"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."
. . . A number of studies have been completed that blame wider lanes for an epidemic of vehicular carnage. One of them, presented by Rutgers professor Robert Noland at the 80th annual meeting of the Transportation Research Board, determined that increased lane widths could be blamed for approximately 900 additional traffic fatalities per year."This is a long article, that, among other things blames engineers' biases for not accepting this premise as well as state laws which mandate wider streets.
I haven't had time to do more research on it. I did find a few other sources that supported the basic premise including this 2007 DOT Study.
On high speed highways they argue for wider lanes which they say reduce lane departure crashes. But . . .
In a reduced-speed urban environment, the effects of reduced lane width are different. On such facilities, the risk of lane-departure crashes is less. The design objective is often how to best distribute limited cross-sectional width to maximize safety for a wide variety of roadway users. Narrower lane widths may be chosen to manage or reduce speed and shorten crossing distances for pedestrians. Lane widths may be adjusted to incorporate other cross-sectional elements, such as medians for access control, bike lanes, on-street parking, transit stops, and landscaping. The adopted ranges for lane width in the urban, low-speed environment normally provide adequate flexibility to achieve a desirable urban cross section without a design exception."Read it yourself. The author is passionate about this subject and has done a lot of homework. Then ask the next traffic engineers you meet what they think.
Thanks LL for the link.