What are the traffic rules governing this intersection?

[Absolute]

I almost got t-boned at a four way intersection this afternoon.

Three ways of the intersection are two-way streets. The fourth way is a one-way street, with traffic on the one-way street entering the intersection.


one-way
two-way two-way
two-way


I was on the two-way street facing the one-way street, so there were large "Do Not Enter" signs in front of me. Since I could not go straight, I had to make either a left or right turn. When the light changed, I saw a green left arrow, and a green right arrow. There was no non-directional green light. I have always taken green arrows to mean "You have the right of way in the indicated direction", so I started to make a left turn - and almost got T-boned by a car coming from the one-way street.

I investigated, and the guy on the one-way street had a green light. Obviously, he had the right of way, since a green light is a green light - but why did my street have the two green arrows?

[TheLoadedDog]

I investigated, and the guy on the one-way street had a green light. Obviously, he had the right of way, since a green light is a green light - but why did my street have the two green arrows?

By investigation, do you mean you asked him and he bullshitted you? Either he did bullshit you, or you need to get down to City Hall (or whoever does these things) and tell them their traffic lights are broken.

A green light is a green light, but a green arrow is a green light too. You can't have a green arrow opposing a green light. If that's happening, it's incredibly dangerous, and they need to either cycle the lights differently so the green arrows have a red opposite, or they need to ditch the arrows and replace them with a regular green light (then at least, you will know you might have to give way). If I were in that situation, I too would have taken the green arrows to mean I had absolute right of way.

[Gbro]

A green arrow is to protect you from other traffic. On this link page 56 is the green arrow,
http://www.dps.state.mn.us/dvs/DLTraining/DLManual/PDF/07ClassD/07%20ClassD%20Chapter5.pdf

If you think the signal didn't do that you should report it.

I report safety concerns to the DOT through e-mail. Its a good record for you and i have always received prompt responses.

[Absolute]

By investigation, do you mean you asked him and he bullshitted you? Either he did bullshit you, or you need to get down to City Hall (or whoever does these things) and tell them their traffic lights are broken.

I pulled over, got out of my car, and watched what the lights did from the sidewalk. This isn't the first time I've wondered what the hell is going on at this intersection, but it is the first time I've come so close to an accident.

Thanks for the input, I will report it.

[ZenBeam]

Are you originally from Massachusetts? IIRC (and this is from 20 years ago), they have oddities like this. Here in Michigan, a green arrow means you have the right of way. There? Not so much.

ETA: From here (11 b) (http://www.town.arlington.ma.us/Public_Documents/ArlingtonMA_TrafficRules/article7)
When a green arrow is exhibited together with a red or yellow lens, operators may enter the intersection to make the movement permitted by the arrow, but shall yield the right of way to vehicles and pedestrians proceeding from another direction on a green indication.

[SharkB8]

There are no traffic rules in Boston.

[Wheeljack]

Agreed. My understanding has always been that a green light permits you to move through the intersection if approaching traffic is clear, but a green arrow specifies that all cross traffic has a red.

[DesertDog]

When a green arrow is exhibited together with a red or yellow lens, operators may enter the intersection to make the movement permitted by the arrow, but shall yield the right of way to vehicles and pedestrians proceeding from another direction on a green indication.What the hell do they mean by "with a red or yellow lens"?

I go through an intersection similar to the one in the OP, but the two-way facing the one-way gets a green ball light, not arrows. They rely on your spotting the big, red Do Not Enter signs opposite to keep you from going straight.

[Rysto]

When a green arrow is exhibited together with a red or yellow lens, operators may enter the intersection to make the movement permitted by the arrow, but shall yield the right of way to vehicles and pedestrians proceeding from another direction on a green indication.
What the fuck? That's the most retarded traffic law I've heard in my life. Are rights on red not allowed in Massachusetts?

[Quercus]

What the fuck? That's the most retarded traffic law I've heard in my life. Are rights on red not allowed in Massachusetts?Right on red is permitted, but I think this particular law is concerned with LEFT turn arrows.

[muttrox]

It's to cover the case of the OP. It means that you are allowed to turn left, but that that you must yield to oncoming traffic, which also has green.

[Mycroft H.]

Zen Beam's citation notwithstanding, it is a poorly set up intersection and the road authority should change it. They were trying to emphasize that you should not proceed straight into the one way road, but as you experienced, it allows people to be confused. It does need to change. Either the green light for the one way road and the two green arrows on your leg each need to have their own green while the other directions are red, or there needs to be a sign indicating that the left turn on a green arrow must yield to oncoming traffic. I don’t like this second option and could not find a standard sign for it.

It would be good to report it to the city (or county or state, depending on the road authority).

[Acsenray]

What the hell do they mean by "with a red or yellow lens"?

I think it's essentially a red or yellow light that has a green arrow in the middle. Two colors. I have a vague recollection of seeing lights like that.

[Joey P]

I think it's essentially a red or yellow light that has a green arrow in the middle. Two colors. I have a vague recollection of seeing lights like that.
I think I understand the spirit of what the rule is trying to say, but it seems really odd. When I see a green arrow and another color light, I usually take that to mean that the arrow is for people making that turn and the light (without an arrow) is directed at people that are travelling stright through the intersection.

[ZenBeam]

It would be good to report it to the city (or county or state, depending on the road authority).Report what? A properly signaled (according to Mass. law) intersection that people from other states who don't know Mass. law are confused by?

I'm not saying this way of doing things is a good idea, but it's the traffic law of the entire state that would need to be changed.

[KidScruffy]

I investigated, and the guy on the one-way street had a green light. Obviously, he had the right of way, since a green light is a green light - but why did my street have the two green arrows?
Near my house is an intersection almost identical to that one. The difference is that the traffic would have been stopped when you had a green turn arrow, but you would have run the risk of hitting pedestrians who have a green walk sign. And this is in California, which doesn't have the law mentioned above. Seems pretty ridiculous to me, but what do I know...

[BrandonR]

Report what? A properly signaled (according to Mass. law) intersection that people from other states who don't know Mass. law are confused by?

Or they could just change the light setup at that particular intersection. It sounds like a dangerous situation and one that poses a genuine concern for visiting motorists.

[TheLoadedDog]

As a slight hijack - how much of a headache is it generally for out-of-state drivers in the US? If a Californian wanted to drive across the country to NYC, would it be:
a) A major headache involving lots of research
b) Very minor, and play it by ear as you go?

Is there a push for universal traffic law?

[Ignatz]

What is the intersection, MITer? I assume it is in Massachusetts, if you are at MIT.

That signal dislay is in violation of FEDERAL law and you should complain to the traffic agency in charge of the intersection. Mass. has been doing things their own way for decades, in flagrant violation of the Federal Highway Administration's "Manual on Uniform Traffic Control Devices" to which ALL road agencies are "required" to conform, at least theoretically. I say theoretically as there is an exception that allows states' rights to dictate, to the detriment of traffic safety and the poor interstate tourist/traveler. Does Mass. still have the red over yellow pedestrian signal indications?

The entire document can be read at http://mutcd.fhwa.dot.gov . The next edition is being formulated and anyone is able to submit comments through the federal register process.

Rather than link to the 1,000-page document, here are the specific pertinent sections and the overview of the Manual


“Section 4D.05 Application of Steady Signal Indications
Standard:
When a traffic control signal is being operated in a steady (stop-and-go) mode, at least one lens in each signal face shall be illuminated at any given time.
A signal face(s) that controls a particular vehicular movement during any interval of a cycle shall control that same movement during all intervals of the cycle.
Steady signal indications shall be applied as follows:
F. A steady GREEN ARROW signal indication:
1. Shall be displayed only to allow vehicular movements, in the direction indicated, that are not in conflict with other vehicles moving on a green or yellow signal indication or with pedestrians crossing in conformance with a WALKING PERSON (symbolizing WALK) or flashing UPRAISED HAND (symbolizing DONT WALK) signal indication (see Section 4D.09).
2. Shall be displayed on a signal face that controls a left-turn movement when said movement is not in conflict with other vehicles moving on a green or yellow signal indication or with pedestrians crossing in conformance with a WALKING PERSON (symbolizing WALK) or flashing UPRAISED HAND (symbolizing DONT WALK) signal indication (see Section 4D.09).
3. Shall not be required on the stem of T-intersections or for turns from one-way streets.”

"Overview [of the MUTCD]
The traffic control devices (TCD) are very critical for the safe and efficient transportation of people and goods. The Manual on Uniform Traffic Control Devices (MUTCD), by setting minimum standards and providing guidance, ensures uniformity of traffic control devices across the nation. The use of uniform TCDs (messages, location, size, shapes, and colors) helps reduce crashes and congestion, and improves the efficiency of the surface transportation system. Uniformity also helps reduce the cost of TCDs through standardization. The information contained in the MUTCD is the result of either years of practical experience, research, and or the MUTCD experimentation process. This effort ensures that TCDs are visible, recognizable, understandable, and necessary. The MUTCD is a dynamic document that changes with time to address contemporary safety and operational issues.
Key Messages:
B. The MUTCD contains the national standards governing all traffic control devices. All public agencies across the nation rely on the MUTCD to bring uniformity to the roadway. The MUTCD plays a critical role in improving safety and mobility of all road users.
C. The MUTCD is the law governing all traffic control devices. Non-compliance of the MUTCD ultimately can result in loss of federal-aid funds as well as significant increase in tort liability.
D. Uniformity of traffic control devices is critical in highway safety and mobility as well as cutting capital and maintenance costs of TCDs for public agencies and manufacturers.
E. The FHWA has established a sound process to incorporate new devices and applications in the MUTCD. The process involves the Federal Register rulemaking activity which encourages public involvement. Any interested person or organization may provide input to the rulemaking activity by submitting comments to the docket.
F. The process encourages innovation and flexibility while maintaining uniformity.
G. The success of the MUTCD depends on nationwide complete acceptance and application of the MUTCD as well as extensive participation by the practitioners in developing and evaluating the content of the MUTCD.
H. Input from practitioners and all other stakeholders is very critical in keeping the MUTCD current and relevant."

[Balthisar]

That signal dislay is in violation of FEDERAL law and you should complain to the traffic agency in charge of the intersection. Mass. has been doing things their own way for decades, in flagrant violation of the Federal Highway Administration's "Manual on Uniform Traffic Control Devices" to which ALL road agencies are "required" to conform, at least theoretically. I say theoretically as there is an exception that allows states' rights to dictate, to the detriment of traffic safety and the poor interstate tourist/traveler.
Just out of curiosity, can you provide a cite (federal code) that specifies that states must adopt the uniform rules, and that federal code provides exceptions due to states' rights? I'm not looking to pick a fight, but I always hear this "federal law" argument, and while it's good to have uniform rules, I've never been convinced that there's an actual requirement.

[jasonh300]

As a slight hijack - how much of a headache is it generally for out-of-state drivers in the US? If a Californian wanted to drive across the country to NYC, would it be:
a) A major headache involving lots of research
b) Very minor, and play it by ear as you go?

Is there a push for universal traffic law?

I've driven in 34 states and have never encountered anything like this. The only differing traffic law I've ever found from state to state is the right-turn-on-red law which a few states don't allow at all.

[jasonh300]

Just out of curiosity, can you provide a cite (federal code) that specifies that states must adopt the uniform rules, and that federal code provides exceptions due to states' rights?

No exact cite but this is what I read.

This is from the mutcd.fhwa.dot.gov site:


The 2003 Manual on Uniform Traffic Control Devices (MUTCD) Edition was published on November 20, 2003. The adopted changes were effective on December 22, 2003. 23 CFR provides the States with a 2-year period from the effective date to adopt the MUTCD. Therefore, by December 22, 2005 States were required to have adopted the National Manual or have a State MUTCD/supplement that is in substantial conformance with the National Manual. The role of our FHWA Division Offices is to review and approve any State MUTCD or supplement that is in substantial conformance with the National MUTCD. (23CFR 655.603(b). This list includes Puerto Rico and Washington D.C. as States.

They list D.C. and Indiana as the only two "states" that are not in compliance.

Massachusetts is listed as having adopted the national MUTCD and having a state supplement which is in "substantial conformance with the National Manual".

23 CFR refers to Title 23 of the Code of Federal Regulations http://www.access.gpo.gov/cgi-bin/cfrassemble.cgi?title=200423 which I don't have time to read, but you might find your answer in there.

[Ignatz]

Sorry, Balthisar, I left the board to get some sleep.

Absolute, try to contact MassHighway and get/buy a current copy of the Mass. version of the Manual. I have one from the 1960s from when I lived up there. The state later dropped centralized overview of the traffic device standards and left it up to the 351 cities and towns to "do their own thing" so I saw yellow YIELD signs entering 128 (now I-95) in Peabody as recently as 1993.

SOme states, including NC, have state legislation backing up the requirement for ALL traffic control devices, even those on private property open to the public and in gated communities to conform to the Manual.

Thanks, jasonh300 for the cite. Here are more of the US Code's details:


23 Code of Federal Regulations 655
The MUTCD is adopted by reference in accordance with title 23, United States Code, Section 109(d) and Title 23, Code of Federal Regulations, Part 655.603, and is approved as the national standard for designing, applying, and planning traffic control devices. View the Electronic Code of Federal Regulations Title 23: Highways, Part 655.603.

e-CFR Data is current as of March 19, 2008




Title 23: Highways
PART 655—TRAFFIC OPERATIONS


Browse Previous | Browse Next


Subpart F—Traffic Control Devices on Federal-Aid and Other Streets and Highways
Source: 48 FR 46776, Oct. 14, 1983, unless otherwise noted.


§ 655.601 Purpose.
To prescribe the policies and procedures of the Federal Highway Administration (FHWA) to obtain basic uniformity of traffic control devices on all streets and highways in accordance with the following references that are approved by the FHWA for application on Federal-aid projects:

(a) Manual on Uniform Traffic Control Devices for Streets and Highways (MUTCD), 2003 Edition, including Revision No. 1, FHWA, dated November 2004, and revision No. 2, FHWA, dated January 2008. This publication is incorporated by reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51 and is on file at the National Archives and Record Administration (NARA). For information on the availability of this material at NARA call (202) 741–6030, or go to http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html. It is available for inspection at the Federal Highway Administration, 1200 New Jersey Ave., SE., Washington, DC 20590, as provided in 49 CFR part 7. The text is also available from the FHWA Office of Transportation Operations' Web site at http://mutcd.fhwa.dot.gov .

(b) Guide to Metric Conversion, AASHTO, 1993. This publication is incorporated by reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51 and is on file at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202–741–6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html. This document is available for inspection as provided in 49 CFR part 7. It may be purchased from the American Association of State Highway and Transportation Officials, Suite 249, 444 North Capitol Street, NW., Washington, DC 20001.

(c) Traffic Engineering Metric Conversion Factors, 1993—Addendum to the Guide to Metric Conversion, AASHTO, October 1993. This publication is incorporated by reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51 and is on file at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202–741–6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html. This document is available for inspection as provided in 49 CFR part 7. It may be purchased from the American Association of State Highway and Transportation Officials, Suite 249, 444 North Capitol Street, NW., Washington, DC 20001.

[51 FR 16834, May 7, 1986, as amended at 60 FR 18521, Apr. 11, 1995; 61 FR 29626, June 11, 1996; 62 FR 1373, Jan. 9, 1997; 63 FR 8351, Feb. 19, 1998; 63 FR 33549, June 19, 1998; 64 FR 33753, June 24, 1999; 65 FR 13, Jan. 3, 2000; 65 FR 78958, Dec. 18, 2000; 67 FR 7076, Feb. 15, 2002; 69 FR 18803, Apr. 9, 2004; 69 FR 69819, Dec. 1, 2004; 71 FR 75115, Dec. 14, 2006; 72 FR 72582, Dec. 21, 2007]



§ 655.602 Definitions.
The terms used herein are defined in accordance with definitions and usages contained in the MUTCD and 23 U.S.C. 101(a).



§ 655.603 Standards.
(a) National MUTCD. The MUTCD approved by the Federal Highway Administrator is the national standard for all traffic control devices installed on any street, highway, or bicycle trail open to public travel in accordance with 23 U.S.C. 109(d) and 402(a). For the purpose of MUTCD applicability, open to public travel includes toll roads and roads within shopping centers, parking lot areas, airports, sports arenas, and other similar business and/or recreation facilities that are privately owned but where the public is allowed to travel without access restrictions. Military bases and other gated properties where access is restricted and private highway-rail grade crossings are not included in this definition.

(b) State or other Federal MUTCD. (1) Where State or other Federal agency MUTCDs or supplements are required, they shall be in substantial conformance with the National MUTCD. Substantial conformance means that the State MUTCD or supplement shall conform as a minimum to the standard statements included in the National MUTCD. The FHWA Division Administrators and Associate Administrator for the Federal Lands Highway Program may grant exceptions in cases where a State MUTCD or supplement cannot conform to standard statements in the National MUTCD because of the requirements of a specific State law that was in effect prior to the effective date of this final rule, provided that the Division Administrator or Associate Administrator determines based on information available and documentation received from the State that the non-conformance does not create a safety concern. The guidance statements contained in the National MUTCD shall also be in the State Manual or supplement unless the reason for not including it is satisfactorily explained based on engineering judgment, specific conflicting State law, or a documented engineering study. The FHWA Division Administrators shall approve the State MUTCDs and supplements that are in substantial conformance with the National MUTCD. The FHWA Associate Administrator of the Federal Lands Highway Program shall approve other Federal land management agencies MUTCDs and supplements that are in substantial conformance with the National MUTCD. The FHWA Division Administrators and the FHWA Associate Administrators for the Federal Lands Highway Program have the flexibility to determine on a case-by-case basis the degree of variation allowed.

(2) States and other Federal agencies are encouraged to adopt the National MUTCD in its entirety as their official Manual on Uniform Traffic Control Devices.

(3) States and other Federal agencies shall adopt changes issued by the FHWA to the National MUTCD within two years from the effective date of the final rule. For those States that automatically adopt the MUTCD immediately upon the effective date of the latest edition or revision of the MUTCD, the FHWA Division Administrators have the flexibility to allow these States to install certain devices from existing inventory or previously approved construction plans that comply with the previous MUTCD during the two-year adoption period.

[Tom Tildrum]

Offhand, it sounds like a flashing yellow left arrow could be the proper signal for this situation.

[jasonh300]

Offhand, it sounds like a flashing yellow left arrow could be the proper signal for this situation.

Once again, I'm too lazy to go back and look, but if you follow the links I posted last night, you'll find that flashing lights are not allowed in the U.S. when the light is in cycle. In other words, if a light is out of cycle, you'll get flashing red in one direction (meaning stop) and flashing yellow (meaning caution) in the other direction in a regular 4 way intersection without protected turns.

If a light cycles (goes Green, Yellow, Red and then the other light turns Green, etc.), one light has to be illuminated at all times.

The way it *should* work is when the green arrow is lit, the turn is protected and the oncoming traffic should have a red light. A "circular" green would indicate that the left turn is not protected and you have to yield to oncoming traffic, but it would create confusion since the circular green usually indicates you can go straight through and in this case, you'd be heading the wrong way onto a one-way street.

The only deviation from any of this I've ever seen in my extensive traveling-by-car was in Ontario (which isn't U.S. and falls under a different, although similar set of rules) where the green lights flash at the beginning of a cycle indicating a protected left turn...which confused the hell out of me the first time I saw it.

[Balthisar]

I guess I don't see that the states are required per se. In fact, it specifically mentions that they're encouraged, at least for non-highway funds roads. Of course, it's a moot point, because there's not any reason to adopt different standards. However in the case of the intersection mentioned -- unless it's federally funded (even partially), it seems like the state would have the right to put in a more intuitive traffic control device, wouldn't it?

Simplest solution seems to just put up a normal green light. Do Not Enter signs would seem to overrule the ability to go straight onto the one-way road despite the green light, and of course, if you have a green light you know that you have to yield to oncoming traffic before making the left. On the other hand, if it's night and there's an out of area driver that doesn't notice the Do Not Enter signs. I guess that could be a problem. But of course there advanced warning signs that say "Right Lane MUST turn Right," right? And is the left turn lane a normal traffic lane, or is it clearly marked as a left turn lane? Do you have the Google Maps link to this particular intersection?

jasonh300, most of the newer intersection lights I've seen do have the green arrow in Ontario. They use that flashing green when they've not installed arrows yet. Pretty slick, economical idea, I think. They call it "advanced green" rather than "protected left" I seem to think. Invariably, in my experience flashing green and green arrows always come in the cycle before the oncoming traffic. So once you lose the advanced green or the arrow, you can still turn left if the way is clear. Here in Michigan, most of the intersections with arrows give you the arrow only after the straight traffic in the cycle, and it's usually solid red during the straight traffic portion of the cycle. Lots of wasted opportunities there.

[jasonh300]

jasonh300, most of the newer intersection lights I've seen do have the green arrow in Ontario. They use that flashing green when they've not installed arrows yet. Pretty slick, economical idea, I think. They call it "advanced green" rather than "protected left" I seem to think.

The flashing green just seemed very foreign to me the first time I saw it. Even on more recent trips, I always pause a few seconds when I see it because I have to think about what it means.

BTW, advanced green means that the left turners get to go before the oncoming traffic. Lagging (retarded?) green is when the oncoming traffic goes first and then the turn lane gets the arrow at the end of the cycle. I think it also depends on whether the forward moving traffic moves with the left turners at the same time or if the opposing left turners go at the same time. There's different terms for each way. (I actually read quite a bit of the MUTCD the other night.)

In Louisiana, we have a mix of advanced and lagging greens, depending on the intersection. We have a lot of vehicle activated lights here and the sequence can change from cycle to cycle depending on traffic flow. One thing we do not seem to have here since Katrina is synchronized lights. You catch a red light at almost every corner no matter what speed you're going.

[GorillaMan]

As a slight hijack - how much of a headache is it generally for out-of-state drivers in the US? If a Californian wanted to drive across the country to NYC, would it be:
a) A major headache involving lots of research
b) Very minor, and play it by ear as you go?
Perusing this thread, I can't help but think the same thing. Apart from wondering how hard it must be to create a single system, what's with all the flashing stages? The only one you'll find in Britain is a brief intermediate pedestrian right-of-way stage at a basic crossing. Why do American junctions (sorry, intersections) need to use such awkward and clearly confusing systems?

[j666]

There are no traffic rules in Boston.
That is completely untrue, and only recent immigrants will spew this vile tripe.

Rule 1: The biggest car has the right of way
Rule 2: The ugliest car has the right of way
Rule 3: I have the right of way
Rule 4: The order in which the rules apply is at the discretion of the drivers

[Sane people do not drive in Boston.]

[jasonh300]

Why do American junctions (sorry, intersections) need to use such awkward and clearly confusing systems?

They don't. The nationwide U.S. system (with a few odd exceptions that are probably in error/poor engineering) for controlled intersections is:
a Red light means Stop
a Green light means Go
an Amber (Yellow) light means caution - the light is about to turn Red.
a Green arrow to the left means you can turn left without worrying about oncoming traffic (remember, we drive on the right side)
a Red or Green arrow to the right, sometimes used to keep right turning vehicles from running over pedestrians, usually accompanied by Walk/Don't Walk signals for the peds.

Uncontrolled intersections will have either a two-way or four way stop, indicated by octagonal STOP signs
OR
A flashing red light for the traffic that has to stop and a flashing amber light for traffic that does not have to stop, but indicating Caution-that there is an intersection there (very rare in urban areas, but seen more often in suburban or rural areas where a stop sign might not be visible enough)

The flashing lights scenario also happens (rarely) when the computer or control box for an intersection with traffic lights fails. The lights will start flashing and one direction, e.g. North/South will get a flashing Red and the other direction, e.g. East/West will get a flashing Yellow. I think this is a failsafe to keep something catastrophic from happening, such as all of the lights in the intersection turning green at one time.

This pretty much covers it...when there are exceptions, they're usually covered by a large sign at the intersection or mounted on the pole that holds the traffic signals detailing the exception (No Right Turn on Red, Turning Vehicles Yield to Pedestrians, Left Turn Yield on Green, etc.)

With this knowledge, you could safely drive anywhere in the United States and Puerto Rico...also Canada and probably many other countries.

[Ignatz]

Once again, I'm too lazy to go back and look, but if you follow the links I posted last night, you'll find that flashing lights are not allowed in the U.S. when the light is in cycle. In other words, if a light is out of cycle, you'll get flashing red in one direction (meaning stop) and flashing yellow (meaning caution) in the other direction in a regular 4 way intersection without protected turns.

If a light cycles (goes Green, Yellow, Red and then the other light turns Green, etc.), one light has to be illuminated at all times.

The way it *should* work is when the green arrow is lit, the turn is protected and the oncoming traffic should have a red light. A "circular" green would indicate that the left turn is not protected and you have to yield to oncoming traffic, but it would create confusion since the circular green usually indicates you can go straight through and in this case, you'd be heading the wrong way onto a one-way street.

The only deviation from any of this I've ever seen in my extensive traveling-by-car was in Ontario (which isn't U.S. and falls under a different, although similar set of rules) where the green lights flash at the beginning of a cycle indicating a protected left turn...which confused the hell out of me the first time I saw it.

Au contraire on the ban on flashing yellow during a cycle.

I'm not sure of the approval process used but I have seen several recently flashing yellow displays installed in left turn bays to allow drivers to turn left in gaps of oncoming traffic that has the circular green. They were converted from circular green phases that alternated with green arrow phases. The first one in the area was installed on a US numbered urban highway after a driver was killed when s/he failed to yield on the circular green that was displayed after the fully-protected leading green arrow phase for that lane was terminated.

[Mycroft H.]

I’ve recently seen the flashing yellow arrow for a protected turn across oncoming traffic as well. I just went through the intersection this past weekend. Evidently this is fairly new, well, allowed by a memo from just over 2 years ago. Some details can be found here (http://mutcd.fhwa.dot.gov/resources/interim_approval/ia_10_flashyellarrow.htm).

In trying to find something in the MUTCD (Minnesota version) on the flashing yellow arrow, I noted something that seems to apply to the OP. It can be found in this section (http://www.dot.state.mn.us/trafficeng/otepubl/mutcd/mnmutcd2008/mn%20mutcd-4%202008.pdf) (288 kB pdf) under section 4D.9 on page 4D-7. The section is titled “Unexpected Conflicts During Green or Yellow Intervals” and has the statement

“A steady GREEN ARROW or YELLOW ARROW signal indication shall not be displayed to vehicular movements that are in conflict with the following:
A. Other vehicles moving on a green or yellow signal indication…”

My reading of this is that the signal described in the OP does not meet this condition and, although apparently allowed by the contradicting Massachusetts laws, does lead to confusion and a potentially dangerous situation. This is the situation I meant to be reported in my comment post #12 that ZenBeam wondered about in post #15. (Although, granted, I did not know of the specific MUTCD statement against conflicts when I made the first post.)

Anyway, Absolute, if you want some ammunition to complain with, there's your citation. MUTCD Section 4D.9.

[Ignatz]

Absolute: What intersection is it? I'd like to check it out.

[Absolute]

Here is the offending intersection.

http://maps.google.com/maps?f=q&hl=en&geocode=&q=charles+st+and+1st+st,+cambridge,+ma&sll=42.367224,-71.077756&sspn=0.001292,0.00246&ie=UTF8&z=16&iwloc=addr

Google's Street View captured the light pattern - click the "Street View" button in the upper-right, and then use the curved arrow buttons in the upper-left to spin around. You can see the general green going one way, and the two green arrows going the other way. You have to zoom in a bit to see the green arrows.

[jasonh300]

Here is the offending intersection.

http://maps.google.com/maps?f=q&hl=en&geocode=&q=charles+st+and+1st+st,+cambridge,+ma&sll=42.367224,-71.077756&sspn=0.001292,0.00246&ie=UTF8&z=16&iwloc=addr

Google's Street View captured the light pattern - click the "Street View" button in the upper-right, and then use the curved arrow buttons in the upper-left to spin around. You can see the general green going one way, and the two green arrows going the other way. You have to zoom in a bit to see the green arrows.

Nice shot there. That's the first time I've seen any practical use for street view.

There really should be a sign hanging next to the light with the arrows....Turning Vehicles Yield to Oncoming Traffic.

That would make the intersection a little safer.

BTW, here's a link to the actual streetview:

Link (http://maps.google.com/maps?f=q&hl=en&geocode=&q=charles+st+and+1st+st,+cambridge,+ma&sll=42.367224,-71.077756&sspn=0.001292,0.00246&ie=UTF8&ll=42.367666,-71.077619&spn=0.000711,0.002704&t=h&z=19&layer=c&cbll=42.36721,-71.07774&cbp=2,293.39779288814975,,0,2.1212183368488136)

(I think I just found a bug in Google Maps. The streetview of the intersection is correct, but the pointer is off by about 1/2 block. I've noticed this a few times when playing with Streetview.)

[Ponder Stibbons]

Nice shot there. That's the first time I've seen any practical use for street view.

There really should be a sign hanging next to the light with the arrows....Turning Vehicles Yield to Oncoming Traffic.

That would make the intersection a little safer.

BTW, here's a link to the actual streetview:

Link (http://maps.google.com/maps?f=q&hl=en&geocode=&q=charles+st+and+1st+st,+cambridge,+ma&sll=42.367224,-71.077756&sspn=0.001292,0.00246&ie=UTF8&ll=42.367666,-71.077619&spn=0.000711,0.002704&t=h&z=19&layer=c&cbll=42.36721,-71.07774&cbp=2,293.39779288814975,,0,2.1212183368488136)

(I think I just found a bug in Google Maps. The streetview of the intersection is correct, but the pointer is off by about 1/2 block. I've noticed this a few times when playing with Streetview.)Wow, you're absolutely right. It's hard to believe but there's the photographic proof right there. A general green light in one direction, and two green turn arrows (with no "yellow lens" or any other lights whatsoever) in the other.

They definitely need to change SOMETHING. At the very least, a sign such as Jason suggests.

[Ignatz]

Thanks for the view. If that left/right arrow displays at the same time that the opposing direction shows a green ball, that definitely violates the federal standards and law. Mass. may have passed legislation that makes it legal to show an unprotected green turn arrow but that may be why Mass. has historically had a high crash rate. The intent of Mass. traffic engineers has been, ever since the green arrow was "invented" in the late '50s/early '60s, merely to use them to advise which way you could go or turn, and they apparently have never realized/adopted the federal requirement that they be used only for protected, i.e., exclusive, movements. I used to commute via the Revere Beach Parkway, then under the Metropolitan District Commission, and they rebuilt it in 1960 using green arrows on all of the signals, with arrows showing left, up, and right, all at the same time, for both directions. I haven't driven on that road for 30 years but I imagine that they are still that way. North Shore commuters please advise. I've lived in the south for many years but I can still tell a Mass. driver here because they try to turn left across my path when we both have green balls (I know, "band name!"). Green balls = circular green signals.

Absolute, try contacting the City of Cambridge traffic department signal folks and discuss it with them. The website, with phone numbers, is

http://www.cambridgema.gov/traffic/TrafficSignals.cfm

If you are at MIT, check with the traffic gurus about the matter, or, better yet, do a term paper or a thesis on the matter.

It was interesting to see that a Best Buy has replaced the old former Lechmere Sales store where I spent many hours and dollars. They pioneered the put your order in from the on- floor display and pick it up at the back of the store, and calling the salespeople "associates". I bought my first post-Trash 80 desktop computer there, a Packard Bell. Still got it and it would still work if I ever turned it on.

[Ignatz]

Also, Absolute, you should check with the Volpe Center around the corner at 88 Broadway, to get the straight skinny. That was the first federal transportation research center and is named after John A.Volpe, the alumnus of Boston's Wentworth Institute of Technology and former Mass. public works commissioner and Governor who became the first federal highway administrator under the father of our interstate highway system, President Dwight Eisenhower. I know, TMI.

From their web site:

The Volpe National Transportation Systems Center
Welcome to the Volpe Center's web site. The Center is part of DOT's Research and Innovative Technology Administration and is an innovative, federal, fee-for service organization. Our mission is to improve the Nation's transportation system. Our work is performed primarily for DOT, as well as other federal agencies and state, local, and international entities.

Since October 15, 2007, the site has been sporting a new look, showing the Volpe Center as an integral element of DOT's Research and Innovative Technology Administration (RITA). Keep an eye out for more changes as we continue to improve content and add functionality. We are interested in your comments and how we can best serve you.


John A. Volpe National Transportation Systems Center
55 Broadway
Cambridge, MA 02142

For comments or questions, contact:
Lynn Murray
617-494-2224
lynn.c.murray@volpe.dot.gov

[ZenBeam]

Absolute, in Ignatz's link to the City of Cambridge traffic department, there's a link to an online traffic signal complaint form. You know what you have to do... (I am so tempted to fill it in myself).

[Absolute]

Absolute, in Ignatz's link to the City of Cambridge traffic department, there's a link to an online traffic signal complaint form. You know what you have to do... (I am so tempted to fill it in myself).
Yep, that's what I did...I will let you know how they respond.

[Ignatz]

I was suspecting that the answer would be based on the wording found in the Town of Arlington traffic code cited in post #5 by ZenBeam, to the effect that traffic turning on ANY green signal (including and arrow) must yield to other traffic, but according to the Mass. Drivers Manual at

http://www.mass.gov/rmv/dmanual/index.htm

On page 80 it says:

Green Arrow
A green arrow means you may make a “protected” turn in the direction of the
arrow. As long as a green arrow displays for your turning lane, pedestrians and
oncoming vehicles should be stopped for red lights. Look closely for signs saying
you may turn only on a green arrow.

Good luck and please keep us posted. Be careful out there.