Proposal for the implementation of green infrastructure at the Zurich Main Station
As the Zurich Main Station is in the city centre, thousands of visitors and passengers pass by on a daily basis. Many issues like the urban heat island effect, flooding or the loss of biodiversity will become more and more severe due to climate change. Thus, installing green infrastructure to prevent and tackle these issues is essential. Besides the ability to cool the surrounding area, allow for faster drainage, clean air and give animals new habitats, the proposed instalments give other ecosystem services which are discussed together with the main services in my proposal.
The following resources were collected and used in my project:
Interview Transcript with M. Ruckstuhl, the Head of the department for ecological support for large construction sites, nesting aids, building bird breeders of “Stadt Zürich”:
A.S.: “As the Main Station is not close to any larger parks, does it make sense to install green infrastructure to enhance biodiversity?”
M.R.: “The tram tracks leading away from the Main Station have a lot of green infrastructures already. There are many buildings that are part of the extended Main Station. I am not sure which buildings you mean.”
A.S.: “I am only considering the Main Station Buildings. I wanted to consider a green roof and birdhouses for example.”
M.R.:” At the moment this is a big subject. The UHI effect is a major issue and installing vertical and roof greenings to help cool down buildings is very helpful. Any vertical greening is helpful. Green roofs can be very helpful too. The thicker, the more do they bring about a cooling effect. An extensive roof would have 8 cm substrate depth and is the minimum and only cools in a limited way. An intensive roof would help much more with up to 15 cm substrate depth.”
A.S.:” I was wondering how such instalments help strengthen biodiversity.”
M.R.:” In a previous email you mentioned the wall lizard – The Zurich Main Station has the biggest wall lizard population in the whole middle part of Switzerland. Usually, they are endangered but they are abundant here. They also go onto roofs where we already installed structures to support them.
The blue-winged grasshopper for example can also be supported. This grasshopper lives in dry areas and is present in areas around the Main Station. This insect can be supported on roofs as well if the instalments are large enough. They have wings so they can get onto the roofs easily. Many wild bees such as sand bees and many other species can be supported as well. Sand bees like sandy substrates on roofs. It would be important to install some smaller hills on the roofs where the bees can dig into, build their nests and lay their eggs.
If water areas could be installed on the roofs, that would be really helpful as well. After strong rainfalls, these could retain some water such that not everything goes into the drainage system straight away and potentially lead to floodings. Such open waters on roofs can support dragonflies. In the area, there are a couple of dragonfly species.
Birds can also be supported with installing bird boxes for e.g. Alpine swifts if they are installed on a taller building. In the SBB area there also kestrels and peregrine falcons that settled and could be supported. For such species, these roofs can be very valuable as the birds can search for food there. Many species such as black redstart, common redstart can also be supported.”
A.S.:” Are those endangered species you mentioned?”
M.R.:” The wall lizard is abundant in the area but generally endangered. The blue-winged grasshopper is strongly endangered as well as the wild bees which all need open and quiet areas. Green roofs are perfect places to support such species. The common kestrel and peregrine falcon need food. With urbanisation, they have fewer areas to find foods and thus a roof with wall lizards is a perfect place for them to feed. The life cycle is really important in this case and is supported by such green walls.
Green walls are also amazing and important for the local climate and also here, animals can be supported. Even non-endangered species such as sparrows, spotted flycatchers and goldfinches love such instalments and could use them if additional bird boxes are installed as well.
A beech marten would also like such an instalment. The question is if this is desired.
Also bats need to be supported. For example the Kuhl’s pipistrelle from the south. Around 20 years ago they came from behind the alps and settled in the middle lands of Switzerland. They spread well here, especially in urban areas. These can be supported well with bat boxes for example.”
A.S.: “Are the bats endangered?”
M.R.: ” Bats don’t have an easy life generally but it’s also hard to know how many there are exactly. The Kuhl’s or common pipistrelle for example together with 10-20 different bat species are all endangered to some extend and need possibilities to build their nests. Renovations and new buildings destroy their old nest locations and we don’t really realize that.
Not only endangered species need to be supported. At the moment e.g. Sparrows are abundant. But with increasing urbanisation more and more nesting opportunities are destroyed. Nowadays, we know that the population of sparrows is decreasing. In Paris for example they are almost extinct in some areas. It is important not to only support endangered species. If you build a bird box for example you can’t really decide which bird will build a nest there. Often, the more common species inhabit such boxes but every year there is another chance that some endangered species will nest in an installed box. One can only give many different options and structures to many species, giving possibilities for different species to inhabit those instalments. As mentioned, small hills on the green roofs or dead wood can be very important and support insects such as wood bees and others. These additions allow for even more areas where insects can build nests and proliferate.”
The rest of the transcript is not listed as it is irrelevant for the scope of this project.
Email Interview with J. Schneider, head of sustainability for SBB estates / strategic developments:
1.Has SBB ever considered sustainability projects?
Yes, we have a lot of experience with outdoor and roof greening. This is practically always part of site development and construction projects. As an example, I am sending you photos of the near-natural green roof on one of our new buildings in Zurich Altstetten (Letzibach C project). We have also already done a few experimental things as for example a moss wall in a train station in Olten or a “city tree” (small green wall with seatings at the bottom) in Altstetten.
2. Does SBB have certain goals/regulations that support a “greening infrastructure” project? What would these be?
We plan and build according to DGNB. This is the leading standard for sustainable building. The municipalities, in particular, set binding requirements for roof and outdoor greening. The city of Zurich is one of the leading municipalities in this area.
3. Does the SBB own the main station building? Is the building protected from certain restructuring?
Most of the area, including all railway systems and buildings, is owned by SBB. Many buildings and parts of buildings are historically protected.
4. Do you know why the central station’s balconies are not open to the public? (If you look at the main station from Bahnhofstrasse, it would be on the right-hand side of the building)
I do not know that.
5. Are there any plans/data showing the stability of the various roofs? Do you know who I could ask about this?
We do not want to publish the statics plans externally. Just so much about it: We are currently planning to cover the “Bahnhofhalle” and the “Wannerhalle” with photovoltaics. That is statically just about possible. For green roofs or the like, I am very sceptical whether this can be done without complex and very expensive static reinforcements. Green roofs with substrate/soil and water are typically very heavy. Our historical building fabric is hardly ever designed for this.
The rest of the interview is not presented as it is irrelevant for the scope of this project.