Long after rush hour, motorists heading west on I-394 this week have encountered traffic jams between downtown Minneapolis and Hwy. 169. And that will be the case again on Wednesday and Thursday nights.

It's all because new federal regulations require MnDOT to swap out old signs along the MnPASS lane with new ones and install additional signs that comply with new standards outlined in the Manual on Uniform Traffic Control Devices.

What that means is that signs that designate preferential and managed lanes such as MnPASS be marked with the words "Express Lane" and placed at entrances to special lanes reserved for carpools, motorcycles, buses and solo drivers that pay to use them.

The standards also require smaller signs with white backgrounds and the words "HOV 2 +" and "2 OR MORE PERSONS PER VEHICLE" in black letters posted no more than a half-mile apart.

When crews are installing the signs, the carpool lane has been closed and all traffic funneled into the general purpose lanes. That's created some long lines for westbound drivers, including those heading home from Twins games.

The good news is that most of the sign work will be complete by Thursday. But MnDOT says it is running short on steel and will have to come back in October to finish the job.