I-75 downriver closure

OK, southbound lanes are closed between Springwells and Northline for badly-needed rehab, incl Rouge Br. So why, if northbound lanes are supposedly functioning as normal, are various northbound entrance ramps, such as at Dix and Fort streets, blocked by orange barrels?

Just speculation, but I know they're doing major and minor repair on many of the bridges in the area, so could be something to do with that.

To p-rovide parking places for the construction workers.