Last month more than 30 provincial taxi drivers drank poison and collapsed together on the busiest shopping street in Beijing in a dramatic protest against economic and working conditions in their home town.The drivers, who the police say all survived, were from Suifenhe, a city on the Russian border in the northeastern province of Heilongjiang. Such lurid acts of protest are an ancient tradition in China but the extremity of their action highlights one of the biggest problems facing Beijing as it tries to manage the worst economic slowdown in nearly three decades: a deepening provincial economic divide.