156 Which of the following is NOT the purpose of traffic control for closing down roads and bridges? (A) Roads and bridges are prone to accidents, and motorists who go through these sections are putting themselves in danger； therefore, roads or bridges closed in advance to prevent motorists entering dangerous areas may lead to death or loss of property； (B) Roads under construction or which have already been damaged should be closed down to speed up repairs and ensure driver safety； (C) Closing down roads and bridges causes inconvenience for drivers and interrupts their trips.