For many families, a traditional Christmas wouldn’t be complete without a model train circling beneath the Christmas tree.

The families of the Lehigh Valley and surrounding areas can delight in this pastime on a grand scale by visiting the holiday open house of model railroads by Explorer Post 101, located on the second floor of the Coplay Borough Municipal Building, Fourth and Center streets.

The display is open weekends noon to 4 p.m. through Jan. 10. Admission is free, but donations are welcome.

On display is an operating vintage Lionel O-scale as well as an American Flyer S-scale train module.

The post is showcasing three large, modular HO-scale layouts, titled the Delaware, Lehigh and Susquehanna Railroad, all of which are built by the Scouts of Explorer Post 101. Layouts are spread out between two rooms and feature more than a dozen operating trains for all to enjoy.

The Delaware, Lehigh and Susquehanna Railroad is a modular display. Each Scout builds a 2-foot-by-4-foot module to what era and theme he wishes to model; the only requirement is that it contain three main tracks set to a specific spacing.

Modules are joined together to form the large operating layouts. This system permits the Scouts to learn about the various facets of the hobby - construction, track laying, wiring, scenery - in a small, manageable way that can still be part of a very large layout.

Since the layout sections can come apart and are transportable, the Scouts display part of the layout annually each November at the First Frost Train Show at Agricultural Hall in Allentown.

The layouts on display represent 40 years of work done by the Scouts. Newly completed scenes this year include an engine terminal, a mountain with trestles and a farm scene.

Families also can enjoy viewing engines and cars modeled after local lines, including ones in the Lehigh Valley, Reading and other Pennsylvania railroads, as well as a module featuring a view of downtown Emmaus.

Explorer Post 101 was organized in 1976 and is one of the oldest posts in the Minsi Trail Council.

Founder Richard Lobach describes the post’s overall goal as “to provide young people an opportunity to enjoy model railroading and enjoy hands-on training in designing, building and operating a large model railroad layout.”

The post is designed for youths between the ages of 14 and 20. Adult advisers also are welcome to join and many youths stay on as adult advisers after turning 21.

The post currently has about six youth members and an equal number of adult advisers.

Youths or adults interested in joining the post should contact Lobach at 610-965-2598 or email Michael Busch at michael.busch@rcn.com.

The post meets regularly 7 to 9 p.m. Thursday nights in the Coplay Municipal Building.