These trunk roads make use of several road tunnels leading to the district. Of these, the Lion Rock Tunnel used by Route 1, is the oldest, having opened in 1967 to replace the overcrowded Tai Po Road to Sham Shui Po. Despite the opening of further tunnels over the years, it remains the most direct route to central Kowloon, and thus the most heavily travelled. The Lion Rock Tunnel was followed by the Shing Mun Tunnels on Route 9 in 1990, the Tate's Cairn Tunnel on Route 2 in 1991, and most recently the Tsing Sha Highway on Route 8 (consisting of the Eagle's Nest Tunnel and Sha Tin Heights Tunnel) in 2008.