Yuyuan Station, an interchange station between Shanghai Metro Line 14 and Line 10, is located in the Yuyuan Garden and ChenghuangMiao (City God Temple) area of Shanghai, not far from the Bund, and faces the skyline of Lujiazui city landmark across the river. Therefore, Yuyuan Station is not only an important urban hub for public transportation but also a gateway for city sightseeing. This is why Shentong Metro decided to create an extraordinary public space after the completion of the basic structural construction.

Before we started designing, the stylistic elements of the Yuyuan Station were the subject of much public scrutiny. Many believed that the traditional Chinese building style should be replicated in response to the historic neighborhood of Yuyuan Garden and City God Temple. In such an urban historical district, no matter what kind of design, can not escape such a discussion.

Therefore, our first challenge was the symbol of form.

Shanghai is a city that embraces the world, and this Yuyuan area is especially typical: in addition to the ancient architecture of the Orient, there are also Western architectural styles such as the Bund, as well as modernist clusters of buildings on the other side of the Huangpu River. It would be too simple and hasty to just graft one certain element roughly.

Our approach is: utilizing the original structural colonnade and inserting arches orthogonally tangent to form a classic western cross arcade. The ceiling arch surface, formed by a series of curved projections of water waves, laps onto the columns like a wave of water. By fine-tuning the curves of the arches, we have the ceiling form fitting the flying eaves and winding sheds of Chinese roofs. They are facing downwards, which we call "the reflection of the eaves in the water".

This simple geometric logic not only integrates the columns with the roof but also blends Eastern and Western architectural elements. Interestingly, the subway tunnel at Yuyuan Station is beneath the Huangpu River, just as the watery ceiling suggests.

The choice of arch as the geometric prototype is also for practical reasons. In a space with limited floor height, we utilized the space of the arch to place larger pipelines on both sides, thus freeing up the net height in the middle. Under the same conditions, the net height of a normal ceiling practice is only 3.5 meters; after optimization, the maximum net height is 4.2 meters.

Even though the process and technology were well thought out from the beginning, the problems that had to be solved afterward were difficult. The ceiling system consists of single curved aluminum panels of different shapes, bent and spliced at different radii, giving a smooth three-dimensional curved effect. That's what I'm going to talk about, our second challenge was multi-disciplinary integration and parametric techniques.

The plane of the station is not a repeating network of columns, but a date pit shape. Because the subway tracks separate on the way in and merge on the way out, this means that the spacing, height, and piping conditions are different for each span of the column network, and it's never as easy as creating a standard unit and then duplicating it across several spans. The integration of piping and the assembly of complex irregular shapes at Yuyuan Station was made possible due to the parametric technology of digital twins, which allowed the shapes to meet the different conditions at each location naturally as flowing water.

The parametric model adheres to some basic constraints: for example, the minimum spacing between two rows of aluminum panels must be greater than or equal to the maintainable operating spacing; the curves must be aligned with the positioning of sprinkler points and light fixtures; and the unfolded shape of each panel must be within the square of the entire purchasable aluminum panel to be cut by the machine tool, etc.

Parametric models help generate component models that accommodate different column network widths and heights, decompose the spline curve into several arcs, and minimize the variety of different components. The digital twin system automatically unfolds curved aluminum panels, segments them according to the dimensions required for cutting, and sorts, classifies, and outputs them to CNC machines for cutting, bending, and field assembly. The parametric model also provides instant feedback on material usage data, helping us keep costs within budget.

Tens of thousands of aluminum panels with different radii and shapes, as well as GRG columns, nodes, and keels, were processed and installed orderly.

What puts the finishing touch on Yuyuan Station is the combination of curved flowing shapes and lighting which reveals our third challenge: light.

While above-ground buildings are spiritually infused and changing by the sun's light and shadows throughout the day, underground spaces have to rely entirely on artificial lighting. We wanted to utilize light to empower spirituality.

LED light strips are installed on top of each aluminum plate, and the lights are on the ceiling mounting plates which block the glare and halo the soft colors, forming a three-dimensional LED canopy. The pixel matrix composed of LED soft light strips, in addition to the preset effects similar to the rhythm of flowing water, can also be combined with holiday events to present different light effects. For example, it can have a festive red color for Chinese New Year and scatter petals effects on Valentine's Day and Qixi Festival, etc.

In my mind, a good urban gateway and public space is not just a spatial sculpture, but an interactive public art.

The opening of Yuyuan Station was on New Year's Day 2021 during the COVID-19 Epidemic, but this underground dance of streaming light was so popular that many people came all the way to get off at this station, stopped by, and took pictures.

The LEDs are capable of broadcasting any video stream and are opened up to the public to participate in shaping the light and shadow of the space at Yuyuan Station. I hope that Yuyuan Station is not a static sculpture, but a canvas for everyone to inject a continuous, colorful soul into the city's public space.

Good design to us, is always about multi-tasking and solving multiple problems in one form, while even better when it also creates new experiences. I believe we did that at Yuyuan Station.