I wrote this article several years ago but feel bumpouts are still a relevant and under analyzed area of traffic engineering. I still receive question from readers and clients about crosswalk bumpouts and their effectiveness and felt it was timely to share this article again. Have you seen an improvement in pedestrian safety through the use of crosswalk bumpouts? Send us a message – we’d love to hear from you.
Mayor Stu Rasmussen of Silverton, Oregon sent me the following email questioning the effectiveness of bumpouts (aka bulbouts or curb extensions):
I am wondering about what looks like a current fad in traffic engineering and was hoping you might have some empirical data to back up the current practice. Bulbouts or curb extensions are the current rage for crosswalk safety modifications. They are supposed to shorten the crossing distance and improve visibility of drivers and pedestrians for each other.
Definitely, the distance crossing active traffic lanes is reduced. To me that means that at a signalized intersection the cycle time can be accelerated because shorter distance for pedestrians means faster transit time.
At an uncontrolled intersection the benefits are not so clear to me. If a pedestrian approaches the active traffic lane on a bumpout, does a driver really know they’re going to immediately cross the street or could the pedestrian just get to the extended curb, stop, re-think their route, daydream for a while and then reverse course and wander off. All this time, the driver, if he/she is properly attentive, will be stopped while waiting for the ped to cross. After a few of these driver/pedestrian encounters it seems to me that drivers may become desensitized to the pedestrian – since it is entirely possible that no street crossing will occur.
Conversely, without a bulbout a pedestrian is obviously going to cross a street if he/she has actively stepped off the (non-extended) curb and entered the parking zone of the street. There is no question in a drivers’ mind of the walker’s intent, and the pedestrian is clearly visible at the edge of the active traffic lane as he/she approaches.
I am wondering if there is any unbiased empirical data supporting the addition of bumpouts to crosswalks – before and after studies of accident rates with and without the bumpouts – that would shed some light on this practice.
This gave me pause because I recommended bumpouts for an issue in Pine Island, MN (read about it here). They’re highly touted in pedestrian planning documents.
I spent some time digging and couldn’t find any research online about the effectiveness of bumpouts. I did find a mention in NCHRP Report 617 on crash mitigation measures that stated no research was available on the topic. So I posed the question to the ITE Traffic Engineers Listserv I’m on.
Dwight Kingsbury of the Florida DOT came back with this study from Oregon. The dataset shows positive results, but the sample size isn’t very big. I think I’ll stand on the side of bumpouts enhancing pedestrian safety, but more research would be nice to quantify the benefits.