Two recently published English-language books on China’s wooden bridges make significant contributions to our understanding of this important, yet understudied, genre of Chinese architecture.1 An estimated three thousand covered bridges still survive in China, more than anywhere else in the world. China’s Covered Bridges: Architecture over Water provides an engaging and informative introduction to the most remarkable bridge types and individual examples among them. Woven Arch Bridge: Histories of Constructional Thoughts, in contrast, focuses on one subset of Chinese bridges located in a mountainous region in northern Fujian Province and southeastern Zhejiang Province, in China’s southeast. Inscribed in 2009 by UNESCO as a form of intangible cultural heritage, extant woven arch bridges number only around one hundred, of which the earliest known dates to 1625.

The authors of China’s Covered Bridges are among the world’s most seasoned experts on wooden bridges. Ronald G. Knapp, professor emeritus at State University of New York, New Paltz, has published more than twenty books on the vernacular architecture of China and Southeast Asia, including a 2008 monograph on Chinese bridges.2 Terry E. Miller has visited more than one thousand covered bridges in North America, three hundred in Europe, and one hundred in China, and has researched the topic extensively. Liu Jie, associate professor of architecture at Jiaotong University in Shanghai, has published seven books and many articles on China’s wooden bridges, specializing in bridge architecture in southeastern China. The authors have traveled to far-flung regions to study bridges, and their book is richly illustrated with their own photographs, as well as those of A. Chester Ong, a professional photographer who has collaborated with Knapp since 2005. The joint expertise of the authors enables them to cover a much broader scope in this book than would be achievable by a single author.

The author of Woven Arch Bridge, Liu Yan, is a lecturer at Kunming University of Science and Technology and a leading expert on China’s woven arch bridges. His technical understanding of these bridges, much of which was gained through years of fieldwork, is most impressive. Liu has participated in the construction of three woven arch bridges: two in China and one in Germany. On the two projects in China, he worked closely with master carpenters; for the project in Germany, he had gained enough skills to qualify as a “bridge master,” which meant that he was able to oversee the design and construction process himself. Liu’s practical experience allows him to tackle many questions about these complex structures that would be impossible to answer through a scholarly approach alone. For example, to better understand the structure of a nineteenth-century Japanese woven arch bridge known today only through historical design drawings, Liu created a 1:50 scale model of the bridge. The process of making the model enabled him to figure out that the beams in this bridge were likely fixed with iron nails rather than wooden joints, as was typical in China. Liu’s model is so sophisticated that it is now housed in the Deutsches Museum in Munich.

Both books adopt a cross-cultural perspective. The first part of China’s Covered Bridges includes a thorough introduction to covered wooden bridges in China, North America, and Europe—the only geographic regions worldwide where such bridges are found. This discussion is useful in that it helps readers understand what makes Chinese bridges distinctive. One major difference between Chinese covered bridges and those in Europe and North America is that the latter were built predominantly for the passage of vehicles, while those in China were mainly pedestrian bridges that doubled as places for shelter and socializing. In Liu Yan’s narrower typological focus, the global perspective emerges throughout the book in comparisons between woven arch bridges in China and those in Germany, Italy, Japan, Norway, and the United States.

The authors of these books do not attempt to trace linear developments in wooden bridge building over time; instead, they adopt a pluralistic approach whereby the independent origination of various structural types is highlighted. In their discussion of covered bridges in North America, Knapp, Miller, and Liu argue against the idea that immigrants brought covered bridge technology from Europe to the United States, stating that “American bridge building does not appear to be a continuation of European traditions but rather an innovative solution to the same challenges faced in Europe” (19). With regard to woven arch bridges, Liu Yan similarly counters previous claims that all woven arch bridges originated in China, arguing instead that they developed independently in different times and places. Rather than trying to trace the origins of woven arch bridges, Liu asserts, it is “of greater technical value” to ask how the idea of the woven arch structure came about in the first place (353).

The main challenge faced by builders of wooden bridges anywhere in the world was that of the span. The sizes of the timber members were naturally limited by the height of the trees. To meet the demands of a large span, shorter members had to be pieced together. In Europe and North America, the span challenge was most often resolved through the use of the truss, a rigid framework of triangularly connected timber members held in tension. The structural systems of most surviving wooden bridges in Europe and North America comprise a series of trusses, which enabled them to support very large loads. Not only were truss bridges extremely strong and sturdy, but they were also relatively convenient to build, because the frames could be made on land and then hung into position above the water. However, wooden trusses, especially their joints, were susceptible to damage from moisture. Therefore, roofs and siding had to be erected above the supportive deck for protection, which allowed the bridges to last much longer.

Across China, several different types of wooden bridges developed, including simple beam bridges, horizonal cantilever bridges, angled cantilever bridges, and woven arch bridges. Among all the Chinese bridge types, the woven arch is capable of the greatest spans, and, as Liu notes in Woven Arch Bridge, it is likely that the wooden arch structure developed as a “natural and reasonable solution” to limitations in timber length (308). One of the rarest and most remarkable bridge types in China is the angled cantilever bridge, in which a complex system of cantilevered logs project upward to create a polygonal arched deck. Only ten examples of this bridge type are known to exist today, and they can all be found in remote regions of the Bai minority in Yunnan Province in southwestern China. Before 2016, when the authors of China’s Covered Bridges began documenting and studying them, angled cantilever bridges were virtually unknown outside their region. Despite the great structural variety in Chinese wooden bridge construction, in no case was a truss framework ever employed. Unlike trusses, which could be built in advance on land, the wooden members in woven arch and angled cantilever bridges had to be assembled on-site and required complex falsework and scaffolding systems to support them during construction. Generally speaking, this made bridge building a much more dangerous profession in China than it was in the West.

In both the East and the West, the techniques of bridge building were closely related to the construction of roofs, since bridges and roofs had to deal with the same span challenges. Like bridges, wooden roofs in Europe were usually built with truss frameworks, and it is therefore not surprising that some of the most famous European bridge-building families also specialized in roof trusses. As Liu Yan explains, in traditional Chinese architecture, roof construction was instead handled by means of a corbelling system, in which horizonal members of increasing length are laid atop one another so that each beam transfers the roof load to the one directly below it. Although triangular-frame roof structures were common in architecture of the Tang dynasty (618–907) in China, they cannot be considered true trusses because the individual members were not held in tension. After the Song dynasty (960–1279), the use of inclined structural members disappeared altogether.

Why the truss never developed in Chinese architecture is a fundamental question, which Liu addresses in an important discussion in his conclusion. He postulates that the answer lies in the complex wooden joints used to link the horizontal and vertical members. Much more so than the joint types used in Europe, those used in traditional Chinese architecture connect the members tightly together, which creates a rigid framework so structurally stable that a truss is unnecessary.

Both books identify Chinese bridge building’s associations with ritual and religion as a unique feature. As in house and temple construction, the most important rituals revolved around the dong, the topmost beam in the structure. The first step in the bridge-building process often involved planting a tree decades in advance or, if that was not possible, carefully selecting a tree from which to harvest the dong. The tree was then felled and processed in a ritualized manner and covered with a red cloth until it was used. After the dong was successfully positioned (a process known as “raising the ridge pole,” shangliang), a religious ceremony involving offerings of food and drink was conducted. Completed bridges functioned, in part, as temples, with shrines to local or Buddhist deities placed in their centers facing the oncoming water. Like all traditional buildings in China, bridges were believed to have the power to affect the fortunes of the local populations and were thus constructed and decorated in ways that would bring good luck.

Chinese bridges also played important economic roles. Especially in mountainous areas, such as the Fujian-Zhejiang border region discussed by Liu, bridges connected isolated villages to one another and to the outside world. Thus, bridge building was closely linked to transportation flow and, by extension, to the local economic situation. Liu convincingly theorizes that the construction of woven arch bridges in this region began only after the fifteenth century, following the arrival of peace brought about by the government’s prohibition of silver mining, which had contributed to centuries of unrest. The newfound stability in the region led to economic and commercial developments, resulting in greater need for roads and bridges. Still, it was the relative geographic isolation of this mountainous area that enabled the woven arch bridge tradition to persist for so long, without succumbing to modern influences. This was also the case in Europe: in remote areas in Norway, woven bridge technology continued into the twentieth century, even though the more convenient-to-build truss bridge had been in use for centuries in more developed parts of Europe.

Both books address the topic of funding, explaining that bridge construction was usually financed by donations from various local individuals or groups, and bridge maintenance relied on charitable contributions. Local genealogies highlight the involvement of prominent families in the building and repair of covered bridges. Donors who contributed particularly large sums had their personal names and the names of their hometowns inscribed in large text on a prominent bridge beam, while the names of those who donated lesser amounts were inscribed on smaller beams. Liu Yan points out that a huge variety of place-names can be seen on bridges located at crucial traffic junctures, “indicating the power and influence of the bridge in the transport network of the time” (133).

The folk traditions associated with bridge building in China do not belie the technical sophistication of the bridges themselves, a fact that Liu conveys particularly well in Woven Arch Bridge. He describes in detail the traditional building techniques of the woven arch bridge, including the methods of siting the bridge, selecting the materials and tools, constructing the scaffolding, calculating the dimensions of the members, determining the angles to form the arch, and deciding on the joint types. Liu identifies choudou (crossbeam ramming) as the most crucial step in the construction process, in which large mallets were used to pound the topmost crossbeams tightly into position to create a rigid framework. Liu provides a helpful step-by-step photographic guide to facilitate the reader’s understanding of the complex construction process. China’s Covered Bridges similarly presents a clear and succinct overview of woven arch bridge construction.

One of the most fascinating aspects of Woven Arch Bridge is its lengthy discussion of bridge-building families. Information on the builders is derived from inscriptions on timber members, project contracts, interviews with surviving carpenters, and family genealogies collected by the author. Each group of carpenter “families” actually comprised several families from a local area with different surnames. Because the profession was so dangerous, carpenters often did not marry or have children; therefore, multifamily involvement was necessary to sustain the craft lineage. Each carpenter family kept its own trade secrets, which resulted in distinctive approaches to the structures. Remarkably, by closely investigating elements such as the joint types or the angle of the crossbeams used in a bridge, Liu Yan can often determine which carpenter family built the bridge, as well as the experience level of the carpenters.

Despite their overlap in content, these two books differ considerably in their approaches. China’s Covered Bridges is broad in scope and presents the information in a straightforward and survey-like manner. Woven Arch Bridge is narrower in focus and takes a more creative and theoretical approach. The two books will likely also attract different audiences. With its informative text and spectacular photographs, China’s Covered Bridges is suitable for general audiences wanting to learn more about the Chinese bridge-building tradition. The hardcover format and large size, moreover, make it an attractive coffee-table book, inviting readers to peruse it again and again. Woven Arch Bridge, on the other hand, is denser and more technical, making it more appropriate for scholars who want a deep dive into the mechanics of timber-frame bridge construction. Full of original data, surveys, maps, and architectural drawings, all thoroughly analyzed by the author, this book also serves as an important reference tool.3

China’s Covered Bridges and Woven Arch Bridge not only greatly expand our knowledge about tangible bridge architecture in China but also contribute to our understanding of the intangible craft practices, social customs, and religious beliefs that were essential to the creation and meaning of the bridges. Even though timber bridges may not endure much longer into the future, the work done by these scholars will help to ensure that the bridges and their associated cultural practices are thoroughly investigated and documented for posterity.

1.

Earlier scholarship in English has been focused largely on the distinctive “Wind and Rain” bridges of the Dong minority in southwest China. See, for instance, Xing Ruan, Allegorical Architecture: Living Myth and Architectonics in Southern China (Honolulu: University of Hawai‘i Press, 2006); Klaus Zwerger, Vanishing Tradition: Architecture and Carpentry of the Dong Minority of China (Bangkok: Orchid Press, 2006); Li Xuemei and Kendra Schank, “Time, Space, and Construction: Starting with Auspicious Carpentry in the Vernacular Dong Dwelling,” JSAH 70, no. 1 (2011), 7–17.

2.

Ronald G. Knapp, Chinese Bridges: Living Architecture from China’s Past (Rutland, Vt.: Tuttle, 2008).

3.

Liu Yan has created a Chinese-language database of historical woven arch bridges along with an interactive map: Min-Zhe Woven Arch Bridges Database, http://w-bridge.wiki (accessed 18 Oct. 2023).