The Arizona Big Train Operators come chugging down the track to Mesa Main Library, 64 E. First St., from July 30 to Aug. 4 in a 500-square-foot, model-trains exhibit of G-scale (garden size) railroads with passing tracks, historical dioramas, bridges and villages.

The free exhibit is open 10 a.m.-7:30 p.m. Monday, July 30, through Thursday, Aug. 2; 10 a.m.-4:30 p.m. Friday, Aug. 3; and 10 a.m.-2 p.m. Saturday, Aug. 4.

Free rides for adults and children will be available aboard the Mesa Library Express trackless train 10:30 a.m.-noon and 2-4 p.m. on Friday, Aug. 3, and 10 a.m.-1 p.m. on Saturday, Aug. 4. Final pickups will be 30 minutes before closing time.

Two sets of four tickets for a train ride at McCormick-Stillman Railroad Park in Scottsdale will be raffled each day by Arizona Big Train Operators. A grand-prize at the end of the exhibit for two passes to the Grand Canyon Railway also will be raffled.

For more information visit mesalibrary.org. For more information on the Arizona Big Train Operators visit azbigtrains.org.