| Start: | Baoshan District |
| End: | Sancha Port |
| Length: | 2880 km |
| Speed: | 80 km/h |
The Outer Ring tunnel, also known as the Taihe Road Tunnel, is a highway tunnel under the Huangpu River in Shanghai. The tunnel serves as part of the S20 Expressway and was completed on June 21, 2023. The tunnel runs east to west from Baoshan District to Sancha Port after crossing the Huangpu. The tunnel is long and features 8 lanes with a speed limit of 80 km/h, which made it the longest underwater tunnel in Asia and third worldwide by length.[1]
The tunnel has been closed for 12 months due to construction since March 22, 2024.[2]