The project, which was approved in 2012, involves completing track-doubling on the 142km line from Settat, 84km south of Casablanca, to Sidi Ghanem near Marrakech. Track doubling has already completed on the Skhour - Benguérir and Sidi Ghanem - Marrakesh sections of the line, a total distance of 40km.

Ridership on the route has increased by 20% between 2010 and 2014,and passenger numbers are forecast to continue rising from around 4.5 million per year to 7.4 million by the time the project is completed in 2020.

The $US402m modernisation project, which also includes track and electrification renewals, will reduce journey times for passenger trains from 3h 37min to 2h 59min and increase capacity from 24 to 36 trains per day. The upgrading of the line will increase freight capacity from five trains per day to 12.

In 2010 the AfDB provided a $US 396m loan to construct a third track on the 148km Kenitra -Rabat - Casablanca section of the Tangiers - Marrakech corridor.