A semitrailer truck caught fire on northbound Interstate 90-39 around 4:25 p.m. Wednesday, leading to a long traffic backup starting in Janesville.
The right northbound lane was closed near the 174 mile marker, north of the Racine Street overpass. Traffic flowed slowly in the left lane.
A state Department of Transportation alert issued at 5:06 p.m. said the lane closure would last one hour. An alert later on Wednesday said the incident was cleared at 6:11 p.m.
Emergency communications indicated the truck was carrying recycled paper and cardboard.
Another DOT alert at 5:09 p.m. said queues exceeded three miles and delays were about 29 minutes.