There's a good deal of empirical evidence that narrower travel lanes are safer for everyone because they slow motorist speeds.
On a perceptual level, narrow streets just feel more inviting, writes Katie Matchett at Network blog Where the Sidewalk Starts. Matchett looked at Jewel Street in the Pacific Beach neighborhood of San Diego, which varies in width. She shows how, as it transforms from a narrow neighborhood street to a wide road for fast-moving traffic, Jewel Street becomes more forbidding for people on foot:
Here's what Jewel Street looks like when it's 30 feet wide, with parallel parking on both sides and a parkway between the sidewalk and street.
Notice that even with only a few scrawny palm tree for shade and relatively narrow sidewalks, the street still feels comfortable and "human-scaled." (It also feels safe to bike on, even without fancy bike infrastructure, because the narrow travel way forces cars to slow down.) I regularly see kids playing in the street here, using the roadway as an extension of their yard.
Here's Jewel Street a few blocks further down, with a 40-foot width. This would be considered the pretty much the minimum width for a street built today.
Even though nothing else has changed besides the width (arguably the parkway and street trees are even a little nicer), the street feels more "auto-oriented" and the neighborhood seems less inviting for walking or biking.
Then we arrive at this monstrosity, a few blocks further north. At a width of about 46 feet, the street allows for diagonal parking on one side -- but the awful design of the multi-family housing to the east precludes parallel parking on the other side of the street, making for an exceptional wide travel way:
Here all semblance of walkability has been sacrificed in the name of driving and parking. The parkway is gone, the sidewalk slopes awkwardly to allow cars to drive over it at any point, and there's not a street tree in sight. And then of course, there's the hideous design of the multi-family housing that lines this block. Particularly on the right, this street says to me, "Here is a place where cars live. If you're lucky, we might let some people squeeze in, too."
Elsewhere on the Network today: Broken Sidewalk says laws that ban impact fees on sprawling development undermine cities in more ways than one. The Urban Edge considers how Houston should rethink its urban design in the wake of the latest flooding disaster. And Biking Toronto shares survey results that show an overwhelming majority of local residents -- even people who don't bike -- support cycling improvements.