A number of major road projects continue in Hong Kong despite the recent emphasis on rail and metro systems. Adrian Greeman looks at an upgrade for the Castle Peak road.
Hong Kong's steep, rocky hillsides make for a spectacular landscape and a dramatic coastline. And they also mean spectacular engineering works at times.
Few could be more visually dramatic than the Castle Peak road upgrade. The conventional highway, with a single carriageway in each direction, clings to the base of sometimes precipitous slopes bounding the southern coast of the mainland New Territories. Most of its 7km stretch is now being widened and over 1M. m 3of rock is being cut from the steep slopes.
Castle Peak's winding route carries traffic from Tsuen Wan just outside Kowloon and the better known parts of Hong Kong, to the town of Tuen Mun and then northward into the fields and farm areas. It passes the shipping channels opposite Tsing Yi island and the much larger mass of Lantau, where the international airport now sits.
The road dates from earlier times as a British colony, when the New Territories were a rural area supplying food and water to the city. But the building of a major dual three lane highway on high hillside viaducts along the coast to Tuen Mun township in the 1980s reduced the importance of the Castle Peak road. It has since carried only local traffic and overspill at peak times.
But Hong Kong never stands still. Increasingly the New Territories has become an area for new town development, first on the east side in the 1980s as housing demand grew, and now in recent years on the west side.
Tuen Mun has also grown with the development of the airport, and now this whole area is opening up due in particular to the dramatic economic boom across the border in Shenzhen and beyond (NCEI May).
A western road link across the border is scheduled which will bring more cars and trucks to the expanding container terminals.
Even along the Castle Peak road there have been a substantial number of higher end residential and tourist developments.
Demand now jams the Tuen Mun highway quite frequently.
'A single accident can cause major hold-ups, ' explains Tsui Wai, chief engineer in the Highways Department's major works project management office, and responsible for Castle Peak.
Relief will come with the new Route 10 (see box) but the southern section will not complete until 2008 and so the coastal road is being upgraded. A joint venture of Mouchel and Halcrow worked on the design, mainly following the alignment of the existing road.
'The problem is to carry out a major earthworks programme to widen the road on steep hillsides which can have inclines up to 50 degrees, ' says Tsui Wai. Proximity of the Tuen Mun highway above means in places work comes to within 5m of the viaduct pile foundations.
Three contracts have been let since August last year for roughly equal sections of the work. China State Construction Engineering Corporation began work first on a US$108M contract for the central 2.5km section, overlooking Hong Kong's three great bridges; the Tsing Ma crossing and the Ting Kau connection. In November Japan's Maeda was awarded a US$98M contract and the third was let in April to China State Construction Engineering Hong Kong for US$123M.
On the first, central, contract the greatest concern as work has got under way has been ensuring slope stability as the typical decomposed granite and volcanic tuff is stripped away.
'There are a large number of loose boulders, ' says Paul Appleton, senior resident engineer on the project. These have had to be removed individually, sometimes after stabilising them with drilled through anchors.
The danger of landslips and rockfalls is considerable in Hong Kong because of the sudden massive downpours that can sweep in with the summer typhoons. Rainfall of 850mm in a day is not unknown.
Slope safety measures, with rock fencing and soil nailing, meant initial progress was slow but it has now picked up and four large rock slope excavations are under way. Some 30,000m 3ofmaterial a month is being removed from these four locations; four further slopes to come will bring the total of rock to be excavated to 250,000m 3.Fortunately the West Rail project just a few kilometres away needs fill for embankments and the contractor is transporting large amount to its major seabed reclamation for the DisneyWorld project on Lantau island.
Five other areas still require soil nailing. And in three sites work on large diameter bored piles for three retaining walls has begun. There are also foundations for a section of viaduct.
'Rigs are installing one 2.5m diameter pile every 10 days, ' says Appleton. These are short for Hong Kong, being a mere 20m deep, though with socketing into rock of between 7m and 10m.
'There is also a full noise enclosure to build and a small section of sea reclamation, ' he says. Three of 15 wall panels for a new seawall have been cast so far, following fill placement to a level of 4m above sea level using barge mounted excavators.
Major work is still to come for this project which is due to complete in just over two years time.
But good weather this year has meant progress is looking good, says Appleton.
Despite the Hong Kong government's current emphasis on rail transport, several major road projects are in planning or early construction. Not least of these is Route Nine which has just been given funding approval for a 6km section linking Kowloon to the 1970s new town of ShaTin. To pass through the high hills that characterise Hong Kong, a pair of twin three lane tunnels are required, the twin bore Eagles Nest being the longer at 2.1km. A second twin tunnel just north will be 1km long.
Construction begins next year.
A viaduct section will run on into the busy main container port area in northern Kowloon, where a second section of the highway will run, again on viaduct, through the terminals and then up across the 900m wide Rambler Channel entrance on the dramatic Stonecutters cable stay bridge, whose 1,000m span will make it briefly a record holder, when completed. Viaduct work was let in April, a US$197M contract going to China Harbour Engineering Company (Group).
The route will cut through Tsing Yi island in another twin bore dual three lane tunnel, the 1.2km long Nam Wan tunnel, connecting into the network of links between Hong Kong, Lantau island and the western New Territories. Currently three major bridges cross the water at this point, to be joined eventually by the 1,418m span Tsing Lung suspension bridge from Lantau to the north. Design work on this exrtraordinary low profile bridge with a super-slim deck is under way and construction is due to begin in 2003 for completion five years later.
Tsing Lung is part of Route 10 which by 2008 will complement the Tuen Men highway and eventually link to a northern section, though construction of this has been deferred until possibly 2011 because of reduced traffic expectations.
According to Bob Lloyd, project manager and overall head of the Highways Department's major works section, attention at present is focused on the 5.2km long Shenzhen Western Corridor, a multispan bridge link across Deep Bay into mainland China which is being carried out in joint venture with the Chinese authorities. Ove Arup has the detailed design contract for the Hong Kong side viaduct and two cable stay bridges, each around 300m span.
Construction begins next year as does a highway connection to this corridor, the elevated dual three lane Deep Bay link.