In 1978, RATP possessed a large number of outdated Sprague-Thomson trains, many of which were rapidly approaching 60 and 70 years old. With the MF 77 trains in place along Lines 8, 9 and 13, most of the Sprague were replaced. However, there were still some trains in service along Line 9, which were approaching 80 years old. Those trains were finally retired in 1983, reducing the average age of rolling stock to 14 years. Anticipating further aging in its rolling stock, RATP changed its policy regarding replacement of rolling stock to avoid a massive, simultaneous replacement of all rolling stock.