Research 

Creating inequality in access to public transit? Densification, gentrification, and displacement. (with Michael Wicki and David Kaufmann) Environment and Planning B: Urban Analytics and City Science. 

Densification is a key concept in contemporary urban planning. Yet, there are widespread concerns about densification causing displacement and gentrification. This paper examines densification around train stations—a prevalent form of transit-oriented development (TOD) in cities with established public transit systems—in the Canton of Zurich, Switzerland. We assess the effects of densification around train stations on the socioeconomic population composition in these areas and investigate three different potential displacement effects. Leveraging 1.8 million linked person-housing unit observations for all individuals within our study perimeter, we provide a more nuanced understanding of densification’s effects on the population composition and displacement than prior research. Our findings reveal that even though densification increases the absolute number of low-income residents, it primarily benefits middle- and high-income households. Specifically, there is a decline in the share of low-income residents, attributed to the influx of younger high-income individuals. Moreover, incumbent low-income residents experience an increased risk of direct displacement due to housing demolitions. These outcomes highlight the limitations of TOD strategies in mitigating persistent socioeconomic disparities in public transit access, emphasizing the need for more comprehensive measures to address the challenges of equitable housing and public transit accessibility.

Making Housing Affordable? The Local Effects of Relaxing Land Use Regulation  (with Simon Büchler) Journal of Urban Economics

This paper examines the effects of relaxing land-use regulations on housing supply and rents at the local intra-city level. We apply a staggered difference-in-difference model, exploiting exogenous differences in the treatment timing of zoning plan reforms as identifying variation. Increasing the allowable floor-to-area ratio (FAR), i.e., upzoning, significantly increases the living space and housing units by approximately 9% in the subsequent five to ten years. This effect is stronger for larger upzonings, for rasters where zoning is binding, and where rents are high. Furthermore, upzoning leads to no difference in hedonic rents between upzoned and later-upzoned rasters. These results show that upzoning is a viable policy for increasing housing affordability. However, the effects depend on the upzoning policy design and take several years to materialize.

Media coverage: A Swiss city cut red tape and ended up with many more homes. It's a model for the US,  UCLA Housing Voice Podcast. 

Working Papers

Riding to Opportunity? The effects of Bogot´a’s cable car on experienced segregation (with David Kaufmann and Neave O'Clery)

How does access to public transit access affect low-income individuals’ mobility behavior and propensity to meet individuals from different economic backgrounds as they move throughout the city? We analyze the introduction of the TransMiCable, a cable car system in Bogota, which connected a low-income neighborhood to the city center and opened in late 2018. Using an event study design, we compare areas near the new cable car line to those near planned stations of a future line. Our analysis employs one year of granular GPS data from cell phones, over 80,000 points of interest from Google Maps, and block-level income information. Our findings indicate that the cable car’s opening significantly increased visits to commercially active lower-middle-class areas in Bogot´a’s center by approximately four visits per person per month. Better public transit also significantly increases visits to public and semi-public places within individuals’ own neighborhoods, potentially fostering local social connections. However, there was no significant increase in visits to high-income areas. The results suggest that improved transit access enhances mobility and strengthens social networks among low-income and lower-middle-class individuals. However, it does not increase meetings between low-income and high-income individuals in public places in cities.

Housing after redevelopment: Where and to what buildings do displaced residents move? (with Fiona Kauer and David Kaufmann) [R&R at Urban Studies]

Densification is often implemented by demolishing older housing stock, leading to the direct displacement of incumbent inhabitants. This paper studies how this redevelopment-induced displacement affects residents’ location and housing characteristics post-displacement. Using granular individual-level data of all residents from the Zurich region in Switzerland, we observe the redevelopment-induced displacement of 12,599 residents between 2016 and 2020. Our findings highlight the social stratification of redevelopment projects as they displace almost solely low-income residents. Displaced residents earned only 69.7% of the median income of all movers. Compared to all residents, those without Swiss citizenship have a substantially higher probability of displacement (9.6 percentage points). Regarding the location, displacement tends to occur between peripheral neighborhoods of the City of Zurich and its surrounding suburbs. We find that displaced residents from market-rate for-profit redevelopment projects move short distances but relocate to low-income areas. Additionally, they are more likely to move to old buildings (constructed 1945–1970), which are likely demolished soon, increasing the risk of repeated displacement. These findings highlight that redevelopment projects tend to increase spatial inequalities and predominantly affect low-income residents and those without national citizenship. Moreover, we show that housing assistance can mitigate some of the negative effects of displacement

Work in Progress 

Urban Densification through Vertical Extensions: Potential and Social Sustainability Implications (with Dominic Büttiker)

This paper examines the potential and social implications of vertical extensions—adding residential floors on top of existing buildings—as a form of urban densification. Using linked administrative data from 2010 to 2023 for Zurich and Geneva, we analyze the effectiveness of vertical extensions in increasing housing supply, their impact on existing residents, and the role of land use policy. We identify 1,068 vertical extensions and track 6,711 affected individuals. Our findings show that while vertical extensions contribute less to densification than replacement constructions, they allow a majority of longterm residents to remain—87% in Geneva and 42% in Zurich—thus helping preserve affordable housing. However, newly added units are typically more expensive, attracting residents with significantly higher incomes. Local policy plays a crucial role: Geneva’s regulatory framework promotes vertical extensions over demolition, resulting in three times more extensions than Zurich. Vertical extensions thus offer a socially sustainable but limited approach to urban densification.

Other Publications

Lutz, E., Kauer, F. & Kaufmann, D. (2023). Mehr Wohnraum für alle? Zonenplanänderungen, Bauaktivität, und Mietpreise im Kanton Zürich von 1996-2020. ETH Research Collection. [Media coverage: Tagesanzeiger, SRF, Blick] 

Büchler, S. & Lutz, E. (2021). The local effects of relaxing land use regulation on housing supply and rents. MIT Center for Real Estate Research Paper No. 21/18.

Lutz, E. (2020). The housing crisis as a problem of intergenerational justice: The case of Germany. Intergenerational Justice Review.