Article: A national railway system that extends throughout the country and into Spain, is supported and administered by Comboios de Portugal. Rail transport of passengers and goods is derived using the 2,791 km (1,734 mi) of railway lines currently in service, of which 1,430 km (889 mi) are electrified and about 900 km (559 mi) allow train speeds greater than 120 km/h (75 mph). The railway network is managed by the REFER while the transport of passengers and goods are the responsibility of Comboios de Portugal (CP), both public companies. In 2006 the CP carried 133 million passengers and 9,750,000 t (9,600,000 long tons; 10,700,000 short tons) of goods.

Now answer this question: How long is the amount of railway lines that permit speeds greater than 120 km/h?
900 km (559 mi)