Left Turn on Red at DDIs

[UCFKnights]

My thought is this: if you want to allow turns on red, don't use a red right arrow at all - use one of those signal heads with a red ball and yellow/green arrows.

Or better yet, there is an actual dedicated signal indication for this: the flashing red arrow. Its universally understood, requires no signage at all, and if it were universally implemented, it could allow for more control of all intersections without needing things like blankout signs. Solid red arrow means no turn on red, flashing red arrow means turn after stop. It could even allow the intersections to switch between the 2, so if a pedestrian is detected, it can go solid for a minute, then back to flashing

[mrsman]

My thought is this: if you want to allow turns on red, don't use a red right arrow at all - use one of those signal heads with a red ball and yellow/green arrows.

That's how it's done in Utah. Most commonly you'll see this at the bottom of right-turn ramps at SPUIs (example). There aren't a lot of red right arrows in the state anyway, and most of them seem to exist to clarify an existing NTOR restriction that would be there anyway (example). Utah law does not allow right on a red arrow, but I can't think of a single place I've seen a red right arrow in the state without accompanying NTOR signage.

Florida does allow right on a red arrow unless signed otherwise and it drives me nuts. There are a bunch of intersections without arrows with signs banning turns on red, but there are also a ton of red right arrows that you can turn on after you stop (with no signage clarifying that this is allowed). I far prefer the Utah method.

I also prefer the Utah method, but maybe that's because I learned to drive in CA where red arrow means no turn on red.

I think the lack of nationwide uniformity on this issue has led to confusion.  While the MUTCD and UVC (and a majority of jurisdictions) take the approach that a solid red arrow is no turn on red, there are enough other states that will allow the turn to proceed after a complete stop.  Because of this, you will see a lot of unnecessary signs that are put up to clarify the position.

So it is a good practice for UT to put up the NTOR signs with the red arrow, even though this is technically unnecessary.  And it will only be practically unnecessary if every state adopted the same rules regarding red arrows.

In certain contexts, there is too much going on to even place the NTOR sign.  In some of the busiest intersections, you will see separate signal heads for straight traffic, turning traffic, and perhaps separate signal heads for buses and bikes.  Should each signal head get its own sign?  Isn't it quite confusing?  Would it be less confusing if the red arrow simply meant wait until a green arrow to make this turn?

In my view, and i know others have voiced it as well, it would seem quite easy to allow for flexibility.  For every intersection where there is a red arrow and the state allows you to proceed before green arrow, simply have the red arrow flash.  Now we can define a universal meaning to each signal:

Red orb = Wait to proceed.  RTOR after stop.  LTOR after stop one-way to one-way.
Red orb + NTOR sign. = Wait to proceed or turn.
Flashing red orb = Proceeding or turning on red permitted after stop.

Red arrow = Wait to turn.
Flashing red arrow = Turn on red permitted after stop.

[mrsman]

Allowing right on a red arrow never made sense to me even when Virginia did allow it. The red arrow seems to me to indicate "you're not allowed to move in this direction," whichever direction the arrow is pointing. It would be particularly useful if you had an intersection in which a right-turn-only lane gets a green at a different time from the other lanes moving in the same direction. 18th & L in DC is an example of that (in this June 2014 Street View, you can see the station wagon is illegally turning right on a red arrow–traffic going straight has a green, traffic turning right has a red arrow, and a sign says right turns must wait for the green arrow).

This is a growing application of red right arrow, separate phases for turning and peds/bikes.

A sign may be helpful, but the verbiage is not.  It is far simpler to say "No turn on red arrow."  Instructions are  better when they are direct.

[Amtrakprod]

My thought is this: if you want to allow turns on red, don't use a red right arrow at all - use one of those signal heads with a red ball and yellow/green arrows.

That's how it's done in Utah. Most commonly you'll see this at the bottom of right-turn ramps at SPUIs (example). There aren't a lot of red right arrows in the state anyway, and most of them seem to exist to clarify an existing NTOR restriction that would be there anyway (example). Utah law does not allow right on a red arrow, but I can't think of a single place I've seen a red right arrow in the state without accompanying NTOR signage.

Florida does allow right on a red arrow unless signed otherwise and it drives me nuts. There are a bunch of intersections without arrows with signs banning turns on red, but there are also a ton of red right arrows that you can turn on after you stop (with no signage clarifying that this is allowed). I far prefer the Utah method.

I also prefer the Utah method, but maybe that's because I learned to drive in CA where red arrow means no turn on red.

I think the lack of nationwide uniformity on this issue has led to confusion.  While the MUTCD and UVC (and a majority of jurisdictions) take the approach that a solid red arrow is no turn on red, there are enough other states that will allow the turn to proceed after a complete stop.  Because of this, you will see a lot of unnecessary signs that are put up to clarify the position.

So it is a good practice for UT to put up the NTOR signs with the red arrow, even though this is technically unnecessary.  And it will only be practically unnecessary if every state adopted the same rules regarding red arrows.

In certain contexts, there is too much going on to even place the NTOR sign.  In some of the busiest intersections, you will see separate signal heads for straight traffic, turning traffic, and perhaps separate signal heads for buses and bikes.  Should each signal head get its own sign?  Isn't it quite confusing?  Would it be less confusing if the red arrow simply meant wait until a green arrow to make this turn?

In my view, and i know others have voiced it as well, it would seem quite easy to allow for flexibility.  For every intersection where there is a red arrow and the state allows you to proceed before green arrow, simply have the red arrow flash.  Now we can define a universal meaning to each signal:

Red orb = Wait to proceed.  RTOR after stop.  LTOR after stop one-way to one-way.
Red orb + NTOR sign. = Wait to proceed or turn.
Flashing red orb = Proceeding or turning on red permitted after stop.

Red arrow = Wait to turn.
Flashing red arrow = Turn on red permitted after stop.

Exactly, like this signal is so complex, and the blank out sign makes it worse.


iPhone

[mrsman]

^^^^^

That is a great example of what not to do.  Where is this intersection?

Another problem is that there does not seem to be enough signal faces here.  One separate signal face for left turns, right turns, buses, and bikes, but no duplicate signal face.

[jakeroot]

^^^^^

That is a great example of what not to do.  Where is this intersection?

Another problem is that there does not seem to be enough signal faces here.  One separate signal face for left turns, right turns, buses, and bikes, but no duplicate signal face.

This is in Bellevue, WA. Southbound 108th at Main St.

There is a duplicate left turn signal on the far left corner, per Bellevue's policy, but no redundancy for the other signals.

The old intersection used to have a small bike lane to the left of the right turn lane (see here), along with a small median between the turn lanes, that allowed cyclists to travel straight-through, which cars were/are not allowed to do. But they eliminated the median, and placed the bike lane to the right of the travel lanes. I'm guessing this was done to allow southbound buses without creating havoc for cyclists. But it did result in a very complicated signal array.

[kphoger]

DDIs aren't one way streets....There can be arguments made on both sides of the issue, but on the strict interpretation of the statute, they are probably often illegal turns.

I'm not sure I agree with that.

Around here, Washington State signs them as two one-way streets. The ramps are also signed:

https://goo.gl/maps/85YQ4c1ed4r49qFS7

From what I understand, if a wide-enough median is present, that creates a divided highway. Thus, Michigan Left corridors should legally be divided highways, made up of two separate roadways, one traveling in one direction, and the other in the opposing direction. Here in WA, the median would have to be thirty feet or greater in width. I don't know what the rule is in Michigan, but I have to assume it's a similar number.

I agree with you about Michigan lefts:  assuming the median is wide enough, they count as two separate intersections.

Michigan state law permits LTOR "into a 1-way roadway".  (Note that is the case even when turning from a two-way street.)

MICHIGAN VEHICLE CODE – Act 300 of 1949

Section 257.612

(1) When traffic is controlled by traffic control signals, ... Red arrow and yellow arrow indications have the same meaning as the corresponding circular indications, except that they apply only to vehicle operators intending to make the movement indicated by the arrow. The following colors shall be used, and the terms and lights shall indicate and apply to vehicle operators as follows:

(c) If the signal exhibits a steady red indication, the following apply:

(ii) Vehicular traffic facing a steady red signal, after stopping before entering the crosswalk on the near side of the intersection or at a limit line when marked or, if there is no crosswalk or limit line, before entering the intersection, may make a right turn from a 1-way or 2-way street into a 2-way street or into a 1-way street carrying traffic in the direction of the right turn or may make a left turn from a 1-way or 2-way street into a 1-way roadway carrying traffic in the direction of the left turn, unless prohibited by sign, signal, marking, light, or other traffic control device. The vehicular traffic shall yield the right of way to pedestrians and bicyclists lawfully within an adjacent crosswalk and to other traffic lawfully using the intersection.

Michigan state law defines the term "roadway" as the entire portion of a highway intended for vehicular traffic.  Notably, the definition also states that more than one "roadway" can comprise a single "highway".

MICHIGAN VEHICLE CODE – Act 300 of 1949

Section 257.55

"Roadway" means that portion of a highway improved, designed, or ordinarily used for vehicular travel. In the event a highway includes 2 or more separate roadways, the term "roadway", as used herein, shall refer to any such roadway separately, but not to all such roadways collectively.

So the question then remains:  how can we tell if a highway counts as one roadway or two separate roadways?  Michigan state law provides the answer to this question in the definition of "intersection".

MICHIGAN VEHICLE CODE – Act 300 of 1949

Section 257.22

"Intersection" means:

(a) The area embraced within the prolongation or connection of the lateral curb lines, or, if none, then the lateral boundary lines of the roadways of 2 highways which join one another at, or approximately at, right angles, or the area within which vehicles traveling upon different highways joining at any other angle may come in conflict.

(b) Where a highway includes 2 roadways 30 feet or more apart, then every crossing of each roadway of such divided highway by an intersecting highway shall be regarded as a separate intersection. In the event such intersecting highway also includes 2 roadways 30 feet or more apart, then every crossing of 2 roadways of such highways shall be regarded as a separate intersection.

There's your answer.  If there is more than 30 feet between center lines, then one should treat it as two separate intersections.  If there is less than 30 feet between center lines, then one should treat it as a single intersection.

With that in mind, I don't understand how you make the leap to assume that a DDI counts as two separate roadways.  The distance between sides of a DDI isn't generally more than 30 feet, is it?  Assuming it's less than 30 feet, then each end of a DDI should be treated as a single intersection–ONE WAY signs or not.

[ran4sh]

The distance between sides of a DDI isn't generally more than 30 feet, is it?

A lot of them are, especially at the points where the on and off ramps meet the roadways of the crossroad. The roadways generally have a little more curvature than necessary, to reduce the possibility that a driver simply drives straight onto the bridge/underpass into oncoming traffic. The roadways often reduce to less than 30 feet separation when crossing the bridge/underpass, but that's not what matters.

[jakeroot]

With that in mind, I don't understand how you make the leap to assume that a DDI counts as two separate roadways.  The distance between sides of a DDI isn't generally more than 30 feet, is it?  Assuming it's less than 30 feet, then each end of a DDI should be treated as a single intersection–ONE WAY signs or not.

I don't understand how you can build a DDI without one-way signs. Every state requires keeping right of the center of the roadway. If the opposite-side driving portion of a DDI were not separate roadways, what legal reason would I have to stay left?

Obviously, the signs and markings are what makes you stay left, but I think those signs and markings also create separate one-way roadways.

[Dirt Roads]

With that in mind, I don't understand how you make the leap to assume that a DDI counts as two separate roadways.  The distance between sides of a DDI isn't generally more than 30 feet, is it?  Assuming it's less than 30 feet, then each end of a DDI should be treated as a single intersection–ONE WAY signs or not.

I don't understand how you can build a DDI without one-way signs. Every state requires keeping right of the center of the roadway. If the opposite-side driving portion of a DDI were not separate roadways, what legal reason would I have to stay left?

Obviously, the signs and markings are what makes you stay left, but I think those signs and markings also create separate one-way roadways.

You guys are digging at the root of this thread.  It seems to me that the primary purpose of a DDI is to change the traffic patterns such that all of the left turn patterns avoid conflicting movements.  Unless there is some safety rationale (such as poor visibility), restricting a left turn on red in the DDI seems counterintuitive to the overarching goal of pushing as many cars through the left turn movements to get as close as theoretically possible. 

Can't remember if I mentioned this, but the specific DDI location at I-85 and NC-119 in Mebane originally had temporary stop signs at the end of each ramp (left turns) when it was first constructed, with only the crossover moves on NC-119 being protected by traffic signals.  After the remainder of the signal heads were installed, I kept making left turns on red until I realized that it was still illegal in North Carolina.  But the entire interchange certainly worked better with the stop signs.  Therefore, it seems to me that the rollout of DDIs this is an impetus for North Carolina to consider eliminating its "no left turn on red" laws.  When necessary, "No Left Turn on Red" (R13-B) or "No Turn on Red" (R10-11) should be employed (regardless of the laws).

[jakeroot]

Can't remember if I mentioned this, but the specific DDI location at I-85 and NC-119 in Mebane originally had temporary stop signs at the end of each ramp (left turns) when it was first constructed, with only the crossover moves on NC-119 being protected by traffic signals.  After the remainder of the signal heads were installed, I kept making left turns on red until I realized that it was still illegal in North Carolina.  But the entire interchange certainly worked better with the stop signs.  Therefore, it seems to me that the rollout of DDIs this is an impetus for North Carolina to consider eliminating its "no left turn on red" laws.  When necessary, "No Left Turn on Red" (R13-B) or "No Turn on Red" (R10-11) should be employed (regardless of the laws).

Despite the law, would it be acceptable to install "Left on Red OK After Stop" for the off-ramp left turns?

I would think a basic policy for DDIs might be: if the movement is single-lane, yield or stop signs would be fine. More than one lane, flashing red arrows? If the crosswalk was along the outer edge, I could see prohibiting left on red, although only for the off-ramp left turns (off-ramp right turns are like any other right turn, no need to install NTOR signs even with double turns IMO).

There is a DDI outside of of Durban, South Africa that is signalized only at the crossovers. The off-ramp turns onto the wrong-way sections are both double right yields (they drive on the left). Seems to work decently well. Although it's pretty uncommon, there are definitely quite a few double right turns in the US with yield signs (example here in Phoenix); I don't see why the opposite (double left yield) couldn't also work. Video of the interchange I'm referring to in action...

https://youtu.be/b8jO0b4wXfk

[1995hoo]

^^^^

I suspect–this is only a guess–is that a double right yield is deemed more acceptable in the USA because the driver is closer to oncoming traffic and thus presumably has less to see around than he would at a double left yield.

[jakeroot]

^^^^

I suspect–this is only a guess–is that a double right yield is deemed more acceptable in the USA because the driver is closer to oncoming traffic and thus presumably has less to see around than he would at a double left yield.

The only time you see double left yields in the US is largely at traffic lights across oncoming traffic, and even then, it's pretty rare (apart from some places). Curb to curb left turn "slip lanes" are pretty much just at DDIs and the very rare one in a downtown core (one I know of in Vancouver, BC, left on red being OK here but there is a signal).

It wouldn't surprise me if agencies are treating the off-ramp left turns at DDIs the way they would treat any other left turn, even though they are fairly unique in being curb to curb left turns that arguably don't need as much protection.

[US 89]

Doesn't a double right yield technically happen in every multilane roundabout? Plenty of those in the US.

[jakeroot]

Doesn't a double right yield technically happen in every multilane roundabout? Plenty of those in the US.

Yes, very true. Although, admittedly, the crash rate at multi-lane roundabouts isn't much to write home about

[mrsman]

Can't remember if I mentioned this, but the specific DDI location at I-85 and NC-119 in Mebane originally had temporary stop signs at the end of each ramp (left turns) when it was first constructed, with only the crossover moves on NC-119 being protected by traffic signals.  After the remainder of the signal heads were installed, I kept making left turns on red until I realized that it was still illegal in North Carolina.  But the entire interchange certainly worked better with the stop signs.  Therefore, it seems to me that the rollout of DDIs this is an impetus for North Carolina to consider eliminating its "no left turn on red" laws.  When necessary, "No Left Turn on Red" (R13-B) or "No Turn on Red" (R10-11) should be employed (regardless of the laws).

Despite the law, would it be acceptable to install "Left on Red OK After Stop" for the off-ramp left turns?

I would think a basic policy for DDIs might be: if the movement is single-lane, yield or stop signs would be fine. More than one lane, flashing red arrows? If the crosswalk was along the outer edge, I could see prohibiting left on red, although only for the off-ramp left turns (off-ramp right turns are like any other right turn, no need to install NTOR signs even with double turns IMO).

There is a DDI outside of of Durban, South Africa that is signalized only at the crossovers. The off-ramp turns onto the wrong-way sections are both double right yields (they drive on the left). Seems to work decently well. Although it's pretty uncommon, there are definitely quite a few double right turns in the US with yield signs (example here in Phoenix); I don't see why the opposite (double left yield) couldn't also work. Video of the interchange I'm referring to in action...

If one were really thinking very hard about it, the right turn on red move is one where a vehicle is likely only going to encroach on one direction of traffic (and likely only the closest lane of traffic).  As such, unless there are difficult geometries or too many pedestrians, the movement is generally considered safe, since you proceed only against one direction of traffic, not two.

The same line of thinking would also apply to the left on red situation from one way to one way.  Your car is basically making the same type  of movement as the RTOR, just in reverse.  It is true, that due to drivers sitting on the left side, it may be harder to see around the corner, but in all other respects the LTOR is only encroaching on one direction of traffic.

The LTOR from two-way to one-way is also somewhat similar, but with a twist.  In a simple signalized intersection (without separate arrow phases), when two-way sees red, both directions see red.  The LTOR movement will only encroach on one direction of traffic (the one-way side street green) and is thus a legal movement in WA,OR,ID, MI.  But the reason why this is so, is because the red light stops oncoming traffic. But given that many intersections theses days have complicated signalization, I fear that there is no good way for a driver to distinguish between a red light meaning that cross-traffic has a green vs. a red light meaning that opposing traffic has a green.  There are just too many variables, so I can definitely agree with the majority of states that prohibit this movement on red, even though you are only encroaching on one direction of traffic.

[Another distinction is that RTOR on LTOR one-way to one-way are movments that will hug the corner and by definition not cross the center line of the intersection.  The two-way to one-way left turn will cross the center of the intersection, so the driver is more exposed.]

Which brings us to the DDI.  It probably would not be considered two separate intersections, because the medians are typically too narrow, but the movement of the left turn from offramp to street only encroaches on one direction of traffic.  If one is OK with the LTOR one-way to one-way movement, then this movement is inherently not different.  It is a movement that only encroaches on one direction of traffic, with the proviso that it is a left movement instead of a right movement.  Now obviously, without writing specific laws dealing with the situation, a driver is likely confused about whether it is legal.  But it is not inherently more usnafe than typical LTOR one-way to one-way.  So, the movement should be allowed.  And signage about the legality of these movements should be clarified, with a "left turn may turn on red after stop" or a "no turn on red" when geometry of the intersectoin makes the movement dangerous.

Before DDIs were a thing, I am quite familiar with another intersection where drivers drove on the wrong side of the street.  I present the intersection of East Way and Center Way (lower level) in Los Angeles, in the middle of LAX:

https://www.google.com/maps/@33.9444131,-118.4017903,3a,75y,94.31h,76.71t/data=!3m7!1e1!3m5!1sGH0CBFvfFOo9YJQnBEVG4Q!2e0!6shttps:%2F%2Fstreetviewpixels-pa.googleapis.com%2Fv1%2Fthumbnail%3Fpanoid%3DGH0CBFvfFOo9YJQnBEVG4Q%26cb_client%3Dmaps_sv.tactile.gps%26w%3D203%26h%3D100%26yaw%3D328.04297%26pitch%3D0%26thumbfov%3D100!7i13312!8i6656

Now East Way (and West Way) are both two-way streets that drive on the reverese side.  This is because the main LAX loop (World Way)is a big counter-clockwise loop around the terminals.  East Way and West Way are designed to provide a shortcut, and the easiest way of providing the shorcut without having both directions of East Way interfere with each other at the World Way intersections is by making East Way a wrong-way street.  Center Way is a dual one-way in the direction of exiting the airport.  Most of its traffic is from those who have exited the parking lots, not the general loop trafffic.

Now if you are driving on Center Way and you see this intersection, there is no good reason why a left on red shouldn't be allowed here.  Yes, the LAX traffic volumes are heavy, but the movement of a left turn on red simply hugs the corner and only encroaches on one direction of traffic.  There is no sign.  Is a LTOR legal?  The movment from East Way to Center Way doesn't allow turn on red, but there is a sign to clarify that.

[Dirt Roads]

Which brings us to the DDI.  It probably would not be considered two separate intersections, because the medians are typically too narrow, but the movement of the left turn from offramp to street only encroaches on one direction of traffic.  If one is OK with the LTOR one-way to one-way movement, then this movement is inherently not different.  It is a movement that only encroaches on one direction of traffic, with the proviso that it is a left movement instead of a right movement.  Now obviously, without writing specific laws dealing with the situation, a driver is likely confused about whether it is legal.  But it is not inherently more usnafe than typical LTOR one-way to one-way.  So, the movement should be allowed.  And signage about the legality of these movements should be clarified, with a "left turn may turn on red after stop" or a "no turn on red" when geometry of the intersectoin makes the movement dangerous.

Agreed, except that I can see some situations where heavy left turn traffic from one or both of the off-ramps could block the stacking of traffic for cars having a green phase signal into the crossover section of the DDI (which could cause gridlock).  In that case, you would need two left turn lanes and probably need "No Left Turn on Red" signage.

[mrsman]

Which brings us to the DDI.  It probably would not be considered two separate intersections, because the medians are typically too narrow, but the movement of the left turn from offramp to street only encroaches on one direction of traffic.  If one is OK with the LTOR one-way to one-way movement, then this movement is inherently not different.  It is a movement that only encroaches on one direction of traffic, with the proviso that it is a left movement instead of a right movement.  Now obviously, without writing specific laws dealing with the situation, a driver is likely confused about whether it is legal.  But it is not inherently more usnafe than typical LTOR one-way to one-way.  So, the movement should be allowed.  And signage about the legality of these movements should be clarified, with a "left turn may turn on red after stop" or a "no turn on red" when geometry of the intersectoin makes the movement dangerous.

Agreed, except that I can see some situations where heavy left turn traffic from one or both of the off-ramps could block the stacking of traffic for cars having a green phase signal into the crossover section of the DDI (which could cause gridlock).  In that case, you would need two left turn lanes and probably need "No Left Turn on Red" signage.

Sure.  Heavy ramp movements at the interchange probably led to the construction of a DDI in the first place.  If the traffic is heavy enough, and sightlines difficult, a no turn on red could be justified.