Not Slow Enough? Traffic Casualties and New York City’s 20-Mph Zones

New York City’s Neighborhood Slow Zones (NSZ) program was created as part of an effort to increase pedestrian safety. This paper examines whether New York City’s Neighborhood Slow Zones (NSZs) are associated with reductions in traffic casualty rates for vulnerable users (pedestrians and cyclists), motor vehicle occupants, and total casualties. It employs a quasi-experimental, before/after research design with a comparison group. The paper first conducts a “simple” analysis (without controls), and then two controlled analyses that employ a difference-in-differences approach. While the simple analysis finds statistically significant reductions, the two analyses that include control zones do not find the NSZs to be associated with significant reductions in traffic casualty rates. Pedestrians and cyclists experienced the smallest reductions in casualty rates in all analyses, suggesting that the zones may be particularly ineffective for vulnerable users.

  • Supplemental Notes:
    • This paper was sponsored by TRB committee ANB20 Standing Committee on Safety Data, Analysis and Evaluation.
  • Corporate Authors:

    Transportation Research Board

  • Authors:
    • Hagen, Jonas Xaver
  • Conference:
  • Date: 2019


  • English

Media Info

  • Media Type: Digital/other
  • Features: Figures; Maps; References; Tables;
  • Pagination: 17p

Subject/Index Terms

Filing Info

  • Accession Number: 01698100
  • Record Type: Publication
  • Report/Paper Numbers: 19-00939
  • Files: TRIS, TRB, ATRI
  • Created Date: Dec 7 2018 9:46AM