Jeffrey Ferris

The Effect of Downzoning for Managing Residential Development and Density

Authors: David Newburn and Jeffrey Ferris
Report
Synopsis: This study analyzes the effect of a downzoning policy on both the rate and density of residential development using a difference-in-differences (DID) approach. Spatially explicit panel data on subdivisions are exploited to estimate average treatment effects for downzoned areas. Our results indicate that although downzoning does not significantly alter the rate of development, it does strongly affect the density of development. The lower density in agricultural zoning relative to the residential control area is only partly attributable to downzoning because, as our DID results indicate, it is important to control for baseline differences that exist prior to policy adoption.

 

Maryland’s Forest Conservation Act and the Impact on Residential Development and Forest Cover Change

Authors: Jeffrey Ferris and David Newburn
Report
Synopsis: We analyze the effects of a unique forest conservation regulation on residential development and assess the additionality in forest cover due to this regulation. We combine panel data on forest cover change from satellite imagery and parcel-level modeling on residential development, including residential subdivisions occurring before and after regulation adoption. Our results indicate that after introducing the regulation, there was a 22% increase in forest cover within subdivisions relative to the amount without the regulation. The heterogeneous effects of this regulation suggest that forest cover increased on average for parcels with lower levels of existing forest cover. However, parcels with the highest levels of forest cover continue to have significant decreases in forest cover, despite the regulation, thereby resulting in fragmentation in regions with the most intact forest cover.

 

Wireless Alerts for Flash Flood Warnings and the Impact on Car Accidents

Authors: Jeffrey Ferris and David Newburn
Report
Synopsis: Wireless alerts delivered through mobile phones are a recent innovation in regulatory efforts toward preparation for extreme weather events including flash floods. In this article, we use difference-in-differences models of the number of car accidents from days with government issued alerts for flash flood events in Virginia. We find that wireless alert messages for flash flood warnings reduced car accidents by 15.9% relative to the counterfactual with non-wireless alert protocols. We also use a regression discontinuity model to analyze hourly traffic volume data immediately before and after a flash flood warning message is issued. We find that traffic volume is reduced by 3.1% immediately following the issuance of a wireless alert relative to before the alert. These results imply that wireless alert messages effectively reduce exposure to hazards associated with extreme weather.