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Author Topic: Roundabouts and Semis  (Read 3827 times)

roadman65

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Roundabouts and Semis
« on: April 22, 2022, 10:05:35 AM »

I was talking to an ex truck driver who brought up an interesting point about the roundabouts. How small they are and how more challenging they are for semis to circumvent.

In Hammond, LA you have two roundabouts and a raised curb controlling US 51 Business south of I-12 and that area between the two roundabouts is with two major truck stops. So to patronize either Truck Stop, all traffic must use both roundabouts as the raised curbs eliminates left turns and creates RIRO for the business driveways thus forcing the semis to make 180 degree turns in a small diameter circle.

My question is, have state officials simply ignored the actual situation created by tight roundabouts for maneuverability to large vehicles?  Or is that they feel truckers, the back bone of US commerce, are not challenged enough already so making them pay attention more and screw the rest of traffic when they have to slow down to wait patiently for a semi circumventing the roundabout as the geometry of the circle slows down the time it takes to use it for truckers? After all they’re the same greedy politicians who allow overdevelopment in rural areas without expanding the highways around it allowing the roundabouts to be norm now.

To me math suggests that the truckers are at their limit using the roundabout supporting the trucker concerns of using them.  Plus the ones in Hammond, LA being placed not only for the interchange ramps, but to control movements to the truck stop patrons as well, is totally not taking in the situation that is at hand. That is with the truckers who have to use them and have to drive it with full scrutiny to avoid hopping the curbs etc. After all do most lawmakers really know what their constituents really experience?
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Re: Roundabouts and Semis
« Reply #1 on: April 22, 2022, 10:16:06 AM »

Or just, you know, make them big enough for trucks.
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JayhawkCO

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Re: Roundabouts and Semis
« Reply #2 on: April 22, 2022, 10:20:47 AM »

Or just, you know, make them big enough for trucks.

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Rothman

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Re: Roundabouts and Semis
« Reply #3 on: April 22, 2022, 10:29:58 AM »

NY requires aprons to accommodate precisely this situation.
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froggie

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Re: Roundabouts and Semis
« Reply #4 on: April 22, 2022, 10:30:34 AM »

In Hammond, LA you have two roundabouts and a raised curb controlling US 51 Business south of I-12 and that area between the two roundabouts is with two major truck stops. So to patronize either Truck Stop, all traffic must use both roundabouts as the raised curbs eliminates left turns and creates RIRO for the business driveways thus forcing the semis to make 180 degree turns in a small diameter circle.

I'm looking at GMSV from just this past January and not seeing the roundabouts you're referring to.


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roadman65

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Re: Roundabouts and Semis
« Reply #5 on: April 22, 2022, 10:32:23 AM »

In Hammond, LA you have two roundabouts and a raised curb controlling US 51 Business south of I-12 and that area between the two roundabouts is with two major truck stops. So to patronize either Truck Stop, all traffic must use both roundabouts as the raised curbs eliminates left turns and creates RIRO for the business driveways thus forcing the semis to make 180 degree turns in a small diameter circle.

I'm looking at GMSV from just this past January and not seeing the roundabouts you're referring to.




https://www.google.com/maps/dir/30.4820483,-90.4589004//@30.4769424,-90.4595573,16.76z/data=!4m2!4m1!3e0!5m1!1e1
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kphoger

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Re: Roundabouts and Semis
« Reply #6 on: April 22, 2022, 10:45:34 AM »

All three of those roundabouts have truck aprons.  The center islands are not bordered by hard curbs.  They also have extra pavement with yellow striping, which allows truckers extra space to navigate the roundabouts.

https://goo.gl/maps/YT86SHpVR2kKtnv98
« Last Edit: April 22, 2022, 10:48:38 AM by kphoger »
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froggie

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Re: Roundabouts and Semis
« Reply #7 on: April 22, 2022, 10:46:53 AM »

Okay...I had BUS 51 and mainline 51 switched in my brain.

But, in light of earlier comments, I'm still seeing truck aprons on those roundabouts.

Is it an inconvenience?  Perhaps.  But this setup should eliminate any problems there were with left turning traffic and crashes.  I'm guessing they had a lot of crashes pre-roundabout and determined this was a good solution to that.
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abefroman329

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Re: Roundabouts and Semis
« Reply #8 on: April 22, 2022, 11:56:51 AM »

All three of those roundabouts have truck aprons.  The center islands are not bordered by hard curbs.  They also have extra pavement with yellow striping, which allows truckers extra space to navigate the roundabouts.

https://goo.gl/maps/YT86SHpVR2kKtnv98
And, judging by the width of the tire tracks, it looks like people not driving trucks are taking advantage of the apron, too.
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thspfc

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Re: Roundabouts and Semis
« Reply #9 on: April 22, 2022, 12:20:38 PM »

Pros of roundabouts
Fewer crashes
Fewer emissions
Faster
No stopping/starting
Reduced congestion
Not complicated

Cons of roundabouts
God forbid truckers have to go slower for 100 feet
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CtrlAltDel

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SEWIGuy

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Re: Roundabouts and Semis
« Reply #11 on: April 22, 2022, 02:00:27 PM »

I think trucks can struggle with multi-lane roundabouts however.  I have seen a couple of minor accidents here in the Green Bay area where the truck struggled staying in the lane and touched a car in the lane next to them.
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kphoger

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Re: Roundabouts and Semis
« Reply #12 on: April 22, 2022, 02:02:55 PM »

I think trucks can struggle with multi-lane roundabouts however.  I have seen a couple of minor accidents here in the Green Bay area where the truck struggled staying in the lane and touched a car in the lane next to them.

I don't know a trucker could possibly stay in one lane through most roundabouts.  But that's the same as with 90-degree turns too.
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7/8

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Re: Roundabouts and Semis
« Reply #13 on: April 22, 2022, 02:09:15 PM »

I think trucks can struggle with multi-lane roundabouts however.  I have seen a couple of minor accidents here in the Green Bay area where the truck struggled staying in the lane and touched a car in the lane next to them.

In my area, they recommend that large trucks straddle both lanes entering and through the roundabout with their hazard lights on to prevent any cars from driving alongside in the roundabout.

This truck seems to be doing fine.

https://www.google.com/maps/@30.4755345,-90.4574139,3a,90y,120.32h,81.22t/data=!3m7!1e1!3m5!1sdzbHBrwXDd0R8epbv21gug!2e0!6shttps:%2F%2Fstreetviewpixels-pa.googleapis.com%2Fv1%2Fthumbnail%3Fpanoid%3DdzbHBrwXDd0R8epbv21gug%26cb_client%3Dmaps_sv.tactile.gps%26w%3D203%26h%3D100%26yaw%3D2.6700442%26pitch%3D0%26thumbfov%3D100!7i16384!8i8192

For sure, that truck apron (using Google's distance tool) is around 5.5-6m wide. In my region, we use only 3.0m and that still works okay.

Big John

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Re: Roundabouts and Semis
« Reply #14 on: April 22, 2022, 03:34:59 PM »

In Wisconsin, state law says trucks have priority over cars in a roundabout, so a car shouldn't have been travelling in the way of the truck.
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kphoger

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Re: Roundabouts and Semis
« Reply #15 on: April 22, 2022, 03:39:44 PM »

Wisconsin state laws don't apply in Louisiana.   :awesomeface:
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tradephoric

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Re: Roundabouts and Semis
« Reply #16 on: April 22, 2022, 08:25:32 PM »

Load shifts in roundabouts can lead to big issues:








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froggie

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Re: Roundabouts and Semis
« Reply #17 on: April 22, 2022, 10:54:27 PM »

Load shifts can lead to big issues in a lot of places, not just roundabouts.  And their load probably shifted because they were going too fast...that's simply physics.  Unless you have proof that they weren't going too fast in your photo examples.
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skluth

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Re: Roundabouts and Semis
« Reply #18 on: April 23, 2022, 02:06:06 PM »

I wish states would consider building interchange roundabouts like this or even this.
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Re: Roundabouts and Semis
« Reply #19 on: April 23, 2022, 02:27:38 PM »

I wish states would consider building interchange roundabouts like this or even this.

There is this one in Fisher's, Indiana, but they are admittedly thin on the ground.
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zachary_amaryllis

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Re: Roundabouts and Semis
« Reply #20 on: April 23, 2022, 02:52:14 PM »

This one near me: https://goo.gl/maps/Gx8GrwNmaaZ3GUrYA

I feel like it's well designed, yet about twice a month there's a truck on it's side on the SB side, because he went in too hot. The slip lane for NB 287, can be easily taken at 55 (at least in my car). The SB leg (which actually turns compass east here) can be safely taken at 30-35. The lance are nice and wide to allow for trucks turning. Speed limit here is 40, 25 in the actual roundabout, going to 65 just to the north of here, and 45 just to highway south of here (compass east)

But yet still, trucks wreck here.

This used to be a simple 'T' intersection, with slip lanes for the right turns, and a traffic light that defaulted to green for SB 287.
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DJStephens

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Re: Roundabouts and Semis
« Reply #21 on: April 24, 2022, 10:23:06 AM »

I wish states would consider building interchange roundabouts like this or even this.

Those are "traffic circles" or in New England terminology, rotaries.   Very common during the build up of the Boston area expressway network in the fifties.   Some have outlived there usefulness and should have been replaced with full interchanges 45 years ago.  Reformatory Circle in Concord, MA as a leading example.   
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jeffandnicole

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Re: Roundabouts and Semis
« Reply #22 on: April 24, 2022, 10:37:40 AM »

In Wisconsin, state law says trucks have priority over cars in a roundabout, so a car shouldn't have been travelling in the way of the truck.

However, this wouldn't be a widely known state law to most motorists. It does fall under common sense rules though...give a truck a little more space when turning.

NY requires aprons to accommodate precisely this situation.

Nearly all roundabouts in every state has aprons; they are standard features of a roundabout.
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Rothman

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Re: Roundabouts and Semis
« Reply #23 on: April 24, 2022, 10:44:25 AM »

I wish states would consider building interchange roundabouts like this or even this.

Those are "traffic circles" or in New England terminology, rotaries.   Very common during the build up of the Boston area expressway network in the fifties.   Some have outlived there usefulness and should have been replaced with full interchanges 45 years ago.  Reformatory Circle in Concord, MA as a leading example.
Rotaries and traffic circles are not the same, as rotaries follow the traffic rules of roundabouts.
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Scott5114

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Re: Roundabouts and Semis
« Reply #24 on: April 24, 2022, 11:50:54 PM »

NY requires aprons to accommodate precisely this situation.


What store sells aprons big enough to go around a truck?
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