several low-cost air companies operate on the island. Air Italy (formerly known as Meridiana) was an airline headquartered in the airport of Olbia; it was founded as Alisarda in 1963 by the Aga Khan IV. The development of Alisarda followed the development of Costa Smeralda in the northeast part of the island, a well known vacation spot among billionaires and film actors worldwide. Seaports The ferry companies operating on the island are Tirrenia di Navigazione, Moby Lines, Corsica Ferries - Sardinia Ferries,Grandi Navi Veloci, Grimaldi Lines, Corsica Linea; they link the Sardinian seaports of Porto Torres, Olbia, Golfo Aranci, Arbatax, Santa Teresa Gallura and Cagliari with Civitavecchia, Genoa, Livorno, Naples, Palermo, Trapani, Piombino in Italy, Marseille, Toulon, Bonifacio, Propriano and Ajaccio in France and Barcelona in Spain. Caronte & Tourist and Delcomar links the main island to the islands of La Maddalena and San Pietro. About 40 tourist harbours are located along the Sardinian coasts. Roads Sardinia is the only Italian region without Autostrade (en:motorways), but the road network is well developed with a system of no-toll roads with dual carriageway, called superstrade ('super roads') that connect the principal towns and the main airports and seaports; the speed limit is /. The principal road is the SS131 "Carlo Felice", linking the south with the north of the island, crossing the most historic regions of Porto Torres and Cagliari; it is part of European route E25. The SS 131 d.c.n links Oristano with Olbia, crossing the hinterland Nuoro region. Other roads designed for high-capacity traffic link Sassari with Alghero, Sassari with Tempio Pausania, Sassari – Olbia, Cagliari – Tortolì, Cagliari – Iglesias, Nuoro – Lanusei. A work in progress is converting the main routes to highway standards, with the elimination of all intersections. The secondary inland and mountain roads are generally narrow with many hairpin turns, so the speed limits are very low. Public transport buses reach every town and village at least once a day; however, due to the low density of population, the smallest territories are reachable only by car. The Azienda Regionale Sarda Trasporti (ARST) is the public regional bus transport agency. Networks of city buses serve the main towns (Cagliari, Iglesias, Oristano, Alghero, Sassari, Nuoro, Carbonia and Olbia). In Sardinia 1,295,462 vehicles circulate, equal to 613 per 1,000 inhabitants. Railways The Sardinian railway system was developed starting from the 19th century by the Welsh engineer Benjamin Piercy.