Crash prone 'modern roundabouts'

[kalvado]

I'd personally much rather someone doing three times the speed limit plow into a rock than fifteen people.

What if the person is a bus driver carrying 15 people?

If a bus driver carrying fifteen people plows into fifteen people instead of a rock, then that would be a total of thirty.  So, still better.

Social darwinism is, of course, not without merit h but is generally considered out of fashion.
In the case at hand, if more socially acceptable concepts are to be applied, 3 casualties  about $20 million - should be enough to fire a few people from DOT, hire some real engineers - even with recent $100k surcharge for H1Bs -  and rebuild approaches and the intersection from scratch using proper design. Moreso potential 15 people crash.

[tradephoric]

If a bus driver carrying fifteen people plows into fifteen people instead of a rock, then that would be a total of thirty.  So, still better.

A crash resulting in 15 deaths at a roundabout is better than 30 deaths.  Valid point.

[Scott5114]

I think it would be a little silly for someone to advocate for the removal of bridge dolphins because ships are damaged after hitting them.

[kphoger]

I think it would be a little silly for someone to advocate for the removal of bridge dolphins because ships are damaged after hitting them.

In this case, are the decorative rocks protecting a valuable statue or something?  I'm confused by the analogy.

[kalvado]

I think it would be a little silly for someone to advocate for the removal of bridge dolphins because ships are damaged after hitting them.

You seem to be confused by "remove guardrails and jersey barriers" thread

[Scott5114]

I think it would be a little silly for someone to advocate for the removal of bridge dolphins because ships are damaged after hitting them.

In this case, are the decorative rocks protecting a valuable statue or something?  I'm confused by the analogy.

It's protecting the town of Silver Springs.

[jakeroot]

I think it would be a little silly for someone to advocate for the removal of bridge dolphins because ships are damaged after hitting them.

In this case, are the decorative rocks protecting a valuable statue or something?  I'm confused by the analogy.

It's protecting the town of Silver Springs.

Jokes aside, I assume the rocks are to protect cars on one side of the roundabout from cars on the other side of the roundabout.

That said, we have gone through how many guardrail design eras...yet giant boulders are perfectly fine for roundabout central islands? Perhaps we could invent a deflective roundabout central island design?

[kalvado]

I think it would be a little silly for someone to advocate for the removal of bridge dolphins because ships are damaged after hitting them.

In this case, are the decorative rocks protecting a valuable statue or something?  I'm confused by the analogy.

It's protecting the town of Silver Springs.

Jokes aside, I assume the rocks are to protect cars on one side of the roundabout from cars on the other side of the roundabout.

That said, we have gone through how many guardrail design eras...yet giant boulders are perfectly fine for roundabout central islands? Perhaps we could invent a deflective roundabout central island design?

Its a wild west design. Next thing to come is red light cameras paired with machine guns. Anything to protect the city!

[tradephoric]

Car smashed in high speed roundabout crash
https://www.bbc.com/news/videos/cwydzg0235do

[kphoger]

Car smashed in high speed roundabout crash
https://www.bbc.com/news/videos/cwydzg0235do

Yes, technically that was a roundabout (though not a "modern roundabout" as the thread title says).  But he was going a zillion miles an hour, ran a red light, and T-boned cross-traffic.  How would that have been any better if it weren't a roundabout?

[jakeroot]

Car smashed in high speed roundabout crash
https://www.bbc.com/news/videos/cwydzg0235do

Yes, technically that was a roundabout (though not a "modern roundabout" as the thread title says).  But he was going a zillion miles an hour, ran a red light, and T-boned cross-traffic.  How would that have been any better if it weren't a roundabout?

It may not be a "modern roundabout" (starting to become an archaic term, to be honest), but it has the exact same design guidelines that US roundabouts could have used until the 2009 standards came about. Most early roundabouts in the US, especially multi-lane roundabouts, used either AU or UK standards.

[Quillz]

Car smashed in high speed roundabout crash
https://www.bbc.com/news/videos/cwydzg0235do

Yes, technically that was a roundabout (though not a "modern roundabout" as the thread title says).  But he was going a zillion miles an hour, ran a red light, and T-boned cross-traffic.  How would that have been any better if it weren't a roundabout?

It may not be a "modern roundabout" (starting to become an archaic term, to be honest), but it has the exact same design guidelines that US roundabouts could have used until the 2009 standards came about. Most early roundabouts in the US, especially multi-lane roundabouts, used either AU or UK standards.

Fair enough, but I think I echo what the other guy said: they were speeding and driving recklessly. I don't think a roundabout was going to make things much better or worse.

I'm in AK right now and they use roundabouts quite a bit in Anchorage and Fairbanks. I like them, they seem to do the job of slowing down traffic. You are supposed to yield to traffic in the circle, and drivers do seem to follow this. Quite a few junctions combine freeway off-ramps with roundabouts, mainly in Anchorage but also a couple in the North Pole area.

[tradephoric]

The perception shouldn't be that roundabouts are safe and traffic signals are dangerous.  You can have innovative traffic signal designs that have comparable safety benefits to roundabouts.

Farewell to roundabouts: why these new intersections are reshaping American roads and making driving safer
https://journalsofindia.com/news/farewell-to-roundabouts-why-these-new-intersections-are-reshaping-american-roads-and-making-driving-safer-50853/

The deadliest movements at intersections are left turns and crossing traffic. RCUTs tackle these by redirecting drivers away from perpendicular crossings, substantially lowering crash risk. According to the Federal Highway Administration, implementing RCUTs can reduce total crashes by up to 54% and crashes involving injuries by as much as 70%.

[Rothman]

I have yet to come across a DOT that is converting all signals to roundabouts.  NYSDOT's own policy is that roundabouts will be considered when considering improvements to a signalized intersection, but they aren't mandated.

Interestingly enough, I have heard a regional design engineer in NY bemoan RCUTs more than roundabouts...

[kalvado]

I have yet to come across a DOT that is converting all signals to roundabouts.  NYSDOT's own policy is that roundabouts will be considered when considering improvements to a signalized intersection, but they aren't mandated.

Interestingly enough, I have heard a regional design engineer in NY bemoan RCUTs more than roundabouts...

RCUT looks like an uncertain bet, with left right-angle merge without a ramp and a need to cross multiple lanes.

Honestly speaking, at some point there should be a realization that infrastructure can handle some over design capacity - but only that much. That includes roads, that includes airports, airspace above cities, power grid and what not.

[tradephoric]

Honestly speaking, at some point there should be a realization that infrastructure can handle some over design capacity - but only that much. That includes roads, that includes airports, airspace above cities, power grid and what not.

That's a good point about "over design capacity".  Carmel converted most intersections to roundabouts but they grade separated their heaviest traveled thoroughfares (Keystone Pkwy & US 31). By grade separating the heaviest routes, it really helped mask the limitations of roundabouts.  There is a practical limit where roundabouts just don't work so well anymore.  Their neighbors to the east in Fishers found that limit when they built the roundabout at 96th & Allisonville Road.  The rollout of that roundabout has gone so poorly that the city decided to scrap the plans for a roundabout at 116th & Allisonville which seems like a smart move.  Don't double down on a debacle. 

[tradephoric]

Half of the most crash prone intersections in Michigan during 2024 were at roundabouts.  Par for the course anymore.

MAP: Michigan's most dangerous intersections based on crash data
https://www.fox2detroit.com/news/map-michigans-most-dangerous-intersections-based-crash-data

1. 11 Mile Rd/I 696 @ Van Dyke Ave, Warren, 185 Total Crashes, 26 Injuries
2. 18 1/2 Mile Rd @ Van Dyke Ave, Sterling Heights, 162 Total Crashes, 12 Injuries (Roundabout)
3. Martin Pkwy @ N Pontiac Trl, Commerce Township, 151 Total Crashes, 9 Injuries (Roundabout)
4. Schoolcraft Rd @ Telegraph Rd, Redford Township, 137 Total Crashes, 26 Injuries
5. N Hamilton St @ Washtenaw Ave, Ypsilanti, 132 Total Crashes, 7 Injuries           
6. Orchard Lake Rd @ 14 Mile Rd, Farmington Hills, 109 Total Crashes, 5 Injuries (Roundabout)

[tradephoric]

Here's the most dangerous intersections in Michigan way back in 2015. Back then the 18 1/2 Mile/Van Dyke roundabout had 124 crashes (in 2024 it had 162).  In 2015 the Pontiac Trail/Martin Parkway roundabout had 186 crashes (in 2024 it had 151 crashes).  The roundabout at Orchard Lake/14 Mile didn't make the list of most dangerous intersections a decade ago, but only because the roundabout hadn't been built yet. 

The argument has always been people will get better at driving roundabouts as they become familiar with them.  That hasn't seemed to be the case in Michigan.

TOP 20 MOST DANGEROUS INTERSECTIONS
1. Pontiac Trail and M-5/Martin Parkway, Commerce Township (186)
2. Telegraph Road and 12 Mile Road, Southfield (132)
3. 11 Mile Road and Van Dyke Ave, Warren/Center Line (131)
4. 18 ½ Mile Road and Van Dyke Ave, Sterling Heights (124)
5. I-75 and Big Beaver Road, Troy (124)
6. Ford Road and Haggerty Road, Canton Township (116)
https://www.themichiganlawfirm.com/blog/2016/6/6/top-20-most-dangerous-michigan-intersections

[kphoger]

I'm currently teaching my eldest son how to drive.  Yesterday, I had him go through a roundabout for the first time.  About a block or two in advance, I started explaining what to do, but he interrupted:  "I know what to do at a roundabout now."  He yielded at entry and signaled his exit.

Single lane roundabout, though.

[jakeroot]

Half of the most crash prone intersections in Michigan during 2024 were at roundabouts.  Par for the course anymore.

MAP: Michigan's most dangerous intersections based on crash data
https://www.fox2detroit.com/news/map-michigans-most-dangerous-intersections-based-crash-data

1. 11 Mile Rd/I 696 @ Van Dyke Ave, Warren, 185 Total Crashes, 26 Injuries
2. 18 1/2 Mile Rd @ Van Dyke Ave, Sterling Heights, 162 Total Crashes, 12 Injuries (Roundabout)
3. Martin Pkwy @ N Pontiac Trl, Commerce Township, 151 Total Crashes, 9 Injuries (Roundabout)
4. Schoolcraft Rd @ Telegraph Rd, Redford Township, 137 Total Crashes, 26 Injuries
5. N Hamilton St @ Washtenaw Ave, Ypsilanti, 132 Total Crashes, 7 Injuries           
6. Orchard Lake Rd @ 14 Mile Rd, Farmington Hills, 109 Total Crashes, 5 Injuries (Roundabout)

Geez... Van Dyke Ave takes no prisoners.

It is interesting how some states will go head over heels to reduce or eliminate left turns, especially through installing DDIs. Yet in Michigan, none of the highest crash-rate intersections involve true "direct left" turns like at a standard signal.

A bit off-topic...but what in the world was going on at Hamilton/Washtenaw in Ypsilanti? Hard to believe that many crashes could occur at such a small intersection. I see they rebuilt it recently.

[TheHighwayMan3561]

Four buses got simultaneously stuck in a roundabout in Oslo and paralyzed traffic. Happy Thanksgiving, Trade.

https://www.facebook.com/photo/?fbid=779222081837393&set=a.353022557790683

[LilianaUwU]

Four buses got simultaneously stuck in a roundabout in Oslo and paralyzed traffic. Happy Thanksgiving, Trade.

https://www.facebook.com/photo/?fbid=779222081837393&set=a.353022557790683

I feel the need to point out this is the second time this happened.

[tradephoric]

Four buses got simultaneously stuck in a roundabout in Oslo and paralyzed traffic. Happy Thanksgiving, Trade.

https://www.facebook.com/photo/?fbid=779222081837393&set=a.353022557790683

Efficient!  Happy Thanksgiving to everyone.

[tradephoric]

Northside roundabout removed after $675K failure

[kalvado]

Northside roundabout removed after $675K failure

Looks like design is crappy to begin with. Someone heard about roundabouts, but never actually learnt about them.
So, as I said, no designer should be allowed to design one until they have at least 20 years of experience in roundabout design.