Part of old Boone Bridge in St. Louis County brought down

ST. LOUIS -- A portion of the westbound span of a 1930s-era St. Louis County bridge was taken down with one of two explosions that will remove the structure on Interstate 64.

The St. Louis Post-Dispatch reported the interstate was closed for about an hour Thursday morning as the Missouri Department of Transportation removed the old Boone Bridge.

Construction on the $111 million Boone Bridge project began in January 2013.

The new eastbound bridge opened to traffic in June, while the 1980s bridge it replaced was rehabbed and opened to westbound traffic in November. A second blast to remove the rest of the old bridge will take place later.