Crash prone 'modern roundabouts'

[kphoger]

As much as we love to say that life is "invaluable", there is a number to use - and it's not very high. Same with injuries, more granular data on injuries would be interesting to flatten into financial value.  Same with extent of car damage.

And, see, I've been assuming that, when a department is tasked with "fixing an intersection", the reason is primarily to reduce the number of deaths and serious injuries that are occurring there.  So, if they do that, then I figure it's a success—even if other types of crashes go up.  That is to say...

— Too many traffic fatalities are occurring here.  Fix that.
— There.  Fixed.  Installed a roundabout.  Fatalities have gone down.
— But non-fatal accidents have gone up.
— That's what they told us to fix.

[kphoger]

Last, but not the least for me personally... I do have to cross the road near roundabout these days (thanks to certain people messing with parking arrangements, but whatever). And it IS tough. I am paying attention, I do make eye contacts, I can move fast. But it's just a high risk exercise.

This is a great point kalvado makes.  Looking at the safety within 250 feet of an intersection (whether it be a traffic signal or a roundabout) is great, but how does the intersection impact safety a 1/4 mile down the road for a driver trying to pull out of their unsignalized sub street? There are several traffic signals in the county i live that cycle 24/7 to create gaps in traffic to allow drivers to more easily exit nearby sub streets. A free-flowing roundabout corridor could potentially lead to more injury accidents mid-block.

First of all, that sounds awfully hypothetical—which is surprising to hear from you, who are usually interested in actual statistics.  I'd love to see an actual study of this sort but, failing that, let's just leave it as pure imagination.

Secondly, I agree that free-flowing traffic exiting a roundabout makes it more difficult for cross-traffic nearby.  You mentioned vehicular traffic coming out from a side-street, but I was thinking even more about pedestrian traffic trying to cross at a point mid-block nearby—especially those not crossing at a marked (and actually yielded to by drivers) crosswalk.

[tradephoric]

First of all, that sounds awfully hypothetical—which is surprising to hear from you, who are usually interested in actual statistics.  I'd love to see an actual study of this sort but, failing that, let's just leave it as pure imagination.

I agree.  I have had the thought that roundabouts may lead to more accidents downstream due to the free-flowing nature of roundabouts leading to fewer gaps in traffic, but i haven't dwelled on it seeing that it is so difficult to quantify.  A study that attempts to look at the impact would probably have some pretty big holes in it.

[kalvado]

As much as we love to say that life is "invaluable", there is a number to use - and it's not very high. Same with injuries, more granular data on injuries would be interesting to flatten into financial value.  Same with extent of car damage.

And, see, I've been assuming that, when a department is tasked with "fixing an intersection", the reason is primarily to reduce the number of deaths and serious injuries that are occurring there.  So, if they do that, then I figure it's a success—even if other types of crashes go up.  That is to say...

— Too many traffic fatalities are occurring here.  Fix that.
— There.  Fixed.  Installed a roundabout.  Fatalities have gone down.
— But non-fatal accidents have gone up.
— That's what they told us to fix.

Are there a lot of intersections in roundabout throughput range where fatal accidents are more or less regular events, not one-off-in-decade?

[tradephoric]

The US95 and US-50 roundabout in Lyon County, Nevada has been the site of 3 fatal crashes since opening in May 2020.  It's been averaging 0.6 fatal crashes per year since opening.

Silver Springs man identified in fatal crash on US-50 in Lyon County
https://www.carsonnow.org/05/29/2024/silver-springs-man-identified-fatal-crash-us-50-lyon-county

Fallon Man Dies in Crash Near U.S. 50 Roundabout in Silver Springs
https://www.2news.com/fallon-man-dies-in-crash-near-u-s-50-roundabout-in-silver-springs/article_5bcf26bc-a38c-598c-beed-40bde873699b.html

NHP: Mechanical failure to blame for fiery Silver Springs crash
https://www.kolotv.com/2021/05/29/fiery-silver-springs-crash-was-fatal/

The question is how many fatal crashes per year does the deadliest intersection in all of America average?  Is it higher or lower than 0.60 fatal crashes per year?

[kalvado]

The US95 and US-50 roundabout in Lyon County, Nevada has been the site of 3 fatal crashes since opening in May 2020.  It's been averaging 0.6 fatal crashes per year since opening.

Silver Springs man identified in fatal crash on US-50 in Lyon County
https://www.carsonnow.org/05/29/2024/silver-springs-man-identified-fatal-crash-us-50-lyon-county

Fallon Man Dies in Crash Near U.S. 50 Roundabout in Silver Springs
https://www.2news.com/fallon-man-dies-in-crash-near-u-s-50-roundabout-in-silver-springs/article_5bcf26bc-a38c-598c-beed-40bde873699b.html

NHP: Mechanical failure to blame for fiery Silver Springs crash
https://www.kolotv.com/2021/05/29/fiery-silver-springs-crash-was-fatal/

The question is how many fatal crashes per year does the deadliest intersection in all of America average?  Is it higher or lower than 0.60 fatal crashes per year?

Purely statistically, if you have a pretty busy intersection with 50k/day traffic, 6 drivers are going to die that year in crashes. If we're talking about in-and-out commute where people pass same intersection twice a day, it's 25k people and 3 fatalities per year.
That doesn't mean all 3 are in the intersection, that is over 12k miles average US driver goes a year.
So 0.6 is really a very high number, meaning just commute through 5 such intersections totally exhausts fatality statistics.   

[kphoger]

I'm having a hard time finding data for fatal accidents in Wichita, but the stoplight at 21st & Woodlawn, which had the fourth-highest number of accidents in 2023 (but the top one that's not along Kellogg) had 36 total crashes that year.  Kellogg & Rock gets about 100 crashes per year.  I wish I could narrow these down by fatalities, though.

[tradephoric]

According to the NHTSA Fatality Analysis Reporting System, there were 15 intersections in the United States with 7 or more fatal crashes between 2000 and 2019.  The most dangerous intersection was Lalor Street & SR-129 in Mercer County New Jersey with 9 fatal crashes.  That comes out to 0.45 fatal crashes per year (9 fatal crashes/20 years of data) which is lower than the 0.6 fatal crashes per year at the US95 and US-50 roundabout in Lyon County, Nevada (3 fatal crashes/5 years of data). 

Five years of data seems adequate to start comparing fatal crash rates, and it's pretty wild that an argument can be made that the US95 and US-50 roundabout is the deadliest intersection in America (based on fatal crashes/year) especially since roundabouts are suppose to reduce fatal crashes by 90% according to the FHWA.


https://www.fanglawfirm.com/the-deadliest-intersections-in-the-united-states/