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A Thai resident crosses a flooded street in Bangkok, Thailand, Saturday, Nov. 5, 2011. Floodwaters lapped Bangkok's largest outdoor market Saturday as officials warned that no major barriers now stood in the way to prevent the water from reaching the heart of the Thai capital. (AP Photo/Aaron Favila)

Floods threaten Bangkok trains

Advancing pools of filthy water threatened the Thai capital's subway system Monday and surrounded the emergency headquarters set up to deal with flooding that has claimed more than 500 lives nationwide.