Complex sentence: The motorway has not undergone any significant changes since that time, only covering of a section at the School of Saint Cyr and the widening of the roadway to 4 lanes in one direction and 3 in the other.
Split into simpler sentences: The motorway has not undergone any significant changes since that time. The changes that have occured include the covering of a section at the School of Saint Cyr and the widening of the roadway to 4 lanes in one direction and 3 in the other.