It looks like a section of State Highway 240 (Badlands Loop Road) in the Cedar Pass area of Badlands National Park will be closed for six week as an underground lake was just discovered beneath this stretch of road.
The Badlands Loop Road at Cedar Pass has not been closed yet as park officials and the community are meeting up next week to figure whether to partially close or entirely close the road. My feeling is that they will most likely keep one one lane open while carrying out the works.
There is an alert on the national park service website which says that the Loop Road is under construction at Cedar Pass near Cliff Shelf Trail. There is one lane traffic but the Cliff Shelf Trail and Parking area are closed temporarily.