BEIJING, Sept. 30 (Xinhua) -- The Beijing government has finally decided to cut subway fares by about 30 percent amid efforts to boost public transport, ease road congestion and improve air quality ahead of the Olympics.     A single pricing system which means a one-way ticket costs just two yuan (27 U.S. cents), down from three yuan, will be introduced on Oct. 7, the same day as the opening of a new subway line which will run through the heart of the city from north to south.     Construction on the 27.6-km new line, Beijing's No. 5 Subway Line, began in December 2002, costing 12 billion yuan (about 1.6 billion U.S. dollars).     Beijing now has four subway lines with a total mileage of 114 km and they transport about 1.15 million passengers daily, 15 percent of the total commuters.     According to the municipal government, Beijing will add three subway lines next year and the total mileage will reach 200 km.     Before the final decision of lowering fares was made, a public hearing was held on Wednesday by the Beijing Municipal Development and Reform Commission, in which two subway pricing systems were proposed: lowering the price of a one-way ticket to two yuan; adopting a flexible pricing system ranging from two yuan to four yuan according to the distance one travels.     Most of the 25 people attending the meeting, including transport experts, passengers, representatives of the metro operator and government officials, favored the single pricing system, under which 80 percent of commuters will save 1.3 yuan (17 cents) every trip.     "The single pricing system is easier to adopt and cheaper for passengers. As more subway lines are completed, more people will choose to take the subway, the above-ground traffic jams will be eased and air quality will be better," said Liu Tongliang, head ofthe Beijing Municipal Transportation Administration Bureau.     Taking into account the inevitable rise of the number of subway passengers, local traffic authorities have promised to increase subway trains and shorten intervals between trains to boost the transport capacity.     Meanwhile, Liu said the government would increase expenditure on public transport by 1 billion yuan (133 million U.S. dollars) annually after the single price scheme is adopted.     Road congestion has been a major problem yet to be solved for the Chinese capital, which now registers more than 3 million vehicles, and citizens have been urged to take public transport to ease traffic pressure.     The municipal government has been giving discounts of up to 60 percent for residents -- and even 80 percent for students --- for bus tickets since the beginning of this year to encourage people to choose public transport.     The city aims to raise the proportion of citizens choosing public transport from about 30 percent to more than 40 percent by 2010, according to Liu Xiaoming, deputy director of the Beijing Municipal Commission of Communications.     To achieve this goal, Beijing will raise the number of buses from 18,000 to 21,000 by 2010, and extend the metro line from present 114 km to at least 270 km, Liu said.