The 4th Ring Road () is a controlled-access expressway ring road in Beijing, China which runs around the city, with a radius of approximately from city centre. The total length of the road is . There are 147 bridges and viaducts that run the length of the Ring Road. The first section, the northern corridor, was completed in preparation for the 1990 Asian Games. The Ring Road was 'enclosed' in a full circle in June 2001, with standard controlled-access expressway throughout. Route The 4th Ring Road runs within the confines of the city of Beijing, more like a rectangle than a circle. The route travels past: Siyuan Bridge - Chaoyang Park Area - Sihui - Sifang Bridge - Shibalidian - Dahongmen - Majialou - Yuegezhuang Bridge - Fengtai Area - Sijiqing Area - Zhongguancun Area - Jianxiang - Asian Games Village Area - Wanghe Bridge - Siyuan Bridge The entire express road is complete and open to traffic. History Already in the early 1990s, the northern stretch of the 4th Ring Road from Zhongguancun to Siyuan Bridge existed as a ring road, albeit with far narrower road conditions and with traffic lights. Only three flyover viaducts—those at Jianxiang Bridge, Anhui Bridge and Siyuan Bridge—existed. To commemorate the 50th anniversary of the People's Republic of China, the eastern stretch of the 4th Ring Road was opened from Siyuan Bridge to Shibalidian around October 1, 1999. This was the first part of the ring road to be opened as an 8-lane expressway (4 lanes per direction, not including an emergency belt). The northern part of the 4th Ring Road from Jianxiang Bridge to Siyuan Bridge was converted to an 8-lane expressway in late September 2000. Later that year, the southern part from Shibalidian through to Fengtai opened to traffic, as was the case with the northwestern part. By June 2001, the entire 4th Ring Road had been converted into an expressway-standard thoroughfare. In early 2004, the speed limit was reduced to a unified 80 km/h (minimum speed limit: 50 km/h). In September 2004, the 4th Ring Road underwent a massive sign change. Exit numberings were unified at last—bidirectionally (this was previously not the case). A new overpass in the northern stretch was put into operation in October 2004, near the Beichen area. Road conditions Speed limit Previously: first lane, min. 80 km/h, max. 100 km/h; second lane, min. 70 km/h, max. 90