Theses Doctoral

Calming New York: An Examination of Neighborhood Slow Zones

Hagen, Jonas Xaver

Road traffic crashes are a leading cause of death and injury worldwide and in the US. In New York City, there are about 60,000 annual traffic casualties, including over 200 deaths. Area-wide traffic calming can improve traffic safety, pedestrian and cyclist comfort, and quality of life in neighborhoods (Elvik, 2009). This dissertation examines an area-wide traffic calming program, New York City’s “Neighborhood Slow Zones” (NSZs), in terms of environmental justice, traffic safety, and street design.
The dissertation consists of three distinct but interrelated empirical studies. The first one asks if the NSZ program furthers environmental justice in New York City. It examines the locations of the 28 zones in terms of minority and low-income areas, as well as the inclusion of these populations in the process that led to the siting of the zones. This chapter concludes that the NSZ program improves environmental justice in New York City, both because the zones are equitably distributed in poor and minority areas, and because the planning process that led to the siting of the zones was inclusive of these populations.
The second study examines the effectiveness of the zones at reducing traffic casualties. This analysis uses a quasi-experimental, before and after research design, with a treatment group (the Neighborhood Slow Zones) and a comparison group (similar zones that did not receive the treatment). The analysis does not detect statistically significant reductions in traffic casualties associated with the NSZs.
The final empirical uses a policy transfer approach to compare street design in New York City’s 20-mph zones to similar zones in London. London’s “Slow Zones” were found to be effective at preventing traffic casualties (Grundy et al., 2009), and were the inspiration for New York’s Neighborhood Slow Zones. This study analyzes the traffic calming devices transferred from the zones in London to those in New York. While street designs in London’s 20-mph zones included a robust implementation of traffic calming devices, New York’s NSZs had a much more skeletal implementation of these devices. This suggests that the nature of the transfer of street design from London to New York City contributed to the disappointing results of 20-mph zones in the latter city. Despite these findings, I argue that the NSZ program has had partial success.

Geographic Areas


  • thumnail for Hagen_columbia_0054D_14630.pdf Hagen_columbia_0054D_14630.pdf application/pdf 2.1 MB Download File

More About This Work

Academic Units
Urban Planning
Thesis Advisors
Freeman, Lance
Ph.D., Columbia University
Published Here
May 14, 2018