For the Peace of Birds

By Lei Chuang, Liu Xinhong & Zhang Qishan

Overspending nearly two hundred million yuan, China’s building the world’s first fully-enclosed sound barrier railway

Jiangmen, Guangdong Province. The Shenzhen-Maoming high-speed railway is under construction.

The main construction for a fully enclosed sound barrier designed by the China Railway Siyuan Survey and Design Group (hereinafter referred to as “SIYUAN”) was completed in December of 2017.The sound barrier runs 2.03 kilometers in length and is specially designed for the “Birds’ Paradise” 800 meters away from the rail. It’s the world’s first fully enclosed sound barrier for a high-speed rail.

Overspending 187 million yuan, more than 40,000 sound panels have been constructed to avoid disturbing the birds with the noise from passing trains

On December 15, we went to the construction site in the district of Xinhui in Jiangmen City of Guangdong Province. Peering from afar, an arched corridor about 20 meters tall over the rail sat over the rail—this was the fully enclosed sound barrier.

多花近两亿，建造全球首段高铁全封闭声屏障

广东江门市境内，深圳至茂名的高速铁路。

一段由铁四院设计、全封闭式声屏障主体工程，2017年12月完工。这一声屏障全长2.03公里的，专为800米之外的“小鸟天堂”而设。它是世界首例高铁全封闭声屏障。

多花1.87亿，铺4万多块隔音板让鸟儿听不到噪音

12月15日，笔者来到广东省江门市新会区施工现场，远远望去，只见一条高20米的拱形“长廊”盘踞在铁轨上方，它就是全封闭声屏障。

800米外，就是著名的“小鸟天堂”。那里是座约1万平方米的小岛，周围湖水环绕。岛上，榕树密布。那里，栖息着夜鹭、牛背鹭和小白鹭，共96种3万多只鸟，其中8种国家二级重点保护鸟类，15种广东省重点保护的鸟类，还有54种按照中日候鸟保护协定、中澳候鸟保护协定覆盖的鸟儿。

1933年，作家巴金先生来到这里游览，写出散文名篇《鸟的天堂》，“小鸟天堂”由此得名，并成为大型的天然赏鸟乐园。

“隔音板上怎么有这么多小孔？”笔者问。

“这是特殊的隔音板，厚度为8厘米，比普通隔音板薄4厘米，但隔音、防风的效果更好。”铁四院环工处总工程师王忠合介绍，隔音板分为三层，最里层打了很多均匀的小孔，让声音穿透到第二层；第二层为吸音层，将噪音最大程度吸收、消解；最外层为防风层，可以抵御14级台风。

“铁路通车后，声音传到‘小鸟天堂’核心区，比过去只增加0.2分贝，对小鸟休憩、觅食完全没有影响。”王忠合说，这段全封闭声障屏共使用4万多块隔音板，比普通的半封闭式声障屏造价高出1.87亿元。

耗时两年，50多人团队攻关破解多种技术难题

傍晚，笔者跟随铁四院设计人员乘船探访。清澈透明的湖水环绕着小岛，鸟儿们“叽叽喳喳”的，它们有的站在树枝上唱歌，有的贴着湖水嬉戏。

2014年8月，铁四院开始负责深茂高铁的设计，设计时速200公里，在江门境内经过“小鸟天堂”。中国环保部明确要求：铁路通过“小鸟天堂”区段时，要设置全封闭声屏障和遮光板，确保不影响鸟类的栖息与觅食。“高铁上建全封闭声屏障，在全世界还没有先例。”铁四院桥梁院副总工程师刘振标说，该院联合国内一些知名高校，组成50多人的专家团队，进行两年多的研究，最终解决了各种技术难题。

专家们发现鸟类休息、觅食，主要集中在东、西、南三个方向，因此将线路走向定在“小鸟天堂”北面，避免对其生活产生干扰；桥梁与桥墩的衔接部分使用橡胶，减少火车经过时产生的震动；反复设计屏障内外风力，最终敲定拱形声屏障抗风效果最好。

为了不影响鸟类的正常生活，噪声必须低于50分贝，全封闭声障屏安装后，高铁通过时传到“小鸟天堂”的噪音，降至49.3分贝，符合环保部要求。

这段全球首例高铁全封闭声屏障，填补世界空白，对推动中国高铁建设及走出国门具有重要意义。

800 meters away from here is the famous “Birds’Paradise.” It is a small island covering an area of 10,000 square meters and surrounded by a lake.The island is densely covered with banyan trees and is home to more than 30,000 birds of 96 species,including night herons, cattle egrets, and little egrets. Of all these birds, 8 species belong to the state’s Class II specially protected species, while 15 are specially protected birds in Guangdong, and the other 54 are included in the species covered by China-Japan Migrant Bird Protection Agreement and China-Australia Migrant Bird Protection Agreement.

In 1933, the famous Chinese writer Ba Jin (1904-2005), author of Family, came to this site for a visit and wrote a well-known article: “The Paradise of Birds,” which is where the island got its name “The Birds’ Paradise” and became a large natural park for watching birds.

“Why are there so many small holes on the sound panels?” I asked.

“This is a type of special sound panel. With a thickness of only 8 centimeters, just half of the thickness of an ordinary one, however, its effects of sound insulation and wind protection are better,”said Chief Engineer Wang Zhonghe from SIYUAN Environmental Engineering Design and Research Department. According to Mr. Wang, the sound panel is a type of three-layered board, with the inner layer filled with many holes of equal size to allow the sound to penetrate into the second layer. The second layer, being the sound absorbing layer, will absorb and dispel the noise to the maximum degree. The outermost layer is the wind-proof layer, which is able to withstand even a strong typhoon.

“When trains are running, the sound of the rail reaching the core area of the Birds’ Paradise will only be slightly raised by 0.2 decibels, compared to the past. It won’t affect the birds’ rest and foraging in the least,” said Wang Zhonghe, “In total, it took over 40,000 sound panels for this fully-enclosed sound barrier, costing 187 million yuan more than an ordinary semi-enclosed sound barrier.”

A team of over 50 experts conducted research work for two years to ultimately tackle various technical problems

On the evening of the same day, we visited the Birds’ Paradise with the designers from SIYUAN by ship. With crystal water surrounding the island, the birds were chirping happily, some were singing on the branches, while others were playing on the lake.

In August of 2014, SIYUAN embarked on the design of the Shenzhen-Maoming high-speed railway, which would pass by the Birds’ Paradise when passing through Jiangmen. Its designed speed reaches 200 kilometers per hour. So, the Ministry of Environmental Protection required explicitly that a fully enclosed sound barrier and sun visor should be installed in the zone of the Birds’ Paradise to ensure that the birds’ resting and foraging would not be disturbed.

“It’s unprecedented to build a fully enclosed sound barrier on the high-speed rail,” said Mr. Liu Zhenbiao, deputy chief engineer of SIYUAN Bridge Design and Research Department. To tackle the problem, the department allied with some famous universities in China and formed a team of over 50 experts. After more than two years of research, they finally overcame various technical problems.

The experts found that the birds resting and foraging sites were mainly concentrated in three parts of the island—that is, the east,the west, and the south. So they decided to set the railway route to the north of the Birds’ Paradise to avoid disturbing the birds’life; rubber would be used for the joints between the bridge and the pier to relieve the shake from a running train. After repeated measurements of the wind force both inside and outside the sound barrier, they decided on the arched sound barrier in the end.

In order not to affect the birds’ normal life, the noise levels must be lower than 50 decibels. With the fully enclosed sound barrier installed, when the high-speed train passes, the noise reaching the Birds’ Paradise is reduced to 49.3 decibels, meeting the requirements of the Ministry of Environmental Protection.

The world’s first fully enclosed sound barrier on a high-speed railway fills a void in the industry and will surely be put to use in other ways around the world. It is of great significance for promoting China’s high-speed rail construction and its overseas market. (Translation: Liu Jie)