Q What advice would you give to cities trying to reclaim space from cars?

A My advice would be that these changes should be made based on documentation and information.

That means that the first thing that you should do is record how people are using the city today. Based on this, you could make an overview of where improvements could be made, where it would be most efficient or give the best results. So my advice really is to have the data. Do not just start blindly doing projects here and there.

Q Are gated communities and privately owned public spaces obstacles to the democratic role of public spaces?

A We can talk about two models. One is the open society, where you have access to the various parts of society. To me, "open" and "democratic" go together. In this open society, rich and poor, and various cultural or religious groups have access to the same spaces, can meet and realise that this society is made up of all these different types of people; and together, we are a nation.

At the other extreme is a totally gated society, where everybody lives in fortresses, and all communication is made by television, e-mails or whatever. This is totally different from the open society. I'm strongly against the gated community because I think that it is so much more valuable if we can make a wonderful city which everybody can enjoy.

Public spaces which are privately owned, like airports and shopping malls, can perform some functions of being a meeting place for people. But generally, there are much stricter rules for what you can do, and they also keep out people who are seen as strange or too poor. Publicly owned spaces have a much wider range of activities because they are governed by the police and the government, who put down rules on what is and is not allowed in this society. They are not governed by what is good or not good for business.

Q How do you find Singapore's public spaces, and what more would you like to see here?

A Boat Quay, Chinatown and Little India are some very interesting areas in Singapore. What I feel is that they are not linked in any convincing way. You can easily go to Singapore and overlook quite a few of these. So I suggest that an active policy be made to link these places in a better way - maybe a light rail going through the city.

The idea of having more pedestrian traffic underground is not very good. You are protected from heat and rain, but after 10, 20 or 30 years, these passages tend to be very uninteresting. There's so much more fun and enjoyment moving on the surface of the earth.

If you go to Orchard Road in Singapore, you see that you have much better temperature at the sidewalks when you have ample tree coverage. You can easily walk in the daytime in Singapore if you are careful with the vegetation. So don't push people underground, like moles, or even to the second level. They have done quite a bit of this in Canada and northern USA, which they regret bitterly now. Because it's very difficult to get the surface working again as a public space.

Q Do you think sky gardens work as public spaces?

A I think we need research on this so that it's not speculation and we can base it on real facts. Gardens in the sky provide fresh air and relief for those living or working in high-rise buildings. I suspect that they function as public spaces to a certain degree, but also that a good park at the ground level - easily accessible for all in the community, not just those who live in this high-rise - would be in most cases a much better solution.

Q Are cycling and walking viable mobility options in a tropical city like Singapore?

A In my dream, I see Singapore as the first city in the world to be car-free.

It's really stupid to drive cars on an island that is 50km by 25 km, and where people live so densely. If you are to expand from five million to seven or eight million people, you cannot rely on technology from Detroit in the US in 1905, which has given everybody four rubber wheels to secure individual mobility. That was a good strategy 100 years ago, but it's certainly not a good one for 21st-century cities, and especially not for Singapore, which is so confined and so condensed.

Singapore could be served by fantastic neighbourhoods where you walk and cycle short distances without getting too sweaty, with a very efficient public transportation system that links these neighbourhoods. You don't need cars at all in Singapore, in my opinion.

It would be really lovely if you start to analyse what would be a smart mobility strategy for an island city like Singapore. You could have much better neighbourhoods than the ones you have today, where schoolchildren have to climb up and down silly bridges to get to their schools. People would walk, cycle and use public transportation, and cars are used only for emergency services, people with disabilities and deliveries.

The promotion of walking and bicycling is more obvious in certain countries than others. In Copenhagen, we do a lot of bicycle-commuting because that keeps us warm, but that's not your problem. In Singapore, I see bicycling as something for small trips, to the train station or supermarket, and not to commute for half an hour in the heat. Bicycling can be used very differently in different climates.

• This is an excerpt from a longer interview piece appearing in the forthcoming issue of Urban Solutions, the biannual magazine from the Centre for Liveable Cities.