Twin Cities Streets for People

<< update in procgress - full study is attached as PDF >> 

From the study:

Conventional traffic engineering would not question the assumption that "safer" and newer roads reduce fatalities. However, this type of approach tends to ignore behavioral reactions to safety improvements that may off-set fatality reduction goals. For example, if a two lane road is expanded to four lanes this could potentially reduce the riskof head-on collisions but may also result in many drivers travelling at higher speeds, potentially leading to no gains in safety ...

The underlying engineering hypothesis is that road infrastructure "improvements" will reduce both fatalities and injuries. However, it is not found that this hypothesis can be supported. Results actually tend to suggest the counter-intuitive hypothesis that these type of road "safety improvements" actually lead to statistically significant, though small, increases in total fatalities and injuries, all else equal. This result has also been suggested by other recent research using aggregate safety data ...