The snarl-up hit drivers trying to join the A8 at the Chapelhall junction in North Lanarkshire.
It was caused by the closure of the westbound slip road at the nearby Eurocentral junction, which serves one of Scotland’s largest industrial estates.
Traffic at the Chapelhall junction will now be controlled manually by roads officials in an attempt to ease the congestion.
An industry source told The Scotsman: “There is now only one way in and out of Eurocentral, it has caused absolute chaos.
“Some drivers reported queuing for over 90 minutes on McNeil Drive, just trying to go the one mile to the Chapelhall junction.
“It’s not helped by the fact that Newhouse junction and Eurocentral junction are both heavily restricted.
“All traffic being forced on at Chapelhall and long queues were in place from 3 to 8pm on Tuesday.”
The Scottish Government’s Transport Scotland agency, which is in charge of the £500 million M8/M73/M74 upgrade project, said queuing was estimated to have been one to two hours on Tuesday evening, and a reported 30-40 minutes last night.
Officials expect this to reduce further as drivers become familiar with the traffic changes.
A spokesman said: “As with all traffic management schemes, Scottish Roads Partnership (SRP), the contractor for the project, monitors the effectiveness of traffic management once it is installed and implements changes where appropriate.
“To ease congestion, from this evening’s peak, SRP intends to manually control traffic at Chapelhall south roundabout (McNeil Drive) to provide increased priority to those leaving Eurocentral.
“The traffic management is rapidly changing now, and over the coming months, as we move into the final stages of the project.
During this time, we would encourage drivers to pay particular attention to changes in traffic management signs.
“We thank road users for their continued patience as work continues to deliver major road improvements in the area.”