there was mainly silence.
Another tough day to get through, like all the others. "I'm crushed," he said, and then fell silent. His son had followed Keeley, and Keeley's father, into PGW. That weighs hard on Keeley - "absolutely" - as if, somehow, he were to blame for his son's death, instead of a faulty furnace in an office building.
This year's list of 170 people who died on the job in 2010 in Pennsylvania, New Jersey, and Delaware fatalities includes someone kicked by an elephant, a farmer knocked over by a cow, a lunch-truck owner run over as he stood next to his truck, and a race-car driver who died when the car's parachute failed to deploy to slow the car.
The youngest worker was 12. Luke Hahn died July 5 while working with his father in Northampton County. The boy backed a truck into a propane valve, causing an explosion.
As is usual, most workplace fatalities occurred in construction. Typical would be the deaths of James Berry, 35, who died a year ago Friday in Berwick when a trench collapsed, and Angel Ramiro Loja, 38, who died Oct. 25 in Havertown when he fell 20 feet from a roof.
Workplace homicides claimed the lives of another large group.
Among those who died were William Glatz, 67, who was shot Oct. 21 during a robbery at his jewelry store, William Glatz Jewelers, in Philadelphia, and Nuan Mo, 53, who was stabbed during a robbery at Family's Laundry in Philadelphia on Aug. 11.