I was in Mauritania in June and the papers were full of it. Work seemingly started in mid July and should be finished in 24 months, Inshallah. There are no Mauritanian construction companies involved so this should be possible.
The route should leave the border at Geurgerat, go south east until it meets the railway and then stay east of the National Park meeting up with the coast somewhere between Nouamghar and Toulit.
May Allah smile upon them so that the sooner they are finished the sooner we dont have to kick and push our crappy old Mercedes through that piece of shit piste.