The Airport Expressway (), officially the S12, is a controlled-access highway in Beijing, China, which links central Beijing to the Beijing Capital International Airport. It is just under 20 km in length. Opened in 1993, the expressway links Sanyuanqiao on the northeastern 3rd Ring Road to Beijing Airport. Another expressway, the 2nd Airport Expressway, was built in 2008 prior to the Beijing Olympics to serve traffic from the city to the airport. Route The Airport Expressway runs entirely within the confines of the municipality of Beijing. Basic Route: Beijing (Sanyuanqiao - Siyuan - Beigao - Xiaotianzu - Beijing Capital International Airport) History The expressway opened on September 14, 1993, following a year-long construction effort which began on July 2, 1992. Previously, all traffic used the old Airport Road (G101), which was tested to the limit in the early 1990s. This expressway has slashed driving time to the airport from the previous hour (using the old airport road) to just around 15 minutes. It is convenient and traffic is usually smooth. Extension into the 2nd Ring Road A 2.5 km stretch of expressway links Sanyuanqiao on the 3rd Ring Road to the area between Dongzhimen and Xiaojieqiao on the 2nd Ring Road. Construction started in 2004; it was finished in 2006. Alternate routes Further approach routes to the airport were built in the first decade of the 21st century. The Northern Airport Line (机场北线), completed between 2005 and 2006, connected the Jingcheng Expressway with the northern part of the airport, to form a northern approach route. The route commences at Lutong, just over halfway between the 5th Ring Road and the 6th Ring Road, on the Jingcheng Expressway. In 2008, another route, the 2nd Airport Expressway, was built between the eastern 5th Ring Road and the airport in time for the Beijing Olympics. Both routes have significantly alleviated traffic to the airport from the city proper. Road conditions Speed limit Leftmost lane: minimum 100 km/h, maximum 120 km/h. Other lanes: minimum 60 – 80 km/h, maximum 100 km/h. Tolls The toll collection on the Airport Expressway has a contentious history. Construction was funded by the government using a bank loan in 1993, and residents began to dispute the rationale for the toll collection several years after the road was completed, doubting that the loan was paid off and that most of the revenue was actually used to pay back the loan.