I’m really impressed by the quantity of discussion this website has generated. Hundreds of comments added by both convinced and unconvinced people show that people want to be involved in the city’s future even if they don’t agree what it should look like.
Rather than wading through the hundreds of comments I’ve tried to summarise what people have said so far in order to make the discussion more accessible. This is one of eight summaries covering various topics, including inspiration, vision and environmental considerations.
Personally I’d like to see this discussion moved into something like a wiki or drupal to make it easier to read and get the value from people’s opinions rather than them becoming lost in a seemingly endless stream of ideas. However, it’s not my content.
This summary was current as of 3:30pm, 19 March 2011.
The fundamental aspect of the project is to create a unique city center unlike anything else in the world that is functional and remarkable in its design for both inhabitants and visitors. It is hoped that it could be a relatively low cost way to create an iconic world destination for tourists and creative people.
Existing street level could remain the primary circulation route with nice wide avenues providing access to large below ground carparking lots, bus, tram and rail stations. Public vehicular access could be limited to this level, which would also be shared with the most utilitarian users who have no need for either sun or views.
The next level up could be occupied by those public users who require foot traffic, but again are not totally dependent on sun or views, such as you would find in a traditional mall, or large office spaces, sun could be brought into this level through clever use of roof lights, voids, etc.
Roof gardens above to create a park like atmosphere amongst which would be located the cafes, boutiques, hotels and apartments. This way rather than a series of interconnected roofspaces, and all its inherent difficulties you would end up with a layered cityscape resembling something more akin to a rolling hillside (on a conceptual level of course), with voids and pathways, pockets and promenades amongst which to enjoy the city.
Vehicular access to higher levels could be provided by either ramps or vehicle lifts to permitted vehicles during resticted hours to allow stocking of stores, etc, or alternatively central distribution points be located throughout the city to allow delivery of goods to and from stores. This layout could also facilitate a state of the art light transit system to deliver people around the city once they have parked their car (if they actually now need a car to go about their day to day business)
The fringes of this development adjacent to the river, etc would cascade down to the ground level providing 2 – 3 levels of prime positioning around the perimeter. Thus it would be possible to blend the city in with Hagley Park rather than having a single jump to to a 2-3 story high level that will shade the lower street.
Not all buildings must match this
Putting some buildings higher than the grassed areas can provide those areas with shelter or glass could be used to create shelter.
Could you walk barefoot around the CBD on grass without your feet ever touching the ground? By linking all the buildings together at the second floor level using bridges you create an entirely new public space. A network of covered walk-cycleways connect the various roof-tops together and slope down to other public spaces at ground level. This would alleviate some of the constaints put onto pathways by the grid pattern dictated by motor vehicles. Pathways could wind through the city like the Avon River, with lots of trees like Portland, Oregon. These bridges could be standardised in how they interface with each other and wouldn’t necessarily have to be made from concrete. Beautifully designed wooden bridges can easily handle foot and bike traffic. The system could be biased to be best for bike traffic to get around easiest. Amsterdam includes masses of right of way cycle tracks so that is it super easy and safe to get around without having to compete with cars. There could be places to store bikes at the elevated level and these could incorporate hire systems for bikes, motor scooters and segways. Lifts and escalators may be required for the less able to move between ground level and the elevated gardens. There are outdoor moving staircases in Barcelona but I think that their climate is drier than Christchurch and of course there will be energy costs for them. Although potentially they could be solar powered from the remaining roofs.
Some buildings would prefer to not have bridges to their buildings where they are trying to keep access to their employees only. Here they could put up a fence but they’d still need to provide a walk-way to connect to other buildings.
Faster transport could be provided by elevated monorails or free buses within the city or by extending the tram network.
There is the concern that removing foot traffic from the ground level destroys that retail environment and creates a people fee traffic dominated environment. Can you create an urban park above but retain the street as a multi-purpose environment?
The Green Stuff
An elevated garden that stretched across the flat roofs of a city would require significant organisation. How do you get all the soil up there if you can’t drive trucks on top of the buildings? Do you not even try and let the soil mature and develop over time? If the city’s roofs are covered in grass does that mean the CBD would hum with the sound of lawnmowers constantly? Or do you leave sheep to graze the grass for you? The tourist shops might be quite keen on that idea! What sorts of plants to you use? Bamboo species because they are lightweight and respond well to being contained and can create some privacy or native bush to encourage our native species? Do you grow different biomes on different rooftops and add community gardens and bird sanctuaries to others? Growing trees on top of buildings may be quite difficult but could you grow them beside buildings and wait for their branches to grow over the top in years to come? Or grow trees on earth ramps that lead up the sides of buildings as entranceways to elevated levels? Would planters be better and easier? Perhaps you could even return parts of the city to its natural swampy state? And amongst all this damp wet earth, can we keep the buildings underneath dry and warm?
Wind and Sun
Gardens are great on warm evenings but what about our cold rains and winds? Lots of wet grass, dirt and leaves may not be practical in the city center. In the summer, who wants to be on a roof in a north-westerly wind? You need shelter and shade in the summer and somewhere warm in the winter months.
Kids climbing on low fences along walking bridges is a worrying consideration. Plants could be used as walls or to hide fences so that people don’t fall off and also don’t have to look at fences all the time. Flower beds could be put in as obstacles between people and the edges of the roof.
Green roofs reduce storm water run-off by providing a buffer in the soil layer on the roof that holds the moisture and releases it more slowly. However, flat roofs and snow can be a dangerous combination if the roof is not designed for unexpectedly large snow-fall events!
Water that is collected would still have to be connected to spouting systems to avoid it building up over time. However this water might also be stored and then reused for irrigating the green areas, purified for drinking or collected into water features such as beautiful streams or waterfalls which may have added benefits for cooling the environment in summer.
How do you not make the ground level an overshadowed ghetto of rushing traffic and dark unattractive spaces? Is it possible to make both attractive to be in, although they may be different from each other? Can buildings be designed so that natural light penetrates through them to the bottom floors? If you have the option of leasing a building with a bright restaurant on top and two floors of dark offices below in the city vs one outside of the city with two floors of bright offices above and more dim ground floor, which would you prefer to spend your working hours in? Solar collectors or just plain good design may overcome these issues.
The Urban Heat Effect
Cities are hotter places than parks. The grass and trees in parks absorbs the sunlight and uses it’s energy in photosynthesis to create sugars. The result is that they output lower quality heat which we recognise when we move from the hot tarmac to the cooler grass. While both have been experiencing the same amount of sun light hitting them, the grass is cooler in summer to stand on and the air temperature also reflects this. Bringing more greenery into the CBD can cool it in the summer months, making it more pleasant to inhabit.
Doing it anyway
The thing that scares one person the most right now is the feeling of being “enclosed” and “surrounded” by buildings. A green space covering the CBD would remove this fear and provide an amazing space to show the world.