The 7.8-kilometer-long trunk highway tunnel designed to cross Taihu Lake has cast its first roof concrete. The tunnel links the towns of Mashan and Zhoutie in Jiangsu Province's Wuxi City by creating a shortcut under one of China's largest lakes. The roof concrete is 1.4 meters thick and 20 meters wide, covering nearly 1,200 square meters, or about three standard basketball courts. After completion, the fast track will greatly improve transportation between county-level and urban Wuxi, boosting the domestic economy along the route.