Most trunk roads including expressways in Hong Kong have route numbers, which enable motorists to quickly find the most convenient and direct route when driving from one district to another. Route Number Shields are included on direction traffic signs to guide motorists.

Nine routes have been designated under the Route Numbering System. Details of these nine routes are listed on the right:

Route route 1Aberdeen -- Lok Ma Chau

Aberdeen -- Wong Chuk Hang -- Causeway Bay -- Hung Hom -- Kowloon Tong -- Sha Tin -- Tai Po -- Fanling -- Sheung Shui -- Lok Ma Chau

The route passes through the Aberdeen Tunnel, Cross Harbour Tunnel and Lion Rock Tunnel.

Route route 2

Ngau Tau Kok -- Lok Ma Chau

Ngau Tau Kok -- Hung Hom -- Yau Ma Tei -- Lai Chi Kok -- Kwai Chung -- Tsuen Wan -- Tuen Mun -- Yuen Long -- Lok Ma Chau ( to join Route 1 )

The route passes through the Airport Tunnel.

Route route 3Sai Ying Pun -- Yuen Long

Sai Ying Pun -- Yau Ma Tei -- Lai Chi Kok -- Kwai Chung -- Tsing Yi -- Yuen Long

The route passes through the Western Harbour Crossing, Rambler Channel Bridge, Cheung Ching Tunnel, Ting Kau Bridge and Tai Lam Tunnel.

Route route 4

Lai Chi Kok -- Kwun Tong -- Tseung Kwan O

The route passes through the Tseung Kwan O Tunnel.

Route route 5

Sha Tin -- Tsuen Wan

The route passes through the Shing Mun Tunnel.

Route route 6

Quarry Bay -- Kwun Tong -- Ma Liu Shui

The route passes through the Eastern Harbour Crossing and the Tate's Cairn Tunnel ( to join Route 1 )

 Route route 7

Causeway Bay -- Central -- Sai Ying Pun

A future waterfront road is to extend this route to Aberdeen.

 Route route 8

Island Eastern Corridor from Chai Wan to Causeway Bay

Route route 9

Chek Lap Kok -- Tsing Yi

Chek Lap Kok -- Tung Chung -- Ma Wan -- Tsing Yi

The route passes through the Kap Shui Mun Bridge, Tsing Ma Bridge and join the Route 3 in Tsing Yi.

A future extension to Tai Wai is under planning.