Both road surfaces acceptable and durable

PUBLISHED : Wednesday, 20 August, 1997, 12:00am
UPDATED : Wednesday, 20 August, 1997, 12:00am

I refer to the letter from Dr Tseng Hing-chuen headlined, 'Unhappy with asphalt surface' (South China Morning Post, July 21), and would like to provide the following information in reply: The road slab inside the Lion Rock Tunnel is basically reinforced concrete slab. The tunnel has two tunnel tubes. In the 1980s, the concrete road slab of one of the tubes was overlaid with a layer of bituminous (or asphalt, the term used in Dr Tseng's letter) surfacing to protect the aged concrete road surface. No overlay has been done for the road surface in the other tube.

In comparing the road surface between the Lion Rock Tunnel and Tate's Cairn Tunnel, the road slab in Lion Rock Tunnel (the first tube opened in 1967, the second in 1978) has been subjected to a lot more traffic loading than the road slab in the Tate's Cairn Tunnel which was opened only six years ago.

According to our record, the bituminous road surface of the Lion Rock Tunnel was last resurfaced in 1993/94. In the subsequent four years, only minor repairs were carried out. It is not true, as Dr Tseng's claims, that the road slab in the Lion Rock Tunnel has been resurfaced every year.

Both concrete slab and bituminous slab are acceptable and durable road construction and are adopted worldwide. Each type has its pros and cons and there is no evidence to show that one is absolutely better than the other. For instance bituminous road slab provides a road surface with a better riding quality. Nevertheless, whichever type of pavement is used, whether concrete or bituminous, we endeavour to arrange urgent repair works for any potholes or road defects in order to maintain a safe road surface for road users. Our target is to repair potholes within 48 hours after receipt of a complaint.

For potholes identified on expressways or trunk roads like the Lion Rock Tunnel, we adopted an even higher standard such that immediate repairs are arranged. When traffic is heavy, temporary patching works are carried out in the first instance, and full repair works follow as soon as the necessary traffic arrangements are made.

LUCY HO SAU-PING Senior Engineer/Highways Complaints Highways Department