General Knowledge
John N. Ivan, Norman W. Garrick, Gilbert Hanson
Connecticut Department of Transportation
Published in
Submitted by
Related theme(s)
Road Safety, Rural Transport, Urban Mobility
All Regions

Designing Roads that Guide Drivers to Choose Safer Speeds



This report describes an investigation into whether or not physical characteristics of the roadway and the roadside environment are associated with actual vehicle running speeds, and how actual vehicle running speeds are associated with the occurrence and severity of motor vehicle crashes in conjunction with other roadway and roadside characteristics. Actual vehicle running speeds were observed at about 300 locations in urban, suburban and rural areas across Connecticut, at locations without horizontal curves or traffic control devices.
The findings demonstrate that through careful, intentional selection of roadway and roadside design elements, it is possible to influence the running speed of traffic on a road. It appears that drivers indeed take cues from elements of the roadway and roadside environment to decide how fast to drive and these cues are independent of the posted speed limit and other considerations that might be important to the community for reducing speeds. So the good news is that it is possible to influence drivers’ choice of speed through design of roadway and roadside elements; but the bad news is that many existing roads cue drivers to travel much faster than the posted speed limit and the community would like.