Following on from the success of the first high-speed railway line in Africa, the Tangier–Kenitra line (200 km), Morocco is pursuing plans to continue to develop its network of high-speed lines. In this perspective, ONCF (the Moroccan national railway company) has appointed Egis as general consultant for external control on the HSL from Kenitra to Marrakesh. After Kenitra-Tangier, Morocco now wishes to extend its line to Marrakesh with 450 km of brand-new tracks. This project, an element of the Rail Morocco 2040 plan, constitutes a strategically important link in the continued development of the high-speed network, and will facilitate connections between major cities of the Kingdom, thereby offering high-quality service to rail network passengers.Consequently, in anticipation of the considerable workload arising from the coordination of these designs and their importance for the development of the rail network, ONCF appointed Egis as general consultant.Each of these design packages must take into account the functional challenges specific to their geographical perimeters, but must also result from an approach of total optimisation and consistency with the functional issues of the rest of the network.With more than 430 km of new line planned, coordinating this design work in a relatively short timeframe will be a significant challenge.In addition, the design studies for the Ain Sebaa-Nouaceur section circumnavigating the Casablanca hub also notably include the design studies for nearly 60 km of four-track widening works, with very busy railway traffic in a restrictive urban setting. This challenge will call for high mobilisation from ONCF’s stakeholders (engineering, operation, maintenance, commercial, tests, etc) and design offices.Finally, the project owner will be required to decide upon the best sequencing policy for this project block, taking into account the need to eliminate network bottlenecks, maximise capacity and optimise investment.