AlHijjah 10, 1432, Nov 6, 2011, SPA -- The nationwide death toll from Thailand's worst floods in half a century climbed past 500 Sunday, as the polluted black water continued its march into Bangkok and authorities ordered a spate of new evacuations in the sprawling capital, according to AP. Floodwaters also poured over a road running underneath the city's Mo Chit Skytrain station, the northernmost stop on Bangkok's elevated subway system. The road was still passable, and train service has not yet been affected, but the inundation illustrates how far flooding has progressed into the city. Mo Chit is located just a few miles (kilometers) north of the city's central business district, which has remained dry so far. Flooding has also reached roads at three subway stops in northern Bangkok, but all remained open Sunday. Relentless rainfall has pummeled vast swaths of Thailand since late July, swamping the country and killing 506 people, according to the latest government statistics. Most of those killed have drowned, while a handful of people have died from flood-related electrocutions. No deaths have been reported in Bangkok. The nearby province of Ayutthaya, which has been submerged for more than one month, has the highest toll with 90 reported dead. Floodwaters have begun receding in some provinces north of the capital, and a major cleanup is planned in Ayutthaya this week. But the runoff has massed around Bangkok and completely submerged some of the city's outer neighborhoods. On Sunday, Bangkok Gov. Sukhumbhand Paribatra ordered another wave of evacuations in several neighborhoods in the west and east. In all, evacuations have been ordered in nine of the capital's 50 districts - up from eight a day earlier. Seven other districts are partially inundated and residents in parts of those have also been told to leave. Also Sunday, floodwaters began approaching a main road near the city's Mo Chit bus terminal, a major gateway to northern Thailand. The bus station remained open, though, traffic police chief Uthaiwan Kaewsa-ard said. Mo Chit is close to the famed Chatuchak Weekend Market, Bangkok's largest outdoor shopping zone. The market, a major tourist attraction, was officially open Sunday. But with water pouring past its eastern edge for the second day, most vendors and customers stayed away.