SNCF's BB 25500 class are part of a series of electric locomotives built by Alsthom. They are the dual system version of the BB 17000 (AC) and BB 8500 (DC) locomotives (17000+8500=25500). They are fitted with monomotor bogies with two different gear ratios. This allows them to have either increased tractive effort for freight, or a higher top speed. This makes them suitable for both freight and passenger trains.[3]
They were built in three distinct batches leading to detail differences. They remain in use as mixed traffic locomotives, mostly with TER and Transilien.