Workers at the Oregon Zoo in Portland always knew that patrons loved their trains. The retro-modern Zooliner and the red-and-green Centennial steam locomotive, which run on a narrow 30-inch-gauge track and have been shuttling visitors around the 64-acre zoo since the late 1950s, are a major draw.

It wasn’t clear just how beloved the trains were, though, until they went offline for more than a year.

“We got a surprising number of folks—members and other guests—who had grown up with the trains, and were very sad that they were gone,” says Mark Loigman, the zoo’s facilities manager.

The two locomotives weren’t just out of commission—they left the zoo premises entirely. For the first time since their installations in 1958 and ’59, respectively, when the zoo moved to its current location, the Zooliner and Centennial received a total overhaul.

Both had been maintained with what Loigman describes as “Band-Aid-type work” over the years, based on the zoo’s limited resources for in-house maintenance. In June 2014, they were transported by custom-made flatbed truck to the Pacific Truck Centers in Ridgefield, Washington, for a total renovation and, in the case of the diesel-powered Zooliner, an energy-efficient retrofit.

“They had to go in and start from scratch for a lot of the body work for the Zooliner,” says Loigman, explaining how the crew found sheet metal panels that looked like Swiss cheese. The Zooliner also received a modern, low-emission diesel engine, while the Centennial got updated plumbing and a fresh paint job,as well as a new tender car (the car that holds a steam engine’s fuel), a steel facsimile of its wood-framed original.

A new railway route was also a component of the train overhaul. An elevated track reaching a maximum height of 50 feet will eventually overlook an Elephant Lands exhibit that is currently under construction, giving visitors a view they can’t see from any other vantage point. “It’s really kind of a unique opportunity,” says Loigman of the chance to relocate the tracks during the trains’ absence.

The Zooliner and Centennial officially began operation again on November 28, 2014, just in time for the annual ZooLights holiday celebration. The anticipation for their return was clear; some patrons waited hours for an eight-minute ride. “We had the best ZooLights we’ve ever had, and the best train ridership we’ve ever had,” says Loigman. “I think there was that pent-up sort of demand, you know, for folks coming back to really see them again.”

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