It is also the name of the furnace near Braddock. I think they liked to name things after women. Look at the streets on the Southside.
From a story about the Eliza furnace in Pittsburgh, and another furnace named Ann: “When Ann was built in 1899, two existing furnaces on the site were each called Eliza, named after women in the families of steel barons Benjamin Franklin Jones and James Laughlin, the company’s founders. As a new furnace, Ann didn’t have a name. She was simply called P3, for Pittsburgh 3, a designation she would carry until 1966. After being rebuilt that year, she was christened Ann, in honor of a relative of one of the company executives.”
I think the J&L furnaces were named after women in the Jones and/or Laughlin family. The Eliza furnace and associated buildings stretched up and down Second Avenue near the Hot Metal bridge, thus the name of the trail. Who knows who the other “Eliza furnace” was named after?