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Remapping China’s morning commute with digital twins

China, the world's most populous country, takes public transit very seriously. As of 2020, China operated 233 urban rail transit lines in 44 cities, and according to the country's State Council Information Office, has vowed to completely modernize its transport system by the year 2035.

Transit stations in Changsha, the capital city of central China’s Hunan province, are of particular interest due to the high volume of passengers. In a recent survey, Changsha's 100+ transit stations ranked as #1 for average daily passenger volume, with numbers topping two million per day, or roughly 25% of the city's population.
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Changsha's busiest station is the Wuyi Square Station, a major transit hub housing 16 bus lines and two subway lines. On average, 280,000 people enter or exit the station each day. For scale, this is roughly the equivalent of the entire population of Orlando, Florida.

With so much activity, Wuyi Square Station has been singled out for a closer look at its passenger flow. With an eye toward maintaining and improving infrastructure at this bustling hub, the Changsha Rail Transit Operation Co., Ltd. recently teamed up with 51World and Hunan Xindatong, a company that specializes in transport solutions for the Hunan province, to create a digital twin of the station.

The digital twin is a faithfully created 1:1 model of the station’s entire underground world, connected to the real world via sensors. The simulation operation platform of Wuyi Square Station combines the technologies of digital twins, the Internet of Things (IoT), and artificial intelligence to realize the close integration of Wuyi Square hub station and digital twin space, making the connection between passenger flow, equipment, and management more intelligent.
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Passenger flow at its core

The Wuyi Square Station digital twin has two purposes, one pertaining to the present and another for the future. For the present, live data from sensors in the station track both human and machine movement, giving a picture of the current passenger flow and the efficiency of machinery, such as the arrival and departure times of trains.
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To simulate passenger flow, 51World uses its own SuperAPI and DST dynamic simulation technology to support user-defined passenger flow simulation tasks, answering questions about the volume of passenger flow it can accommodate, and whether there’s a need for passenger flow control in specific areas.
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The Wuyi digital twin includes a mechanism to alert management to any abnormalities in the station’s systems, such as an equipment malfunction. Management is able to review the scenario via the digital twin and determine the severity of the problem—or whether a problem exists at all—which reduces the cost and disruption of false alarms.

To inform future improvements to the station, the digital twin system also includes a crowd simulator that can be used to try out various scenarios, such as a congested platform or an emergency evacuation. The crowd simulator generates passengers of various ages and levels of mobility, then has them entering and exiting the station, and getting on and off trains, at a realistic rate. By setting parameters for both passengers and machinery, the digital twin system is able to simulate crowd behavior and evacuation conditions for a variety of scenarios.
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Unreal Engine’s Blueprint features, coupled with Marketplace plugins, greatly speed up 51World's production of scenes. For example, the tools can automatically generate elevators, which gives 51World the ability to rapidly develop scenarios while maintaining performance.

51World cites several additional Unreal Engine features as being essential to the success of the digital twin system: ease of use, especially for material editing; the ability to connect visual nodes to write complex rendering logic, resulting in a substantial increase in rendering effects’ speed of iteration; and delayed rendering technology, which makes post-processing extremely flexible. In addition, the Python API provided by Unreal Engine makes automated batch editing of scene objects a cinch.
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The resulting system is one that 51World calls a “benchmark for smart applications in rail transit hub stations”—but they haven’t stopped there. In the future, the Wuyi Square Station system will be equipped with a number of additional functions such as energy consumption monitoring and additional tools for passenger service and emergency management.

Other digital twin projects

51World is also known for developing a digital twin of Shanghai, China’s most populous city. Other projects include a smart city / digital twin of Tongling in China’s Anhui Province.

The company is dedicated to using digital twins in as many ways as possible to improve China’s infrastructure. For example, they recently developed a digital twin system for waterways called Three Smart Lakes under the direction of the Fuxian Lake Administration of Yuxi City. For this project, 51World replicated a total of nearly 3,000 square kilometers of Fuxian Lake, Xingyun Lake, and Qilu Lake along with surrounding watersheds, and built a set of ecological supervision systems to facilitate management and decision-making for these vital resources. 

51World also created a digital twin of Mawan Port, a busy shipping hub where thousands of containers come and go every week, to improve logistics and operation efficiency. For this digital twin, 51World recreated nearly one million square meters of the port area and 100,000+ shipping containers, then set up the system to drive real-world updates through IoT and a robust API interface. To manage a container, the port management authority can input just a few attributes—location, size, owner, and so forth—and a 3D object appears in the scene that matches its real-world component exactly, down to the color and logo on the container.

To learn more about 51World’s digital twins projects, check out the company’s YouTube channel.

Unreal Engine is a major component in each of these systems, helping 51World to create and innovate in the digital twins space.

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