A part of the Yau Ma Tei-bound lanes of the Central Kowloon Bypass were closed as of 2.40pm on Friday following a traffic accident.
The Transport Department said only one lane remains available to motorists.
An articulated vehicle crashed into a concrete barrier inside the tunnel at around 9am, shedding its load onto the road.
Online footage purportedly showed the crash had caused damage to the tunnel's wall next to the slow lane.
No injuries were reported.
Edited by Aaron Tam
