Roundabouts and Semis

[jakeroot]

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.

Are there really enough "Yield to entering traffic"  traffic circles remaining for that to be a noteworthy difference? Pretty much every circular intersection that I have seen in this country has entering traffic yielding to circulating traffic.

[hotdogPi]

Sometimes there's "is this a circle or not", such as these:

https://www.google.com/maps/@42.5925842,-70.9637526,15.8z

https://www.google.com/maps/@42.4552291,-71.0899526,18.55z

In both cases, the main road has priority.

[jamess]

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

Thats the intention.

Why on earth would you think that "make them pay attention" is a bad thing????

[english si]

Rotaries and traffic circles are not the same, as rotaries follow the traffic rules of roundabouts.

Though the Stanton St Quintin example (M4/A429/A350/B4122) has traffic lights controlling two corners, and so doesn't follow the traffic rules of roundabouts.

The Lutterworth (M1/A4303/A4304) example is very much a roundabout though.
<Removed post from other thread>

[kphoger]

There is precisely zero reason a freeway should not always have an Interstate shield. Change my mind.

There are good reasons why not to give freeways interstate shields, kphoger gave two, 'too short' is another. Tolls, possibly?

But yes, the onus should be more on the "not everything needs to be an interstate" crowd to explain why a freeway shouldn't be one than the "bring out the blue and red shields" to try and justify interstate status for a freeway that meets the basic criteria of being up to standards and forming a coherent addition to the network.

Wrong thread, |english si|.

[kphoger]

Are there really enough "Yield to entering traffic"  traffic circles remaining for that to be a noteworthy difference? Pretty much every circular intersection that I have seen in this country has entering traffic yielding to circulating traffic.

Depends what region you're in.

Southern Illinois has plenty of non-standard setups:

Stop signs in the middle, but only on two approaches
Town square, yield signs in the middle, but only on two approaches
Town square, no traffic control at all (I once saw I-57 traffic diverted through this;  it was... interesting.)

[english si]

Wrong thread, |english si|.

dealt with.

[jakeroot]

Are there really enough "Yield to entering traffic"  traffic circles remaining for that to be a noteworthy difference? Pretty much every circular intersection that I have seen in this country has entering traffic yielding to circulating traffic.

Depends what region you're in.

Southern Illinois has plenty of non-standard setups:

Stop signs in the middle, but only on two approaches
Town square, yield signs in the middle, but only on two approaches
Town square, no traffic control at all (I once saw I-57 traffic diverted through this;  it was... interesting.)

These sorts of setups are far and away a minority of circular intersections. Enough so I don't think they even could be called anything besides a town square or something.

[Ned Weasel]

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

The fact that about a third of the parking spaces in that Petro require blind-side backing (when you can't pull through from the other spaces) is a much greater concern than the roundabouts, with their generous geometry clearly showing they were engineered for trucks.

[kphoger]

Are there really enough "Yield to entering traffic"  traffic circles remaining for that to be a noteworthy difference? Pretty much every circular intersection that I have seen in this country has entering traffic yielding to circulating traffic.

Depends what region you're in.

Southern Illinois has plenty of non-standard setups:

Stop signs in the middle, but only on two approaches
Town square, yield signs in the middle, but only on two approaches
Town square, no traffic control at all (I once saw I-57 traffic diverted through this;  it was... interesting.)

These sorts of setups are far and away a minority of circular intersections. Enough so I don't think they even could be called anything besides a town square or something.

Except for the part where I said "Depends what region you're in".  I can't think of a single "modern" roundabout, with yield-on-entry at all approaches, anywhere in southern Illinois.

Well, except for (1) this six-way monstrosity in Zeigler, for which you'd have to ignore the angle parking and the island so big there's a park inside, and (2) the Saint Louis suburbs, such as this one in Belleville that used to be uncontrolled.

In other words, "these sorts of setups" are actually the majority of circular intersections in southern Illinois.

[bwana39]

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

This wide single lane design might be great. In Texas, they make the same basic roundabout, but they make it two lanes wide.
Those are confusing and they increase the sideswipe incursions.

The ones in Texas are generally not on roads with significant truck traffic.

[ran4sh]

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

The fact that about a third of the parking spaces in that Petro require blind-side backing (when you can't pull through from the other spaces) is a much greater concern than the roundabouts, with their generous geometry clearly showing they were engineered for trucks.

Seems normal for Petro and TA truck stops. A lot of drivers don't blind-side back anyway (they turn left while moving forward and then they back straight)