What would New York city be without Central Park?

About Isabella Mambretti

Mambretti studied architecture at the “Politecnico di Milano”. At the end of 1990 she started working with Geographical Information Systems (GIS). Mambretti collaborated with Imago Metropolis, a European research project combining GIS and landscape visualisation. Prior to the research on ‘Urban Parks between Safety and Aesthetics’ she was already working on the development of software devoted to landscape visualisation, working with the beta test of the Amap software, which is a pioneer in high detailed visualisation of vegetation. “In 10 years the technology in landscape visualisation increased spectacularly, but I am still charmed by the technique of the software developed from the CIRAD Institute.”

Visualisation has not been used when exploring urban parks

In 2001, at the begin of my research at the ETH Zürich the combination of high detailed visualisation and conjoint analysis methods in landscape research was quite an unexplored field. Previous stated preference studies explored physical aspects measuring preferences for urban spaces; however, visualisation has not been used to the same extent in stated preference studies of urban parks. The task of conjoint analysis methods combined with visualisation was developed under the coordination of Professor Harry Timmermans, of the Eindhoven University of Technology.

“What would New York city be without Central Park?”

Together with Professor Harry Timmermanns, we explored an innovative way to apply conjoint analysis methods using visual simulation in order to catch and explain how observers build their preference for specific parks realities. Furthermore the research focused on how to experiment with the reliability of a stated preference experiment based on computer-generated images rather than text-based descriptions of park alternatives.

My dissertation is only a first drop in the research combing visualization and conjoint analysis methods. But we learned that the combined method of preference and visual simulation enables us not only to measure the preference of potential parks users, but to measure as well the role of specific attributes in people’s preferences. Our interest was not only to catch park users’ preferences collecting information about different visual perspectives and opinions about these spaces; but mainly to measure and explain how people build up their preference based on a visual description. I am convinced that the combination of visualisation in stated preference experiments offers a large field of research to be explored further.

What kind of images did you show the test group in the visual simulation of your study?

The images combine influential attributes selected from the contribution of previous research. We focused the research on different conditions of visual impermeability in 2 historical parks in Zürich. The images show selectively manipulated characteristics in the park scenarios, holding all other characteristics constant. In this way we could determine the influence of specific attributes, such as vegetation spatial arrangements, visual depth or seasonal changes.

The highest contrast between safety and aesthetic in similar conditions

We analysed the perception of personal safety, aesthetic quality considering the degree of variations to physical attributes (park characteristics) and visualisation (image characteristics). The dissertation was directed to measure the perception of safety and aesthetics on behalf of specific conditions in urban parks rather than to define the priority between the two. In our experiments we created several conditions of visual depth, and measured people’s reaction to the sense of entrapment and of concealment (for the personal safety) and their aesthetical perception. Interesting is that for example we found the highest contrast between safety and aesthetic in similar conditions. Lowest safety places, are on the other side the highest aesthetical evaluated. This result was expected because one question behind the research was whether one prefers dense, interesting, surprising park environments or safe, secure “deserted spaces” with little vegetation. This is still an open question, which on in my opinion involves not only new planned green spaces but also historical parks.

If you were to advice a city which is planning to build a new park in their city centre, what would you advice them to do? Are there any points which you would highly recommend and/or any which you would strongly discourage?

From this research I learned the importance to acquire broad consensus from the parks users and to increase the public participation in the planning processes. This is a lesson that was changing my quite selective attitude of expert versus not experts. I learned the importance to bridge the mutual knowledge. In research we hear a lot about interdisciplinary work, but I learned that the involvement of real parks users is essential for the success of a park. I also learned that park users like green space, vegetation, colours, flowers, rather than intellectual installations replacing the experience of green.
I think that there is a broad field that one can deepen, and I see a great challenge not only in the planning of new parks but also and rather in the actualisation of historical parks. The question is how to actualise historical green resources to that of a new park capabilities and users and to pride a solid response to the dramatic demand of safety, without eradicating the cultural heritage of these spaces.

In conclusion

I am convinced that we can learn from our history and from the good landscape architect of the past, nevertheless I am convinced that when planning for an urban park it is essential to define who are the specific park’s users, and to explore and invest resources to understand how the citizens would perceive and use the green spaces.

After almost 10 years in the research I left the academic world and now I am working in a private company in Zürich. Nevertheless, thanks to excellent scientists I had the chance to meet, I can say that the years devoted to this dissertation have been my richest experience. I am very thankful to Professor Harry Timmermans and Peter van der Waerden from the Eindhoven University of Technology, and Professor Harmen Oppewal at the Monash University in Sidney.

Elizabeth Winkel, EUKN