The city first needs to perform a traffic study to check the speed of vehicles on the block. In accordance with standard practice, the city uses the 85th percentile speed to determine if a speeding issue exists. This means that 85% of vehicles are driving at that speed or lower. If the 85th percentile speed is 28 MPH or above, the city will consider traffic calming improvements.
Some of the options considered in Royal Oak include:
- Speed humps
- Narrowing of travel lanes using striping
- Installation of median islands and/or bump-outs
- Mini traffic circles
- Raised intersections
The National Association of City Transportation Officials (NACTO) has a good summary of various options on their website.