A Big Boy of a bygone era eased into Houston Wednesday, giving train fans a chance, albeit brief, to check out the world’s largest steam engine.

“It is definitely something to see,” said Tracy Hobdy, executive director of the Rosenberg Railroad Museum. “It is just generating a lot of excitement.”

The museum held a viewing party Wednesday afternoon for the passing of Union Pacific locomotive 4014, the only working 4-8-8-4 “Big Boy” in operation.

Twenty-five Big Boys were made to make long-haul routes through western states. They are notable for their size and unique setup with four wheels in a front arrangement, two segments of eight pulling wheels and four rear wheels to support the rear of the locomotive — hence the 4-8-8-4 moniker. Also unique is the hinged style of the bodies of the Big Boy that allow the massive machine to negotiate curves on the rails.

Seven other Big Boys still exist, but are not operational, including one at the Museum of the American Railroad in Frisco.

Big Boy 4014 is on a tour of the UP territory to mark the 150th anniversary of the transcontinental railroad.

The train will be available for viewing Thursday from 9 a.m. to 3 p.m. at the Amtrak depot, 902 Washington, in downtown Houston. It is free to check out the train and the accompanying railcar that acts as a rolling Union Pacific museum.

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Kurt Wilson, 81, will be there for a close-up look even though he also was scouting watching locations for Wednesday. A train buff, Wilson called it a rare chance for fans to see history.

“For those of us who remember traveling by train, when that’s what you did, it brings back a lot of memories to see these old trains still running,” Wilson said. “They just don’t make them like that anymore.”

Wilson sighed. Asked if not “making them like that anymore” makes him sad, he quickly rebuffed the suggestion.

“Not at all,” he said. “I’m a lot like that old train. If people take care of me, I will live forever.”

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How big of a deal is Big boy in train circles? People were talking about pulling their kids out of school early to get to Rosenberg in time, Hobdy said.

“There are a lot of rail fans in this area,” Hobdy said, noting for many people the railroads were a part of growing up in the region.

“Rosenberg is a railroad town and is here because of the railroad,” she said.

The switch tower at the railroad depot in Rosenberg was operational until 2003.

“There is still a lot of nostalgia about it,” Hobdy said.

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Many other towns ringing Houston, from Alvin to Tomball, owe their early development and growth to the railroads. Houston famously was turned into an economic hub because it was where 17 railroads met the sea. The city’s seal even features a steam locomotive — though it hardly measures up to Big Boy.

The massive engines were built to handle steep terrain, capable of carrying goods in and out of the mountains. Big Boys weighed 600 tons, generating almost 6,300 horsepower, with a top speed of 70 mph.

Do not expect it to hit those kinds of speeds through Bellaire, however. The organizers of the trip want people to get a good look at the train.

Big Boy is scheduled to depart Houston at 10 a.m. Friday, headed northwest to College Station. The schedule has it stopping at the Elm Street railroad crossing in Spring for 15 minutes at 11:15 a.m. and at South Railroad Street in Navasota from 1:15 p.m. to 1:45 p.m.

dug.begley@chron.com