a referendum. Today, the ASEAG (Aachener Straßenbahn und Energieversorgungs-AG, literally "Aachen tram and power supply company") operates a bus network with 68 bus routes. Because of the location at the border, many bus routes extend to Belgium and the Netherlands. Lines 14 to Eupen, Belgium and 44 to Heerlen, Netherlands are jointly operated with Transport en Commun and Veolia Transport Nederland, respectively. ASEAG is one of the main participants in the Aachener Verkehrsverbund (AVV), a tariff association in the region. Along with ASEAG, city bus routes of Aachen are served by private contractors such as Sadar, Taeter, Schlömer, or DB Regio Bus. Line 350, which runs from Maastricht, also enters Aachen. Roads Aachen is connected to the Autobahn A4 (west-east), A44 (north-south) and A544 (a smaller motorway from the A4 to the Europaplatz near the city centre). There are plans to eliminate traffic jams at the Aachen road interchange. Airport Maastricht Aachen Airport is the main airport of Aachen and Maastricht. It is located around northwest of Aachen. There is a shuttle-service between Aachen and the airport. Recreational aviation is served by the (formerly military) Aachen Merzbrück Airfield. Charlemagne Prize Since 1950, a committee of Aachen citizens annually awards the Charlemagne Prize () to personalities of outstanding service to the unification of Europe. It is traditionally awarded on Ascension Day at the City Hall. In 2016, the Charlemagne Award was awarded to Pope Francis. The International Charlemagne Prize of Aachen was awarded in the year 2000 to US president Bill Clinton, for his special personal contribution to co-operation with the states of Europe, for the preservation of peace, freedom, democracy and human rights in Europe, and for his support of the enlargement of the European Union. In 2004, Pope John Paul II's efforts to unite Europe were honoured with an "Extraordinary Charlemagne Medal", which was awarded for the only time ever. Literature Aix is the destination in Robert Browning's poem "How They Brought the Good News from Ghent to Aix", which was published in Dramatic Romances and Lyrics, 1845. The poem is a first-person narrative told, in breathless galloping meter, by one of three riders; an urgent midnight errand to deliver "the news which alone could save Aix from her fate". Notable people Twin towns – sister cities Aachen is twinned with: Montebourg, France (1960) Reims, France (1967) Halifax, England (1979) Toledo, Spain (1985) Ningbo, China (1986) Naumburg, Germany (1988)