MILWAUKEE -- It's just the kind of news you don't need to hear on a busy traffic Friday.

A semi-trailer jackknifed on the Mitchell Interchange Friday, spilling 48,000 pounds on the roadway, causing traffic backups and road closures that have plagued the Milwaukee-area freeway system for miles.

According to Milwaukee County Sheriff's Office, the Jackknifed semi and concrete debris caused the closure of all lanes from the north to the west in the Mitchell Interchange, along with the southbound Layton off-ramp.