will be finished by the end of 2014 in harmonization with the e-ticket system. Tram lines no. 4 and 6 are the busiest city tram lines in the world, with one of the world's longest trams (54-metre long Siemens Combino) running at 2–3-minute intervals at peak time and 4–5 minutes off-peak. Day services are usually from 4am until between 11pm and 0:30am. Hungarian State Railways operates an extensive network of commuter rail services, their importance in the suburban commuter passenger traffic is significant, but in travel within the city is limited. The organiser of public transport in Budapest is the municipal corporation Centre for Budapest Transport (Budapesti Közlekedési Központ – BKK), that is responsible for planning and organising network and services, planning and developing tariff concepts, attending to public service procurer duties, managing public service contracts, operating controlling and monitoring systems, setting and monitoring service level agreements related to public transport, attending to customer service duties, selling and monitoring tickets and passes, attending to integrated passenger information duties, unified Budapest-centric traffic control within public transport, attending to duties related to river navigation, plus the management of Budapest roads, operating taxi stations, unified control of bicycle traffic development in the capital, preparing parking strategy and developing an operational concept, preparation of road traffic management, developing an optimal traffic management system, organising and co-ordinating road reconstruction and more, in short, everything which is related to transport in the city. Roads and railways Budapest is the most important Hungarian road terminus, all of the major highways and railways end within the city limits. The road system in the city is designed in a similar manner to that of Paris, with several ring roads, and avenues radiating out from the center. Ring road M0 around Budapest is nearly completed, with only one section missing on the west side due to local disputes. The ring road is in length, and once finished it will be of highway in length. The city is a vital traffic hub because all major European roads and European railway lines lead to Budapest. The Danube was and is still today an important water-way and this region in the centre of the Carpathian Basin lies at the cross-roads of trade routes. Hungarian main line railways are operated by Hungarian State Railways. There are three main railway station in Budapest, Keleti (Eastern), Nyugati (Western) and Déli (Southern), operating both domestic and international