BEIJING, July 21 (Xinhua) -- Chinese authorities are bracing for the longest total solar eclipse of the century with emergency measures for possible inconveniences triggered by the phenomenon.

Graphics shows the solar eclipse lasting for over six minutes on July 22, according to the Chinese Academy of Sciences Purple Mountain Observatory. (Xinhua/Meng Lijing) Photo Gallery>>>

    In response to the call of the State Council, the cabinet, to prepare for any inconveniences to people caused by the total solar eclipse, tourism department has advised tourists to avoid stampedes during observation.

    The total solar eclipse is to occur on Wednesday morning. About 300 million people along the Yangtze River will have the chance to view the event. People in regions beyond the river valley, including Beijing, can observe a partial eclipse.

    The eclipse, which lasts as long as six minutes and 43 seconds, will not be surpassed in duration until June 13, 2132.

    As the daytime darkness for a few minutes may cause inconvenience for traffic and work in the open air, governments in many cities have ordered local traffic departments to turn on roadlights and send additional police force to prevent traffic jams in the rush hour on Wednesday morning.

Graphics shows five highlights of the total solar eclipse recommended by the astronomers on July 21, 2009.(Xinhua/Zheng Yue) Photo Gallery>>>

    All the police in Shanghai will be on duty to deal with heavy traffic, said the municipal public security bureau.

    More patrol police will be deployed on Shanghai's major streets to avoid traffic congestion and the public are urged to prevent stampede in huge gatherings.

    Cities in the river valley, including Shanghai and Hangzhou, will turn on all road lights Wednesday morning to ensure smooth traffic in darkness.

    Some scientists predicted that the temperature in regions covered in the total solar eclipse route may drop by five to 15 degrees Celsius on Wednesday, when the Sun is blocked out.

Graphics shows the path of total solar eclipse lasting for over six minutes on July 22 in China, according to the Chinese Academy of Sciences Purple Mountain Observatory. (Xinhua/Meng Lijing) Photo Gallery>>>

    Experts warned that the total eclipse might disturb radio transmission, GPS satellite signal and telecommunications.

    According to the National Meteorological Center, thundershowers or thick clouds may overcast many cities in the Yangtze River Valley, including Shanghai, Chongqing and Wuhan as well as the eight sites with the best views recommended by the National Astronomical Observatories.

Special report: July 22: Longest total solar eclipse in 500 years