Drivers who use westbound Interstate 694 through Little Canada and Arden Hills have been waiting six months for this news: Work on adding a third lane between Rice Street and Lexington Avenue is finally complete.

The Minnesota Department of Transportation opened the newly added lane Friday afternoon, barely completing construction before the season’s first snowfall. But call it a short reprieve, as the segment will once again go back down to two lanes this spring when construction on a third eastbound lane begins.

“We realize that some drivers will be annoyed after they will have had three lanes for six months,” said MnDOT spokesman Kent Barnard. “We promise that we will get the lanes open as soon as possible.”

The new lane was added as part of the $42 million Enhance 694 project, intended to improve traffic flow along the four-mile stretch that’s often clogged during rush hours.

The segment is the 10th worst corridor in terms of congestion and delays in the metro area and 320th worst in the nation, according to the 2015 Traffic Scorecard put out by the Seattle-based global traffic-tracking company INRIX.

When construction began last spring, MnDOT split the two westbound lanes at Rice Street. Motorists who chose the lane that veered right had access to on and off ramps between Rice Street and Lexington Avenue. Drivers who picked the lane that veered left had no ability to get off the freeway until reaching I-35W. The new lane was built in between the two traffic lanes that were left open.

To keep two westbound lanes open during construction, two eastbound lanes were shifted to the right to make room for a temporary westbound lane that carried through traffic. This week, MnDOT will begin removing the temporary westbound lane and the concrete barriers that separated it from eastbound traffic. The eastbound traffic lanes will revert to their original configuration.

Drivers may encounter temporary lane closures in either direction through early December as crews install lighting and finish cleanup efforts, Barnard said.

In April, or whenever the weather turns nice again, MnDOT will employ the seldom-used setup again when it adds a third eastbound lane. At that time, one westbound lane will be used to handle eastbound traffic, leaving two westbound lanes open. Eastbound traffic will be split into two lanes at the Snelling Avenue interchange. Drivers will have to pick a lane allowing access to local streets or one that won’t allow drivers to get off the freeway between Snelling Avenue and I-35E.