Alabama officials are considering putting up fog-warning signals after a series of wrecks Dec. 7 on the I-65 bridges crossing the Tennessee River, The Decatur Daily reported.

State troopers said dense fog and ice on the bridges - which lie between Decatur and Huntsville, AL, in the northern part of the state - led to the wrecks, which took place between 6 and 8:30 a.m.

The state Transportation Department is investigating the accidents, the largest of which was a 17-vehicle, chain-reaction crash on the southbound bridge, the newspaper reported. Troopers said 15 cars and pickups and two tractor-trailers were involved in that wreck.

Seven cars were involved in four separate accidents on the northbound bridge.

"I haven't gone back and reviewed the history of that bridge, but if fog is a problem in that area, then we should probably consider putting some kind of fog-detection and -warning system there," Assistant Transportation Director Don Vaughn told the newspaper.

Five serious accidents have taken place on the I-65 river bridges this year. Nearly all of the wrecks were during bad weather.