Press Releases

Press Release #08-061

Study of Park Slope ASP suspension finds minimal impact on parking and local traffic

Park Slope case study provides new data to inform future curbside parking strategies

A New York City Department of Transportation (DOT) study released today found that the eight-week suspension of alternate side parking (ASP) regulations in Brooklyn's Park Slope earlier this year had a minimal impact on traffic and parking conditions in that neighborhood. ASP rules were suspended in Park Slope from May 19 to July 14 as DOT replaced 2,800 street cleaning signs reflecting reduced street cleaning rules established by the City Department of Sanitation for Brooklyn's Community Board 6. Comparing data that DOT collected before and during the suspension, the study found that the amount of available curbside parking spaces during the suspension remained virtually unchanged from the neighborhood's already high level of occupancy. In addition, the study found that removing ASP regulations produced a slight decrease in traffic on mornings when the regulations are in effect. The study offers a unique perspective on traffic and parking and provides DOT with data to use as it seeks to develop new parking and curbside management strategies citywide.

Key findings include:

  • The availability of on-street parking did not change significantly during the ASP regulation suspension. The study found 98% occupancy when ASP regulations were suspended and 98% when ASP was in effect, indicating that on-street parking was saturated with or without ASP regulations.
  • There was no change in turnover rates of vehicles parked at the curb during afternoon and afternoon/overnight periods. (Longer-term turnover rates were not measured).
  • The percentage of observed vehicles registered in the local ZIP code increased from 37% to 49%, indicating that non-residents did not store vehicles in the neighborhood during the ASP suspension.
  • Traffic volumes increased slightly (19%) between 8 a.m. and 9 a.m. when ASP was in effect. There were no differences in afternoon or evening traffic volumes.
  • Residents were mixed on whether ASP suspension made it easier to find a parking space on weekdays: 47% said it was easier on weekdays while 31% said ASP suspension made finding parking harder. (The remainder said ASP had no effect.) Results were similar for weekends.
  • ASP suspension tended to either have no effect on how often respondents used their cars on weekdays (47%) or caused residents to use their cars less (39%).
  • 30% of respondents to an online survey said that curbs were less clean during ASP suspension, 45% said cleanliness was about the same, and 24% said that they didn't know or were unsure.

The report, which is available at, compares data collected in December 2007 and June and September 2008, using on-street license plate surveys and traffic counts to document changes in parking space occupancy, turnover and traffic volume. It also includes data from a Web-based survey of Park Slope residents that assessed their view of the effect of ASP suspension on parking conditions.