One look at the work done by the North Shore Model Railroad Club immediately dispels any misunderstanding about the complexity of the pastime. The club's train layout measures 40 feet by 90 feet, uses more than five scale miles of track, and simulates a train line running from Fredericksburg through the mountains of West Virginia, then splitting, with one leg going to Chicago and the other to Kansas City, Mo.

"The scenery and the buildings look like the real thing," said Rockwell. "And we have as much stuff backstage that's not being displayed as onstage. So you can run behind the scenes and put a train onto the track and it'll show up through the mouth of a tunnel or under a hill as it appears onstage."

At the railroad club, the running of trains is no arbitrary matter. "There's an established schedule of what trains run when and what they carry," Rockwell said. "We're trying to simulate a transportation system."

The club, which meets in Wakefield, holds its business meetings the first Thursday of every month. Trains are operated the second Thursday of the month, as well as the following Saturday. For times and information, call (781) 245-4742.

MIT's model train club first met in 1948 and has been going strong every since. During its 50 years of operation the club developed an elaborate layout. By the mid-1990s, the layout measured 25 feet by 100 feet, and included about five scale miles of track and 200 railway cars.

Though the layout was recently dismantled because the club moved to a new location (the MIT Museum on Massachusetts Avenue), the group is creating a layout that will be capable of running up to 16 trains simultaneously.

"Everything is being automated," said Saenz-Otero. "Currently, we have 46 turnout switches in the track, which are being computer controlled."

"We're going to have it so that the engineer running the train can actually see a signal, like a stoplight, telling him to 'go,' 'stop' or 'slow down.' We're the only club that has that."

While club membership is limited to MIT students and alumni, Saenz-Otero said the group welcomes participation by "anyone who wants to come." The group meets 5 p.m. to 1 a.m. Saturdays and 7 to 10 p.m. Wednesdays.

Train buffs commuting through South Station this holiday season will be greeted by the return of the station's annual holiday train exhibit on display in the main concourse from Dec. 3 through Jan. 5.

This year's exhibit will feature two electrical g-scale trains, running through festively lighted towns and tunnels and across snow-covered bridges. (The letter in the scale description refers to the ratio of the model train size as compared to the full-size train).

Designed by Ralph Williams Landscape Design in Harvard, the display fills a 16-by-20-foot platform.

"People come by the station with their kids especially to see the display," said South Station spokesman Daniel Dombak. "It's a very popular tradition."

Another great place to take in trains and get into the seasonal spirit is the Berkshire Scenic Railway Museum in the historic Lenox railroad station. Though the museum is closed for the winter, it will be open Dec. 19-20, from 10 a.m. to 4 p.m., for its annual holiday display.

The museum features an eight-panel exhibit on railroad history, as well as three model train sets (g-scale, n-scale and HO-scale) that run through a diorama of Stockbridge, Lee and Lenox. A train-themed gift shop will also be up and running for the weekend.

Another big draw is the museum's ride aboard a 1920s coach pulled by a 1950 GE locomotive. Santa will be on hand to ride the rails and pass out candy to train lovers young and old. For information, call (413) 637-2210.

Rail enthusiasts headed toward Connecticut will want to make a stop at the Danbury Railway Museum in the refurbished 1903 Danbury rail station. The museum houses railway artifacts, including tools, engine headlights and bells from the steam era.

The museum and its adjacent railyard also house several coaches, cabooses and engines, several of which have been restored to their original turn-of-the-century condition. Cost is $3 for adults, $2 for kids 2 to 15. Hours, through Dec. 31, are Wednesday through Saturday, 10 a.m. to 4 p.m., and Sunday, noon to 4 p.m.

Also worth visiting is the Maine Narrow Gauge Railroad Co. & Museum in Portland, Maine, which features little-known coaches from the long-defunct 2-foot gauge railway that once ran in Maine and Massachusetts. Call (207) 828-0814.