In remote rural villages, Yang Lihui, an associate professor at Beijing Jiaotong University, has seen many oddly shaped "bridges": some are made of two utility poles covered with thatch and mud, trembling underfoot as people walk across; others are built from a few concrete pipes and get submerged when the river rises...
But these bridges are now a thing of the past, replaced by new bridges designed and built by Yang Lihui and her students. At the end of November, their seventh bridge is about to break ground and is expected to be completed before the Lunar New Year.
This bridge has a romantic name—Crescent Moon Bridge—and is located in Yueliang Village, Sandu Shui Autonomous County, Qiannan Buyei and Miao Autonomous Prefecture, Guizhou Province. Once the bridge is completed, the children of Yueliang Village will no longer have to wade through water to get to school, and it will also provide a convenient channel for the sale of local agricultural products and the development of tourism.
Over the past nine years, with the support of the "Mao Yisheng Public Welfare Bridge—Small Bridge Project" (hereinafter referred to as the "Public Welfare Bridge Project"), Yang Lihui's team has traveled across more than half of China, conducting field surveys and designs in places such as Jade Dragon Snow Mountain and the depths of the Daliang Mountains, committed to solving the "last mile" travel difficulties for local people.
Today, they are no longer fighting alone.
1
A bridge connecting theory and practice
"Can I build a bridge?" Four years ago, when Zheng Yuhan saw the registration notice for the Public Welfare Bridge Project, he hesitated. At the time, he had just turned 20 and was a sophomore at the College of Civil and Transportation Engineering at Hohai University, still struggling with the knowledge point of structural mechanics analysis in his textbook.
Today, zooming in on the map dozens of times, in the folds of the Qinling Mountains, there is a bridge connected with Zheng Yuhan's name. The bridge is called Ci'an Bridge and is located in Mingxing Village, Shiquan County, Ankang City, Shaanxi Province.
Although it is a small bridge only 18 meters long, it meets the travel needs of more than 3,000 villagers in nearby villages. What makes Zheng Yuhan even prouder is that local villagers told him that after its completion, Ci'an Bridge has withstood two floods and remains "unshaken," while surrounding roads and bridges have suffered varying degrees of damage.
If the national road transportation network is compared to the human blood circulation system, the roads and bridges scattered across mountainous and rural areas are like capillaries, affecting the safety of people's "last mile" of travel. According to incomplete statistics, there are still more than 100,000 "small and micro" bridge construction needs in China that have not been included in national financial plans.
More than 80 years ago, the renowned bridge engineer Mao Yisheng presided over the construction of the Qiantang River Bridge, the first modern large bridge designed and built by Chinese people themselves, becoming a milestone in the history of China's railway bridges. In 2011, the Beijing Mao Yisheng Science and Technology Education Foundation launched the Public Welfare Bridge Project, aiming to build safe bridges for children in remote and impoverished areas of China, and civil engineering students at universities became the youngest group of "bridge designers."
Since most bridge sites are located in remote mountainous areas with harsh natural conditions, the road to building bridges is not always smooth.
Yang Lihui recalls that during a survey in Funing County, Yunnan Province, just as the students were preparing to take measurements, a village official on the opposite bank suddenly waved anxiously. Before anyone could react, a rock weighing nearly two tons rolled toward the team with a tremendous noise. "At the time I thought it was thunder," Yang Lihui said. Everyone instinctively scrambled up the hillside on hands and feet. When the rock stopped, the road where they had been standing was already buried.
What surprised Yang Lihui was that such danger did not scare the students away; instead, they felt an even greater sense of responsibility. "No matter what difficulties we encounter, we must build this bridge well," one student present said to Yang Lihui afterward.
From river width and flow rate to bridge site selection and span, from pedestrian and vehicle traffic to village population and local residents' expectations for the small bridge... beside the stream, many students pulled out measuring tapes and set up rangefinders for the first time, carefully measuring every data point.
"The ability to transform knowledge that students need to design bridges is the transfer and application of interdisciplinary knowledge in structures, materials, mechanics, computers, water conservancy and other fields learned on campus," said Lei Xiao, an associate professor at the College of Civil and Transportation Engineering at Hohai University.
After collecting data and returning to school, the challenge had only just begun. Practical questions such as "what materials to use," "how much to control costs," and "how to complete realistic rendering" emerged one by one.
For Yang Jiaying, a student at the School of Civil Engineering at Southwest Jiaotong University, the process of designing a small bridge was a knowledge "rebirth." "Things I didn't understand when studying textbooks before now need to be thoroughly mastered," Yang Jiaying said. The design must consider bridge vibration, bending, effective load, ultimate load and other knowledge; in addition to ensuring safety, it is also necessary to consider the experience of vehicles and pedestrians crossing the bridge. Moreover, team members must search for and study current industry standards during design.
In order to design a safe and beautiful small bridge, Yang Jiaying and her team members spent the entire summer vacation "soaking" in the laboratory. Ultimately, they designed a steel structure bridge in the shape of a red ribbon for a village in Gulin County, Luzhou City, Sichuan Province.
"An accessible ramp was designed at the bridgehead," Yang Jiaying introduced. Considering that the local population is mostly elderly people and children, the small bridge also added functions such as pedestrian-vehicle separation and leisure platforms. "I hope that when local people walk across this bridge together, it can become a bridge of nostalgia carrying memories."
"Students have the opportunity to apply what they have learned to real projects and solve real social problems, thereby deepening their understanding and mastery of professional knowledge," said Chen Rong, vice dean of the School of Civil Engineering at Southwest Jiaotong University, when discussing the significance of the Public Welfare Bridge Project for talent cultivation. "The project also cultivates students' teamwork ability, innovative thinking and social responsibility, laying a solid foundation for their future scientific research or career development."
Over the past 13 years, the Public Welfare Bridge Project has built 27 public welfare bridges in 15 provinces including Chongqing, Jiangxi and Yunnan, solving travel problems for tens of thousands of villagers and thousands of students.
In order to attract more civil engineering students to participate, since 2017 the Beijing Mao Yisheng Science and Technology Education Foundation has hosted the "National College Student 'Mao Yisheng Public Welfare Bridge—Small Bridge Project' Innovative Design Competition," which has been held six times so far. More than 100 universities and nearly 500 teams have registered cumulatively, and many excellent design works have been successfully implemented after the competition.
A small bridge is like a bright moon, illuminating the children's path to school. "With this bridge, we no longer have to wade across the river and get our shoes wet; with this bridge, we are no longer afraid of fierce floods; with this bridge, we no longer have to brave the icy river water in winter; with this bridge, Mom and Dad no longer worry about me crossing the river..." a primary school student said at the completion ceremony of the first public welfare bridge in Pengshui County, Chongqing.
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A bridge connecting the individual and the greater good
If he had not participated in the design of a public welfare bridge, Yang Zhen, a master's student at the School of Civil Engineering and Architecture at Beijing Jiaotong University who grew up in a big city, would never have had the chance to get so close to rural areas.
In May this year, led by Yang Lihui, Yang Zhen and several classmates went to Yueliang Village for a survey. After a three-hour flight and more than an hour on a high-speed train, the team finally arrived at the county seat, then continued by car to Yueliang Village more than 100 kilometers away. The winding mountain road was sometimes broad and sometimes narrow, but the one constant was the endless circling.
By the time they reached Yueliang Village, it was already dusk, and the Miao village scenery before them swept away the team's fatigue. The unique stilted Miao dwellings were arranged in picturesque disorder, and endless terraced fields rose layer upon layer. Several children ran around the village; seeing the drone in Yang Zhen's hand, they gathered curiously, then scattered with a whoosh. As night fell, villagers played the lusheng to welcome the guests from afar.
During the three-day survey, team members visited Miao handicraft workshops, interviewed Miao village residents to understand their travel needs, and collected geographical survey data on site.
"Even engineering must be full of humanistic care. Only by understanding and respecting local traditional culture can the designed works truly satisfy the people," Yang Lihui said earnestly to the students on site. Therefore, in the bridge's appearance design, Yang Zhen and team members incorporated Miao batik craftsmanship into the railing design and embedded elements such as the moon and sun worshipped in Miao culture into the patterns.
In fact, being bridge builders with warmth is a principle that Yang Lihui's team has always adhered to. During one public welfare bridge site selection, in order to protect an elderly woman's farmland, the team gave up the best perpendicular bridge alignment and chose a skew bridge. Although this increased the design difficulty, it preserved the field the elderly woman had farmed for most of her life.
"Although this field is very small, it carries the memories of most of the elderly woman's life, and we could not bear to destroy it," Yang Lihui said. Protecting such a precious memory and emotion is far more important than any engineering convenience.
It is with this humanistic care that the teacher-student team of the Public Welfare Bridge Project gradually closed the distance with local villagers during in-depth visits. Facing language barriers, they cleverly used brooms, dustpans and other tools to vividly explain the bridge-building idea to villagers; an elderly man over 80 years old told them with deep emotion the story of the Red Army's four crossings of the Chishui River; and another elderly person in modest living conditions took out a bottle of beverage from deep in a cabinet at home, one he had been reluctant to drink, and handed it to them...
"The process of designing a public welfare bridge is not only a process of transforming theory into practice, but also a process of understanding people's conditions and livelihoods. Being able to use what we have learned to benefit the people of a place makes all the hard work worthwhile," Zheng Yuhan said with deep feeling.
Yang Zhen found that he gradually shifted from "what do I want to do" to actively thinking about "what can I do for the local area." He hopes to further promote and publicize the traditional handicrafts of the Miao village and donate schoolbags, books and other school supplies to local primary school students.
There is giving, and there is also harvest. Since the implementation of the Public Welfare Bridge Project, teachers and students involved in the project have witnessed with their own eyes the victory of the poverty alleviation campaign under the leadership of the Party. In Baoshan Village, Yulong County, Yunnan Province, only four years after Yang Lihui's team built the bridge, the road for vehicles had already been extended to the bridgehead, and more and more tourists were coming to visit the village; in Shiquan County, a number of township industries such as mulberry chicken farms, pig farms and organic fertilizer plants were newly built, and the bridge that Zheng Yuhan participated in designing is located exactly at a key transportation node; in Horqin Left Wing Rear Banner, Inner Mongolia Autonomous Region, after the Lianxin Bridge was completed, the price per kilogram of local agricultural and livestock products rose by 10 percent compared with before...
"'Poverty alleviation' and 'rural revitalization' are no longer brief phrases in news reports, but real scenes that come to mind one after another. We are both witnesses and participants in this great cause. For students, this is even more a vivid and lively 'great ideological and political course,'" Yang Lihui said.
This experience has also invisibly influenced students' career choices. In Yang Lihui's team, some students gave up job opportunities to stay in Beijing after graduation and chose to return to their hometowns to devote themselves to infrastructure construction, while one student even went abroad to serve the cause of global poverty reduction in Africa.
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An innovative bridge breaking tradition
Although small, the bridge is "complete in all its parts." In Lei Xiao's view, although it is not as complex in craftsmanship or as large in engineering volume as a major bridge, the process of designing and building a small bridge is likewise all-round training for students' knowledge, abilities and qualities.
A century ago, while presiding over engineering teaching at Southeast University, Mao Yisheng advocated reforming indoctrination-style teaching, promoted the integration of theory with practice in engineering education, and emphasized "practice before study, study while practicing." This concept has had a profound influence on the engineering community.
"Weak practical teaching links and insufficient interdisciplinary integration are shortcomings of current engineering education," Yang Lihui recalled her graduation experience more than 20 years ago, when she had the opportunity to intern on a construction site for a full month, eating and living with workers, whereas students today rarely have the opportunity to participate deeply in engineering construction. "The Public Welfare Bridge Project happens to provide a brand-new practical platform and a breakthrough point for reform and innovation in engineering talent cultivation models."
Today, on the basis of the Public Welfare Bridge Project, the School of Civil Engineering and Architecture at Beijing Jiaotong University has upgraded the "Weaving Bridges and Connecting Thoroughfares" education project to cultivate new engineering talents. Guided by project-based learning, students systematically learn and master knowledge related to bridge construction at school; in the practical stage, through deep participation in the entire process of actual engineering site survey, design, construction and completion, students' ability to solve real complex engineering problems is exercised.
At the same time, the "Weaving Bridges and Connecting Thoroughfares" project has carried out discipline competitions in related majors. Every year, fun competitions such as "paper bridges" and "spaghetti marshmallow towers" are organized for lower-grade students, selecting potential reserve talents for the project.
At Hohai University, the College of Civil and Transportation Engineering has combined the national first-class undergraduate course "Social Practice in Civil and Transportation" with the "Mao Yisheng Public Welfare Bridge" design competition, creating a talent cultivation model for civil and transportation majors in industry-characteristic universities that integrates professional courses, college student summer social practice, college student innovation training and national-level competitions. At Southwest Jiaotong University, the School of Civil Engineering, through cooperation with the Beijing Mao Yisheng Science and Technology Education Foundation and enterprises, jointly formulates project plans and guides students in competitions, which not only improves teachers' practical teaching ability but also promotes the transformation and application of scientific research results.
How to cultivate students' innovative ability is also a major challenge facing new engineering talent cultivation. "The Public Welfare Bridge Project provides a test field where innovative applications of new materials and new processes have sprouted and been implemented," Lei Xiao said.
For example, the He Bridge and Mu Bridge in Baoshan Village are located far from roads, and all transport must rely on human carrying, making the traditional reinforced concrete bridge scheme impractical. Facing the difficulties, the teacher-student team did not retreat. Through continuous investigation and design and pedestrian load tests, they finally settled on an assembled all-FRP beam bridge type. The superstructure of the bridge, more than 9 meters long, weighs less than 1 ton in total, and the disassembled components can all be easily carried to the bridge site by manpower.
In Xiushan County, Chongqing, Xingzhai Bridge made its debut as China's first thin-cover corrugated steel plate arch bridge. It is not only unique in shape and aesthetically pleasing, but also simple and quick to construct, with high value for engineering promotion.
Students have even more actively applied intelligent and information technologies to bridge survey and design. They used RTK equipment based on China's BeiDou satellite system to determine on-site bridge coordinates, used digital terrain model technology to generate three-dimensional geological survey maps, used drone aerial tilt projection technology combined with the bridge design process to build bridge BIM models, and imported bridge models into Twinmotion, 3DMax and other software to produce construction animations, making bridge models more intelligent and visual.
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Although he graduated years ago, Xu Honghao, a former member of the Public Welfare Bridge Project at Beijing Jiaotong University, still often pictures the scene when the small bridge was completed: children excitedly walking back and forth on the bridge, jumping and skipping, murmuring "Where is Beijing?" and "I want to go to Beijing." Today, he has gone to work in Uganda, but that small bridge and all the little things behind it have long been engraved deep in his memory. "I think if I have the chance, I will continue to participate."
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