Currently the longest immersed tube tunnel is the tunnel portion of the Hong Kong–Zhuhai–Macau Bridge, completed in 2018. The HZMB tunnel is set at a depth of below sea level. Its length will be surpassed by with the completion of the Shenzhen–Zhongshan Bridge in 2024. The SZB project includes a immersed tube which also will be the world's widest immersed tube, carrying eight traffic lanes. Prior to the completion of the Marmaray and HZMB tunnels, the Transbay Tube, completed in 1969, was the world's deepest and longest immersed tube, at below water level and long.