Traffic engineers need to do more research. Consider:

http://www.tfhrc.gov/safety/pedbike/research/current.htm

Where it states: “The National Bicycling and Walking Study goals are to: Double the percentage of all trips made by bicycling or walking. [and] Reduce the current number of bicycling and walking injuries and fatalities by 10 percent. These are potentially conflicting goals unless research intervenes to reduce the risk of bicycling and walking per unit of exposure…”

The real conflict is with motorized traffic, and the area of conflict is speed. Reduce motor vehicle speeds and you will “reduce the risk of bicycling and walking per unit of exposure.” But nobody wants to hear or discuss or do that — reduce motor speeds. End of story.