In the north of France, the high-speed lines are also used to run regional trains over longer distances. There are currently train from Lille to Dunkerque. This takes half an hour. Other lines run to Calais, in forty minutes, or to Boulogne-sur-Mer in 55. In 2007, a line to Arras was opened, which is also very successful. Unfortunately, there are some problems with this approach. First, only high-speed lines can be used that are not saturated, because these trains run slower than regular TGVs. Secondly, using a TGV line costs more to the client, they have to pay extra. This makes these services more expensive.