Driving through the Syueshan Tunnel, which was opened to traffic in June this year, few travelers can share the feelings of Chang Lung-chun. "For me, it's like traveling in a tunnel through time, filled with vivid and bittersweet memories."
Chang is an engineer working for Sinotech Engineering Consultants Inc., which has advised the government on the Fifth National Highway, or the Taipei-Yilan Expressway Project, since the late 1980s.
Part of the 54.3-kilometer expressway, which links Nangang, east of Taipei City, to Suao in the south of Yilan County on Taiwan's east coast, this 12.9-kilometer tunnel running through Syueshan, or the Snow Mountains, is a transportation boon previously barely imaginable for Taiwanese. In the past, people traveling by car between Taipei and Yilan had to take either the highway circling around Taiwan's northeast coast or the treacherous mountain road switchbacking over the mountains separating the two cities. But today the situation is totally different.
"I used to have to spend two hours taking the mountain road from my home in Sindian [in Taipei County] to my friend's home in Suao. With the new expressway, it takes less than an hour," says Chen Chun-chang. Not only has the journey time decreased dramatically but the new route is considerably safer. The coastal highway has a lot of truck traffic, and the mountain road is not really safe. Free of sharp curves, the Taipei-Yilan expressway, now renamed the Jiang Wei-shuei Memorial Freeway, is obviously a safer choice. Unlike other routes, which have one tunnel with carriageways in both directions, the Syueshan Tunnel actually features two borings, each of which carries traffic on one direction only, making head-on collisions impossible. On top of this, no big vehicles can, at present, use the tunnel, which further ensures safety.
While the public talks about the benefits the Syueshan Tunnel has brought, engineers such as Chang and the hundreds of workers involved in its construction often think of the hardships, at times seemingly insurmountable, in the process of creating one of the world's greatest engineering marvels. Thirteen people died in the construction of the more than NT$20 billion (US$606 million) tunnel, including eight Thai laborers.
Twelve Times Harder Than Concrete
What made the tunnel such an odyssey was the extreme geological conditions of the Snow Mountains. Even before work started, the project was seen as ambitious. But the reality was far beyond any expectation. According to Tseng Dar-jen, chief engineer of the Taiwan Area National Expressway Engineering Bureau of the Ministry of Transportation and Communications (MOTC), the MOTC began research on the feasibility of building a highway from Taipei to Yilan through the Snow Mountains as part of a study begun in 1982. "But it's impossible to have complete knowledge of geological conditions before excavation if the project involves a long tunnel running through high mountains," Tseng says. "Producing this kind of study would be very time-consuming and might even cost more than the construction of the tunnel itself."
The construction team mainly consisted of the National Expressway Engineering Bureau, which was responsible for making policies, Sinotech, and RSEA Engineering Corp. which carried out the excavation. It was hoped that more could be discovered about the geological structure of the mountain range before the excavation of the main tunnels, and for this purpose work began on a pilot tunnel in July 1991. The team soon discovered that the project was going to be far more difficult than they had expected. The culprit was the local sandstone, a brittle but very hard rock variety--12 times as hard as concrete--which made up much of the eastern section of the planned tunnel. It was not only the hardness of the rock that gave engineers headaches, but its richness in fissures containing large amounts of water. "The most serious hazard during tunnel construction was surges of water," says Chia Yee-ping, a geology professor at National Taiwan University (NTU).
"Basically, once a fissured zone was opened during the excavation, water previously trapped in the rock would flow through the fissure network toward the low-pressure tunnel," he explains. Water would gush into the tunnel, bringing with it large amounts of silt and rock debris, which would cause serious collapses. The most disastrous water flow occurred at the end of 1997 in the Taipei-bound main tunnel. Flowing at a speed of 750 liters per second, the water and the accompanying mudflow quickly buried a tunnel-boring machine (TBM) worth NT$1 billion (US$30 million).
The TBMs had never been used in Taiwan before three were imported from Germany for the construction of the pilot tunnel and two main tunnels through the Snow Mountains. In contrast to the traditional method of drilling and blasting, a TBM has the merit of using less human labor and causing less pollution in the tunnel. More importantly, it contributes to a higher excavation rate. However, in the face of very bad geological conditions, a TBM is of limited use.
Frightened Foreigners
As a result, the team, employing drilling and blasting and TBMs alternately, excavated the tunnels at a snail's pace. The job was so challenging that foreign experts balked at actually taking part in it, although they had been invited to Taiwan several times to give advice on the work. One French company with rich experience in excavating long tunnels even decided to pull out after it had agreed to work with RSEA.
Pressure on the construction team--and the government--built up as people began to doubt whether the tunnel could ever be finished--originally it was scheduled for completion in 1998. In response, the MOTC thought about changing the route of the expressway to avoid building such a long tunnel in such adverse geological conditions. It also thought about annulling the contract with RSEA and seeking help from international engineers. "But foreign builders were not necessarily able to cope with the difficulties either. Besides, they would charge a much higher price for taking on the job," Tseng says.
For now, the speed limit for vehicles in the tunnel is set at 70 kilometers per hour. (Courtesy of Taiwan Area National Expressway Engineering Bureau)
Things started to look up in the late 1990s when the geological conditions changed for the better as the excavation got closer to Taipei. Their accumulated experience helped the team improve their methods of excavation and prevention of water gushers at the same time. Another turning point came when the excavation of the second vertical shaft reached downward to the part connecting the middle section of the prospective tunnel.
There are three vertical shafts in total along the Syueshan Tunnel. All of them are used to ventilate the tunnels, the tallest one measuring more than 500 meters, higher than Taipei 101, the world's tallest building. But the team was more ambitious when they drilled the No. 2 shaft; they wanted to create new working interfaces from which workers could start to excavate the tunnel deep in the mountains, moving northward and southward at the same time.
Thereafter, the construction team made progress at a much faster pace, excavating two-thirds of the tunnel from 1999 to September 2004, in contrast with the initial one-third completed between 1991 and 1999. Inch by inch the world's fourth longest road tunnel, and the longest two-bore road tunnel, was finally completed and opened to traffic this year. The task was so tough that Encyclopedia Britannica classed it as amongst the world's most difficult tunnel engineering projects. The Discovery Channel also came to Taiwan to make a documentary on the engineering marvel, which was first broadcast in Asia in late August.
A Mixed Blessing
However, the tunnel has not been an unmixed blessing for everyone. The old routes to Yilan, because they were so long and demanded such concentration from drivers, allowed small towns to make a living providing rest stops where weary motorists could take a break and sample the local tea. For these communities the tunnel's opening has been a disaster. "Our business has been seriously affected by the tunnel. In comparison with the days before it opened, the number of tourists patronizing our shop has dropped by 60 percent," says Cindy Chien, a waitress working at a caf?on the coastal highway leading to Yilan. "In the past I saw people standing in front of the shop waiting until it opened. Now every day we have to wait for a while before we see the first customer."
And it isn't just the passing tourist trade that is withering. Tea growers in Pinglin, located at the northern end of the tunnel, have complained that their tea bushes have been affected. Like all other long tunnels, the excavation has caused the discharge of a great amount of water long stored in the mountains. According to Tseng Dar-jen, this is an inevitable consequence, and he adds that half a tonne of water per second is still discharged from the Syueshan Tunnel today, in comparison with the 1.2 tonnes per second from the 11,611-meter Mont-Blanc Tunnel between France and Italy. Farmers complain that the boring has resulted in a shortage of groundwater, leaving their crops parched. And even the hot spring hotels at Jiaosi, about seven kilometers south of Toucheng--the tunnel's eastern end--blame the tunnel when they found their springs reduced in flow.
Tseng, however, emphasizes that the tunnel has nothing to do with lack of groundwater. Plants absorb water from soil which is relatively shallow and the water content of which is related to rainfall and climate. Excavation deep in the interior of the range will have no effect on this. "Drought has affected tea bushes all over Taiwan, not only those in Pinglin," he says.
As for Jiaosi's problems, they owe more to the overdevelopment of hot spring hotels that share spring water. NTU's Chia Yee-ping in general accepts these explanations for the problems that face Pinglin and Jiaosi. But he has other concerns. "What really bothers me is the excavation's impact on the Feitsui Reservoir," he says. The concern was aggravated especially in 2002 when the water level of the reservoir providing water to the Taipei area reached a record low of 119 meters. While this was the result of extremely low rainfall that year, people also began to reflect on the excavation of Syueshan Tunnel which took place in the upper reaches of the Peishih Creek, a feeder for the reservoir.
"The excavation definitely has an influence on the flow capacity of the creek. The question is, how big an impact?" Chia says. According to studies by Sinotech, water discharge due to the excavation accounts for at most 0.3 percent of the total volume of water that flows to the reservoir and not all the water flowing through the mountain range will end up in the reservoir. But Chia has doubts about the current statistics, thinking that only long-term research--which is already being conducted--can decide the scope of the impact of the excavation.
Environmental Benefits
Despite the controversies, Chia would not say whether he is for or against the tunnel. "But I definitely oppose road construction along the mountainsides which would cause land and mud slides. That's much more environmentally unfriendly than construction of passages through the mountains," he says.
At least in some ways the tunnel should improve Taiwan's environment, as has been noted by transportation minister Tsai Duei. Shorter travel times means less use of fuel. Tsai estimates that, in comparison with the journey by the Taipei-Yilan mountain road, travelers using the new expressway will save gasoline worth NT$1 billion (US$30 million) per year, with greatly reduced emissions of carbon dioxide and carbon monoxide.
Moreover, the excavation of the tunnel has allowed Taiwan to accumulate valuable engineering experience and enhanced its competitive edge against foreign engineering companies. "We have significantly narrowed the gap between Taiwan and top-tier countries in the area of tunnel construction," says Tseng Dar-jen. "As mountains cover much of Taiwan, we'll encounter challenges in building long tunnels quite frequently. The completion of the Syueshan Tunnel guarantees that tunnels built in the future will be of a better quality than before."
The Syueshan Tunnel has, then, done more than satisfy the decades-old wish to shorten the distance between Taipei and Yilan and open up the island's east coast. Considering the benefits of the tunnel, there is no doubt that the extraordinary 13-year excavation struggle was worthwhile. "When things started to look up, and the excavation began to go smoothly, the gloomy atmosphere was soon gone," Chang says. "I'll never forget how happy and excited the construction team was when the final breakthrough of the tunnel came."