Tuen Mun Road is a major expressway in Hong Kong which connects Tuen Mun with Tsuen Wan, within the New Territories. It is part of Hong Kong's Route 9, which circumnavigates the New Territories. Opened in 1978, it was once the major trunk route linking the northwest New Territories to urban Kowloon and is known for its frequent traffic jams and road accidents owing to its early design and heavy usage. As a result, speed limits have been enforced to due to geometric constraints. Alignment The highway leads off Yuen Long Highway at Lam Tei Interchange, where it also interchanges with Castle Peak Road and Tsing Lun Road. The next section (considered from west to east) is a dual 3 lane road through the town centre of Tuen Mun, but this section is not a statutorily designated (limited-access) expressway. Expressway regulations apply from the junction with Wong Chu Road, where it widens to 3 lanes and climbs the hillside beside Sam Shing Hui. It then descends into So Kwun Wat, crossing the rural area on an embankment. The road then rises again before descending into Siu Lam Interchange, where it interchanges with Castle Peak Road. From here, the highway crosses the mouth of Tai Lam Chung, and starts climbing the hillsides of Tai Lam through split level terraces (the lower one being the Tuen Mun bound carriageway). The two carriageways join before bypassing the village of Tsing Lung Tau to the north. This section of road is constructed upon various deep cuttings and high embankments. Afterwards, the road crosses over the village of Sham Tseng (situated in a valley) to Sham Tseng Interchange, where it interchanges once again with Castle Peak Road. The road then climbs towards Ting Kau Interchange with its widest section (5+3 lanes). After this junction with Tsing Long Highway, the Highway crosses the valley of Ting Kau with various viaducts, with the Tsuen Wan bound carriageway climbing to meet the split level section into Tsuen Wan. This section is characterised by its tight bends and steep descent eastbound. The two carriageways join as the highway terminates and leads into Cheung Pei Shan Road, with slip roads connecting with Tsuen Wan Road and Castle Peak Road (Tsuen Wan Section). Interchanges History and development Tuen Mun Road was one of Hong Kong's first high speed roads, and the first expressway. Its construction proved to be a great challenge