THE POLAR EXPRESS: Ethan Post, 3, of Sidney, watches a smoking locomotive go past him Friday afternoon outside the Maine State Museum in Augusta. The Great Falls Model Railroad Club of Auburn and Augusta’s Maine 3-Railers will display their trains in the Cultural Building atrium again from 10 a.m. to 3 p.m. today. Museum admission is free. It is located at 230 State St., beside the State House.