The architect and real estate economist Sibylle Wälty teaches at ETH Zurich and is also researching into the economical use of land in urban settlements. | Image: Sophie Stieger

Sibylle Wälty, what for you defines ‘city’ and ‘countryside’?

If you really want to see them as a pair of opposites: the countryside means a lot of motorised, individual transport due to people travelling long distances: to work, on everyday errands and to their leisure activities. The city, on the other hand, brings with it a high density of use and therefore offers the possibility of reaching all your important activities on foot within ten minutes.

But the reality in urbanised parts of Switzerland actually involves long commuting times by public transport, traffic jams and densely populated landscapes.

Developments in the main cities mean that their inhabitants are being relocated to the agglomerations and even to the surrounding areas, instead of more living space being provided in the cities themselves. The result is an unchecked growth of traffic over the past twenty years. We are a long way from achieving a healthy, dense residential environment – not even in the cities – where workplaces, utilities and leisure facilities can be reached on foot or by bicycle.

Is there an ideal city density?

In my doctoral thesis, I developed two criteria that would meet the legal requirements for the economic use of land. First, at least 10,000 people ought to live within a radius of 500 metres around a public transport hub. Second, and roughly within this perimeter, the ratio of residents to people in full employment should be two to one. This would create an average walking distance of ten minutes between home, work and leisure facilities.

How far are our cities from achieving this ideal density?

In recent decades, the decision-makers in our cities have done a lot to attract jobs, but have not been providing enough apartments for people to live in. People who live far from the city centres don’t always do so voluntarily. This also explains the consistently high demand for urban housing.

And this leads to high prices for apartments.

That’s because there are too few apartments to satisfy demand. Paradoxically, the building code and the regulations on usage often hinder sufficient housing construction in the city centres. To offer a comparison: theoretically, Zurich today lacks some 300,000 residents for the local labour market.

Did it used to be different?

The area along the Langstrasse in Zurich used to have a ratio of two to one between residents and full-time workers; today it is one to two. Urban planning has to allow for higher densities of use in areas that are well served by public transport. This can prevent motor traffic from continuing to grow – despite population growth – and it can help to call a halt to urban sprawl.

You argue in favour of the urban ideal of the 10-minute neighbourhood. Is this a realistic vision?

We need more ‘city’ in the city. In Bern, for example, the area around the Breitenrainplatz corresponds to this ideal. In Zurich, it’s the area around the Brupbacherplatz. What’s important is that urban planners should allow this kind of compactness of land use in the first place. They don’t have to tackle this problem with specific areas in mind. They have to consider whole suburbs. And it’s imperative that the residents are involved in the decision-making process.