I was in Dar a few months ago. Didn't do that road, but talked with other travelers. Bridge is out, but there's a ferry, except it is expensive (at least for 4-wheel vehicles).
They are building a new bridge crossing on that river a couple hundred kilometers to the west. The roadway isn't great at present - takes a day to go west, and another day to get back east to the coast road, but there's a passable route if you want (as long as it isn't raining, and then it may not be passable).
Chiang Mai, Thailand