KUALA KUBU BARU: A collision involving two trailer trucks caused an eight-kilometre traffic jam along the southbound stretch of the North-South Expressway near Hulu Selangor.

The crash occurred at 1.30pm today when a container truck rammed into the rear left side of a low-loader trailer that had stopped abruptly following a brake system malfunction.

Hulu Selangor police chief Superintendent M. Manimaran said preliminary investigations found that the trailer, driven by a man in his 40s, was travelling from Tanjung Malim towards Sungai Buaya.

"The trailer, which was not carrying any cargo, was travelling in the middle lane when it suddenly stopped after experiencing a malfunction in its air brake system, which affected the rear wheels.