Transport in Luxembourg is ensured principally by road, rail and air. There are also services along the River Moselle which forms the border with Germany. The road network has been significantly modernised in recent years with motorways to adjacent countries. The advent of the high-speed TGV link to Paris has led to renovation of the city’s railway station while a new passenger terminal at Luxembourg Airport has recently been opened. Trams in the capital were introduced in December 2017 and there are plans for light-rail lines in adjacent areas. The speed limit is normally 130 km/h, 110 km/h in rainy weather. With 56.8 km of motorway per 1,000 km2, Luxembourg probably now has the highest density of motorways in Europe. Comprehensive bus services linking the towns and villages of the Grand Duchy of Luxembourg are contracted out to private operators by the RGTR (Régime général des transportations routiers) under the Ministry of Transport. Luxembourg City is served by 163 of its own AVL (Autobus de la Ville de Luxembourg) buses transportation in some 28 million passengers per year (2007). Also, the letters on the license plate can give ownership away to those that know how that system works. There are 25 regular bus routes plus special bus services through the night