The Walnut Creek Model Railroad Society (WCMRS) operates the Diablo Valley Lines (DVL) model railroad, one of the most mountainous and one of the largest exclusively HO scale model railroads in the United States. This model railroad features standard gauge, narrow gauge, and interurban (overhead electric) freight and trolley lines.

DVL stands among the few model railroads built and intentioned soley for public show and has been featured in magazines and newspapers around the world. 

http://wcmrs.org/