It has long been known that drivers adjust their speed according to the design of the road they are on; that's why when speed limits are reduced people don't alway slow down. Planner Jeff Speck has been studying this for years, and wrote in Citylab about the things that affect how we drive:
On city streets, most drivers ignore posted speed limits, and instead drive the speed at which they feel safe. That speed is set by the cues provided by the environment. Are there other cars near me? Is an intersection approaching? Can I see around that corner? Are there trees and buildings near the road? Are there people walking or biking nearby? And: How wide is my lane?
When people drive faster there are more accidents and the accidents are more severe. When lanes are wider they can support fewer alternate uses. To summarize:
When lanes are built too wide, many bad things happen... In a sentence: pedestrians are forced to walk further across streets on which cars are moving too fast and bikes don’t fit.
Now Jeff Speck has teamed up with illustrator and game animator Spencer Boomhower of Cupola Media to show what Bike Portland calls "one of the simplest principles of modern transportation planning: the fact that we can make a lot of big improvements to our streets using nothing but paint." This one is showing what happens when you go from 4 to 3 lanes, which is not so simple; this gets very political. In Toronto, it cost about a million bucks to pull out a lane and put in bike lanes and then have Rob Ford and Denzil Minnan Wong undo it all and put it back in. This one is a hard sell.
Here's what happens when you convert three lanes to two. This is easier; I can see this happening on one-way streets as shown here, without a lot of complaint or disruption.
But here is the classic, the wider 12' lanes reduced to 10'. The cars don't lose much and will probably be a bit slower; there is now room for a bike lane, albeit the dreaded door lane type. It also shows the parking lane being narrowed a foot, which does not take into account that people either do not know how to park or don't even bother trying; most of the time I have to pull way out for some big SUV or pickup that is halfway into the bike lane. But this is still an improvement over the situation in many cities, including Toronto where I live.
I do not have enough experience in them to say if two-way cycle lanes like this are an improvement over the door lane bike lanes; I don't ride as fast as kids and couriers and worry about a lot of passing in a tight space.
But it's terrific that people can actually use these illustrations to see that hey, it's not so terrible to give up a few feet for cyclists and pedestrians.