An aerial photo taken on September 5, 2021 of the Nanquan section of the just-opened Taihu tunnel in east China's Jiangsu Province. Credit: Li Bo/Xinhua via Getty Images BY Yong Xiong and Karla Cripps, After nearly four years of construction, China's longest underwater highway tunnel is now open to vehicle traffic. At a length of 10.79 kilometers (6.65 miles), the Taihu tunnel stretches under Lake Taihu in eastern China's Jiangsu Province, about 50 kilometers east of Shanghai. According to government officials in Jiangsu, the tunnel was built at a cost 9.9 billion yuan (about $1.56 billion). Construction began on January 9, 2018. Over 2 million cubic meters of concrete were used to build the two-way tunnel, which has six lanes and is 17.45 meters wide, reports China's official news agency, Xinhua. The ceiling of the tunnel has been outfitted with colorful LED lights, designed to prevent driver fatigue. A view of the LED ceiling installed in the 10.79-kilometer tunnel u...