South Korea fell silent Thursday, with heavy trucks banned and businesses opening late, as more than 600,000 students took the high-stakes annual college entrance exam that could define their future in the ultracompetitive country.

Success in the exam - which teenage South Koreans spend years preparing for - means a place in one of the elite colleges seen as key to a future career and even marriage prospects.

To clear the roads for the 606,000 students to ensure they arrived on time, government offices, major businesses and even Seoul's stock market opened an hour later than usual at 10 am.