Fireworks barges head to Charles River

(John Tlumacki/Globe Staff/file 2008)

Last July, workers prepared to load fireworks into shells on barges in the Charles River.

By Michaela Stanelun, Globe Correspondent

Four barges heavy with sand and empty mortar tubes will be nudged into position today on the Charles River as preparations enter the final stage for the Fourth of July fireworks spectacular.

Planning for the nationally televised event this weekend on the Esplanade began in winter and required some 3,000 hours of intensive work, said Steve MacDonald, a spokesman for Boston 4 Productions. The fireworks display will include over 25,000 pounds of pyrotechnics fired in 12,000 shells. To synchronize the show to music, hundreds of mortar tubes will be connected to computers with 5 miles of wires.

"It takes 11 days to set up the show," MacDonald said, "and it’s gone in 21 minutes."