Photo: Traffic flowing smoothly this morning on SB I-75 at site of the old Hopple Street overpass collapse @ldufourpic.twitter.com/Ic12flAmwT

— Enquirer (@Enquirer) January 21, 2015

A section of southbound Interstate 75 in Cincinnati has reopened, following a bridge collapse late Monday evening resulting in its closure.

The area around Exit 4 was closed for about 24 hours when part of the old Hopple Street overpass fell into the roadway. It was undergoing demolition when the incident happened, killing one construction worker and slightly injuring a trucker who ran into the debris as it fell into the roadway below.

Investigations are being conducted to determine the cause of the collapse, but initial indications are that it was not due to any structural problems, according to published reports.

The Cincinnati Enquirer newspaper reports experts it talked with say the collapse could have been triggered by the earlier removal of another section of the overpass, which may have weakened the overall structure.

Estimates are between 150,000 to as many as 200,000 vehicles pass through this part of I-75 every day.