Editor’s note: TribLive’s Zac Gibson got to ride on Union Pacific’s Big Boy 4014 as the historic steam locomotive made its way through Western Pennsylvania on Saturday.

Big Boy got moving from Wall, where I got on board, just after 4:40 p.m. It passed The Point in Pittsburgh at 5:49 p.m., heading toward a large gathering in Leetsdale.

I was one of eight people in the train’s cab. While only three were in overalls, everyone was wearing earplugs and eye protection at all times.

When stepping into the cab of 4014, the first thing one notices is the temperature change. It’s hot but comfortable, with lots of wind coming in through the open doors and windows.

The furnace, called the firebox, is front-and-center, with the chief locomotive engineer to its right.

A cooler filled with ice water is stocked constantly, as it’s important to keep hydrated during prolonged exposure to the firebox.

The sound of the locomotive and the earplugs made talking difficult, so the crew also used various hand signals to communicate as we moved.

While Big Boy’s average speed would be 30 to 40 mph, it was running between 8 and 17 mph so spectators could take it in. It slows down when heading onto bridges and passing other trains.

There’s almost a “gallop” to the train as it accelerates to 28 to 35 mph.

Although Union Pacific recommended people stay 25 feet away, many spectators were trying to get much closer.

As it traveled west, the densest crowds started on Pittsburgh’s South Side, with lots of people on both sides of the tracks. People were recording the train from cars and bridges and, in one case, from a crane.

As Big Boy crossed into the city, the operating team took time to look out at the cityscape, starting about when they were parallel with UPMC Mercy hospital.

Many people at FNB Stadium were waving flags.

From Ben Avon to Emsworth, spectators became much more mobile, many of them were keeping pace with the front of the train in boats.

The closer we got to Leetsdale, the more people I’m seeing — seems almost as densely populated as the Pittsburgh city stretch.