Roundabouts, curb bulb-outs, and speed humps are all are forms of traffic calming, which offer promise if properly applied to curb speeding and some forms of aggressive driving. Pedestrians especially benefit from traffic calming. Traffic calming employs physical changes to the roadway, signage or operation changes, and can be thought of as a "silent policeman" enforcing speed limits where no law enforcement are present.
Traffic Calming Website
The Federal Highway Administration has financially supported the Institute of Transportation Engineers to develop a Traffic Calming Website in the interest of information exchange.
Analysis of Speeding-Related Crashes (PDF 594 KB)