Higher or Denser?

A Debate Aided by GD on the Historic Urban Texture Conservation of a Typical Commercial Region in Shanghai

SUN Chengyu

Campus of Architecture & Urban Planning, Tongji University, Shanghai, PR China

apolloc@online.sh.cn

Abstracts:

The foreign concession period from 1840s to 1930s is the birth of modern Shanghai. And its influence is so widely and deeply that the colonial character has become an important part of the city’s identity until now. As a witness of this period and the main city-growing-axis, Nanjing Road (Garden Road) is an epitome of the city, which was always the backbone of Shanghai, just following the Bund on the east and leading the city’s development to the west.

With the varied political, commercial and traditional reasons, the urban texture on the both sides of the road has its own special identity, which is an important grown footprint of this region, as well as an invaluable evidence of the foreign concession history in Shanghai. So, the conservation of its urban texture should be very carefully considered before taking any irretrievable action.

As a pity, three roads have been erased to transform the special crushed street blocks into a normal one with proper proportion and dimension for a designed skyscraper. Then a part of such a characteristic urban texture is being erased! The intention of such a brutal action is just the result of the inadequate consideration on the region’s context and the shortsighted economic pursuit of the floor area quantity in an instinctive way to go higher without any rational analysis!

As an architect the author believes the quality is the life of quantity. In this case, concerning the urban regulations and the existing commercial pedestrian environment, good quality means a continuous shopping interface and a human scale, all which would be decided by Density rather than Height. So, between the two options to increase floor areas he prefers being denser.

Then with a VB program “HOD” coded according to the GD concept, the author planned four experiments in four circumstances, for each one to generate 100 samples according to a different set of construction volume parameters. Based on the several typical samples out of the 400 samples a visual analysis and comparison were conducted.

Finally, the author proved that being denser was more sensible on this region, which could have enough floor area as the market demand, altogether with the benefits of the urban texture conservation, longer continuous commercial interface, acceptable sunshine around, better city image and scale no matter on the street or from the sky.

I. The Introduction of the Site

A. The Location

The site is located at the north side of Nanjing Rd, which is the top commercial pedestrian region in Shanghai, even in China since 1840s, when the city began its modern life [1]. In figure 1, we could see the location of the city Shanghai in China, and the location of the road in the city, the both drawn in dark black. In figure 2, the site is red-masked. The area of the site is about 50,000 square meters.

Figure 1

Figure 2

B. The Growth of the Region

1. The Forces Composing the Urban Texture in the Region

a) The Political Force

The process of a strategy called “Construction beyond boundaries” [2] wove the city since its colonial period. In the figure 3, the above zone in yellow is the British concession, the below in blue is the French zone, both setting out from the Bund. The colonists just got the permission to settle their homes along the Bund from the Tsing Dynasty after the 1840s war. To expand their region, the British built new houses along Nanjing Rd. from the east to the west as their living and commercial axis. At the same time, they “offset” this main axis to the both sides in a very short distance offering cheap houses to the local people without the local government’s permission. Initially the local government didn’t notice such small construction process. With full filled residents living in this region supported by the urban facilities offered by the colonists, the British got the tacit permission to expand their concession to the north and south, which is called “Construction beyond boundaries”.

As a part of colonial history, the growth of the city is the result of the expanding forces of the foreign countries, during which the streets’ patterns of the Tsing Dynasty were broken into pieces and reconstructed by the strong western politicians.

Figure 3

b) The Commercial Force

The main developing axis Nanjing Rd. got its unique commercial position in Shanghai naturally. The value of the interface between buildings and streets became an obvious aspect for the developers to consider. With the born proportion of the crushed street blocks as the results of the “Construct beyond boundaries” the developers could pursue the maximum continuous commercial interface in a given region as showed in figure 4. And actually the north and south interface of the street blocks in this region became the top commercial streets of the city even the country at that time. The land price was known as “One inch square one inch gold bar”.

Crushed Street Blocks Normal Street Blocks

Figure 4

c) The Traditional Force

The concept of Feng Shui, which means the location of anything would bring the owner different fortune has a deep influence on all the construction of Chinese people. It is why the buildings always face north or south never the east nor west. The developing of the city Shanghai was also guided by it as a mixture of the western planning and the local tradition.

2. The Special Urban Texture of the Region

The combination of the above forces wove the special urban texture on this region around Nanjing Rd as we could see in figure 5. The street blocks on the both sides of Nanjing Rd. are crushed, while the blocks away from it are stepping into the normal proportion, which is something like the tree’s growth rings from the dense to the loose. All these urban textures recorded the growth of the city since the colonial period, which is regarded as the birth of modern Shanghai.

As the conservation result the old multi-story commercial buildings are still standing there acting as the volume of the top commercial pedestrian region, while the new skyscrapers stand behind them. The processing urban revolution hasn’t destroyed these old buildings because of the good shopping atmosphere they providing which the skyscrapers can’t. Looking at the figure 6 we could find the situation of this region. The pressure from the high buildings is there. From the eagle views the region is like a valley with old low buildings in dense surrounded by new high buildings in loose.

Figure 5

Figure 6

II. The Crossroad in Front of Urban Planners

A. The Demands from the Booming Economy

The city of Shanghai is having an urban revolution based on a booming economy, which could be drawn from the huge urban construction amount. The investment on the urban construction in Shanghai from 1990 to 2000 is 310 billion RMB (equal to 38 billion USD). The total exchange amount of the real estate of the city in 2001 was beyond the whole Europe. And the increase is about 33% every year [3]. From all these figures we could imagine why we called Shanghai a world site nowadays. The developing model here is very simple, just destroying all the existing to build a brand new one. Such strategy is based on the demand from a tight construction schedule, which equals to the profit to the investors. So we didn’t have time to consider more on the way we are taking. Everything is just from our instinctive response. What we know best is, “We want good floor area as many as possible on a given site in a short time as soon as possible, all which could repay us the most.”

B. The Way We are Taking

With the thinking above, the investors helped by the designers found the easiest and the seemly infinite way to get floor area is to combine the crushed street blocks into bigger one with proper dimensions to build high buildings on it. Such process is under going now in our site. In figure 7 we could see three streets have been erased. Then the six crushed blocks have been combined to adapt the dimension of a new skyscraper. As a result, a part of the urban texture as an evidence of the city’s growing history has been erased.

Figure 7

C. Urban Complexity Beyond Two Options in Front of Planners

It seems inevitable to destroy the old urban texture to full fill the economic demand to build skyscrapers. But this decision is just based on one condition that the floor area demand could only be full filled by the skyscrapers which could always offer more floor areas than the multi-story buildings. So in front of us there are two options in urban development as shown in figure 8, to be higher or to be denser. As we know, on a given site building higher would definitely get more floor areas than building lower. But the real urban situation is much more complex. Another aspect “Density” would count a lot. For the reasons of fire protection and sunshine hours, the high buildings have to stand in a low density, while the multi-story-buildings could stand shoulder to shoulder in a very high density. Then with a different density, it would be very difficult to tell immediately which model, “higher but looser” or “lower but denser”, provide more floor areas. This is why we always provide 3 main figures as Total Floor Area, Density and Height Limit, when we give a development plan to a region. With these figures the further designers always have a very big design space, in which he could choose to go higher or denser both having the same construction volume. Here on this pedestrian site, it is obvious that the denser model could provide a better shopping atmosphere, much longer commercial interface, and better view from the bund than the higher model on the condition that the total floor areas the denser model could offer here could full fill the real market demand. If we could prove that, it will be a strong beat on the popular building-higher-model in Shanghai, and a good path to save the historic urban textures under the huge revolutionary pressure from the economy demand or just an excuse of a lazybones.

Figure 8

D. The Author’s Defense

The period of foreign concessions is at least one of the most important parts in the history of Shanghai, especially in the fields of the city’s construction development and the city’s culture. As a main growing axis, Nanjing road and the region on the both sides are the best clues to understand the city. Then the special urban texture in this region is a lively evidence. So the author believes that there should be no reason to erase such an important footprint of the city. To keep it and to full fill the demands from the booming floor area usage, the author tries to establish that to be denser but lower will be better than to be higher. To debate on that, he takes the following analysis, and tries to defense with iron evidence.

III. The Author’s Analysis Aided by GD Concept

A. The Usage of GD Concept

The concept of GD (Generative Design) is introduced to this analysis. The philosophy in front of us is revolutionary. The traditional design process is always abstracted as a loop of generating one solution following a careful evaluation. The quality of the solution in a limited schedule is decided by the amount of the loops. More loops would lead to better consideration on more aspects, which is always the foundation of a better solution. We always regarded that the two parts, generation and evaluation are the domain of human intelligence. But the GD concept frees the human brain out of the generation part instead of rapid computer generated solutions based on some rules, which we used unconsciously in design process in the past. Then the human brains can focus totally on the evaluation part. Actually the speed of one loop in the design process is greatly accelerated by the aide from the computer. Then with more loops we can raise the design quality. At the same time, the design process is becoming a selecting process. Maybe in the future, everybody could enjoy the design process with all the special complex rules and calculation done by a program [4].

With such a new concept, we could try to generate building boxes on a site according to any given parameters such as Total Floor Area, Height Limit and Density with the layout rules we used to apply on the site. Then the computer could generate hundreds and thousands of different solutions or we called them samples [5]. Let’s generate 100 samples for each set of parameters. From the view of statistics, more samples will lead to more accuracy [6]. One designer would give 1-5 different solutions to a site according to a set of parameters normally. Then 100-sample is enough to hold all the possibilities of street space forms on a building-box level (The “building-box level” is the premise of the following analysis, which means every building is presented as a box of the same volume). After we adjust the parameters as we planned in the following, we could get 4 sets of 100-sample which could present all the possibilities and features of the street space forms on a building-box level of the site in the planned 4 circumstances. Finally, we could do the visual analysis based on the features and representative models among these four 100-samples.

In the following we could discover that GD method offers us a path to the rational analysis on the space regulatory parameters in a decision-making stage while the most work could be done on the building-box level.

B. The Factors Considered in the Experiments

As we mentioned above, the real site situation is very complex. A pure form without the consideration on the other factors means nothing. From figure 9, it is clear that the buildings in the site have to conduct the relationship with the conservation buildings on the Bund to the east, the atmosphere when people shopping inside on the streets, the extent of the sunshine disturbance on the surrounding buildings, and the height’s up and down from an eagle view.

Figure 9

1. The Visual Disturbance on the Conservation Buildings

The government documents need the Bund to be visually protected. That is to say people should not see anything disharmony on the skyline of the Bund, when he stands on the other side of the river. In other words there is a height limit (for our site it is 24 stories) [7], near the bund being lower while away from it being higher. This could be controlled in the program to set different height limit. And the result could be examined by a 3D perspective view on the generated box models.

2. The Visual Harmony while Shopping along the Streets

The commercial atmosphere is usually effected by the proportion of the street width and the façade height, altogether by the scale and continuity of the street space. There are a lot of books to introduce the special figures, which are the results of experiments and observations. Not to be too dogmatism, we just adopt some rules not the exact figures. Usually continuous interface and WH proportion between 1:1 to 1:3 will be welcomed by the commercial pedestrian streets. Anyway, we have the 3D models. With the VR tech we could feel the atmosphere directly.

3. The Sunshine Disturbance on the Surrounding Buildings

The sunshine hour is a very important figure in Shanghai real estate market. And the disturbance on the other buildings always limits the design space in a great extent, especially in such a developed region with a very complex situation. So in this stage we just use a basic distance formula to keep the building density in the site.

4. The Heights’ Up And Down of the Region from an Eagle View

As far as the eagle view from the towers in Shanghai is concerned, we used the VR again to simulate the perspective views from several important towers such as Jin Mao Tower. It may be an exciting aspect for the governors to consider.

C. The Four Experiments Designed for the Rational Comparison

The 4 planned experiments (see Table 1) are based on the government planning regulations and the construction experiences with the premise [7] that in this site, the high buildings would have 18-24 stories; multi-story buildings would have 5-7 stories; for the high ones, “Density” has to be below 70% and “Floor Area Rate” has to be below 8; for the low ones “Density” has to be below 70% and “Floor Area Rate” has to be below 4.5.

Then the author generated 100 samples for each experiment (A-D) with the program HOD.

The operation steps are introduced in the following.

Step 1. Run HOD which is programmed in VB6 using the ActiveX interface of ACAD 2004 [8-10].

Step 2. Open the DWG file of the site containing the red lines and surrounding building boxes with the thickness representing the heights.

Step 3. Pick the red lines of the design region in a window selection.

Step 4. Setup the parameters such as Story Range (low & high), Density, Floor Area Rate and the others as shown in the figure 10.

Step 5. Click the button “Generate”. (“100 loops” was set in the program, so it will generate 100 different samples of the whole site with building boxes according to the above parameters in several seconds. All the results are placed in ACAD Model Space in another layer. Then we could check it conveniently.)

Step 6. Browse the samples and pick out 5 typical samples from each experiment to visually analyze in 3DMAX through several fixed cameras.

The figures 11.1-11.4 for A-D are a part of the eagle views rendered in 3DMAX. And figures 12.1-12.4 for A-D are the street views from the human views.

Figure 10

Experiment	A	B	C	D
FAR	4.0	4.5	4.5	8.0
Density	60%	70%	19%	38%
Stories	5-7	5-7	18-24	18-24
Notes	Keep the existing urban texture		Have to erase five streets

Table 1

Figure 11.1 Figure 11.2

Figure 11.3 Figure 11.4

Figure 12.1 Figure 12.2

Figure 12.3 Figure 12.4

IV. Conclusion

Based on the analysis of the generated samples the author found that:

First, it is impossible for the planners to keep both the skyscrapers and the existing special urban texture on one site. They have to choose one direction.

Second, the floor area limit of multi-story building is 225,000 square meters as in sample B (figure 11.2 and 12.2). At the same time the density is 70%, which could full fill the real market demand of 180,000 square meters [3].

Third, according to the conservation height limit and the FAR limit, the density of high buildings can’t beyond 38% as in the extreme sample D (in figure 11.4 and 12.4), which would lead to a shopping malls model not a pedestrian model.

Fourth, concerning the continuity as well as the atmosphere of the commercial interface and the relationships to the opposite buildings on Nanjing Rd. and the people walking on the pedestrian streets, the visual effect of the sample A and B (in figure 12.1 and 12.2) are much better than in sample C and D (in figure 12.3 and 12.4).

In summary, going denser is more suitable on this site, which could not only full fill the real market demand, but also offer the benefits of the urban texture conservation, better commercial atmosphere and human scale, or we say that it keeps the quality of this top pedestrian shopping region in Shanghai. At the same time, the author found that the proper parameters for this site is FAR= 4.0, Density=60%, Height=5-7 according to the samples, which could offer a good visual effect and 20,000 square meters.

Wish this conclusion could contribute to the urban construction on this site in future.

References

[1] Wang, Shaozhou, 1989, The Shanghai Urban Architectures, Jiangsu Science Publishing.

[2] Wu, Jiang, 1997, The Shanghai Architecture History in One Hundred Years, Tongji Publishing.

[3] Shanghai Economic Committee, 2003, The Real Estate Survey, Shanghai.

[4] William J. Mitchell, 1995, City of Bits, MIT Press.

[5] Goldberg, D. E., 1989, Genetic algorithms in search, optimization and machine learning, Addison Wesley Publishing.

[6] Feller, W., 1971, An introduction to probability theory and its applications, New York: John Wiley & Sons inc.

[7] Shanghai Urban Planning Committee, 2002, The Regulations of Shanghai Urban Planning, Shanghai.

[8] Holland, J. H., 1962, Outline for a logical theory of adaptive systems, Journal of the Association for Computing Machinery.

[9] Howard, Lee M., 1995, The GA-P: A genetic algorithm and genetic programming hybrid, IEEE Expert.

[10] Michalewicz, Z., 1996, Genetic algorithm + data structures= evolution programs, New York.