Some kilometers north of Choum on the 704 kilometer long ore railway in Mauretania, the ties are beeing changed, from wooden to new concrete ties, fabricated in the SNIM work in Nouadhibou. A road-rail loader KGT-4RS of the Geismar/France is used by the SNIM workers. The line is beeing upgraded from 26 to 30 ton axle load with new concrete ties and 136 lb heavy rails.