Q: Some years ago, you said you like the lane life in cities like Shanghai and Beijing, because such lane communities look like villages but have urban convenience. Has Shanghai, Beijing or any other major city in China strengthened the lane life?

A: Both Shanghai and Beijing have taken measures to stop the rapid decline of lane life. They haven’t been obviously increased. But they certainly put in place ways of conserving that aspect of life, finding ways to reuse the hutong and linong environments in a manner that is commensurate with modern circumstances.

Q: There’s a saying that few policy makers, especially mayors, in China understand traditional Chinese architecture that always sought to blend human living with nature. How do you think China can balance its modernism with traditional architectural ideas like feng shui, which you once called common sense?

A: It depends. For example, I’ve known some mayors who have stories that support traditional forms of development but I understand the nature of the question. I think as far as tradition is concerned, the most important aspect from a Chinese perspective is, let me back up and say, look, we think about traditional forms of architecture.

 Q: Could you give Shanghai some suggestions as to how the city could have the best of both worlds when it comes to urban designing?

A: I actually think Shanghai is not doing a bad job in combining new with old.

If I look at even projects like Xintiandi, for example, I think the fact that there is an attempt to really conserve the old in a proper way and to build directly next to it very contemporary architecture is the right way to go. I don’t believe that you should make fake traditional buildings.

Q: How has Shanghai done in terms of preserving wetlands?

A: The wetlands are very important, for example, the Dongtan Wetlands on Chongming Island. The idea of sort of fencing it off is a good idea.

What I worry about is that the bridge now going there makes Chongming Island very accessible to downtown, shall we say, Shanghai, which means there will be bigger development pressures.

Q: Shanghai’s population was more than 24 million as of 2013, up about 400,000 from a year before. Is population growth a big problem for the city, and for China’s model of urbanization?

A: I don’t really believe in population targets per se. I think you know cities grow to the size they grow because they grow to the size they grow. It depends on how that happens.

Obviously if the population grows very rapidly and exceeds the capacities of infrastructure, public services delivery and so forth, then there is a real problem. But if it doesn’t, I don’t think a population target per se really matters that much.

It’s a bit like densities. You know cities arrive at their own densities by way of a lot of forces that have to do with national and city economic circumstances and so on. They are as dense as they intend to be dense. If you think your city as a self-organizing system, it arranges itself, let’s say intelligently, in a manner that allows it to function well.

Q: In a mega city like Shanghai, traffic jams seem inevitable. Are there any solutions to solve the problem fundamentally, aside from expanding pedestrian and bicycle lanes?

A: If you take Tokyo, for example, about 15 to 20 years ago, it had about 250 percent over capacity. I remember it was terrifying for trains in rush hour because these guys would push you in.

Now they put in more and more lines — something like a subway line every three years. Now it’s much less crowded.

So you just have to keep pressing on and Shanghai, among most Chinese cities, probably has done the best job so far but needs to just keep going.

The other thing is multiple choice. You’ve got to concentrate on high rail, high-capacity mass transit delivery but also you ought to be investing in other alternatives, more local forms of transit as well — bus systems, smaller buses, providing for walkable environment.

Q: Quite a few young people in Shanghai say they cannot even afford a decent home to get married, except with their parents’ financial help. Do you think Shanghai’s housing price is reasonable and sustainable?

A: Shanghai as far as I can tell has got a speculative bubble of housing that is unreasonable and I doubt it’s sustainable.

And in fact quite a lot of buildings were built and were done to, shall we say, to appeal to the need for more affordable housing. For example, rules like 70 percent of all housing should be 90 square meters or less. I don’t think it’s a very useful thing because what happens when people want more space and if you got for example policy to limit space under the national affordability? That won’t be very useful. There should be much more rental space.

In New York City we have the micro units, 30 square meters or less. I’m not sure that’s a good idea, either. I would say it’s a sort of popular idea, especially for the younger population and so forth. But in many cases, they can be converted.

Probably a lot of these high-rise residential types which were built in the late 1990s and early 2000s in Shanghai are very difficult to retrofit. You should be building housing which has a certain kind of natural capacity to be retrofitted and to be resilient and to change shape and size within more or less the same building.

Otherwise you would have a very, very high replacement rate, which is extremely costly from a social point of view. I mean the replacement rate in China, apparently according to your official records, is something like 30 years. That compares to the US at about 70 or 75 years.

The reality in Manhattan, where I live, about 88 percent of all the structures were built more than 50 years ago. That’s not true here, for example.

Q: Many rural migrants to Shanghai are unwilling to return to their hometowns as mega cities like Shanghai can offer services and job opportunities unavailable elsewhere. Should China encourage the development of more mega-cities, or should it encourage smaller cities to flourish?

A: Hukou system needs to be seriously addressed because a lot of these migrants coming to the city don’t have access to social services, don’t have access to education.

In the US and many other countries, we don’t worry about where you are from, and I think that’s right. You don’t worry about where you are from, who you are and what you can do.

The problem of the hukou system is that you automatically worry about where you are from and you don’t have the same privileges as other people. I think that’s a difficult situation.

The way I think mega cities all work, for example, you look at this Shanghai in relationship to the Yangtze delta.

Sure it’s a mega city. There are other cities, like Suzhou, Nanjing, Hangzhou, etc. And there are a lot of smaller communities. The region needs to see itself as a well-connected network in which different urban areas within it at different scales perform different functions and have different comparative advantages and they are for different purposes. Not the same purpose.

Q: Worldwide, there are several metropolitan areas like New York, Tokyo, Paris, London, Mumbai and Shanghai. Are they good for a nation’s economy and environment? Do you foresee new metropolitan areas in China and the rest of the world in the future?

A: I’m a New Yorker. I live in New York. I have lived there for 25 years. I think the answer for that is “yes,” very well so.

New York is very intense — more intense than Shanghai. It’s a quite well-managed city.

Certainly under the Bloomberg administration, it’s done very well, especially in terms of environmental amenities.

There are issues with respect to income inequality and so on but it’s vastly improved since the 1970s or 80s, when I first went there.

Most of the growth occurrence in China comes where there is already something there. Expectation that suddenly in the desert or somewhere a city of millions of people appears is not very likely.

Q: Nowadays, security is our top concern since mega-cities are targeted by terrorists or criminals on many occasions. How can mega-cities prevent such tragedies?

A: New York has got surveillance everywhere, got all kinds of national security apparatus at work.

We maybe got in the situation where citizens are complaining about the state spying on us.

But to have foolproof security you have to have very, very high levels of intelligence, counterterrorist intelligence, counterterrorist capacities to operate.

They are invasions, there is no doubt about it, of private life. So there’s always a balance back and forth.

But heaven forbid we have another 9/11. Heaven forbid you have tragedies here in China.

But I think cities have to balance how much surveillance they do in counterterrorist activities with private rights.