The tourist train "Le Petit Train des Alpilles" operated by RDT13 runs on Wednesdays, Thursdays, Fridays and Saturdays from 1 June to 8 September 2012. The train pulled by a diesel engine runs on the 7 km line between Arles and Fontvielle, through fields of rice, wheat, rapeseed and sunflower.
Details at their website.
NOTE - Train des Alpilles has ceased to operate.