The left-turn-on-green-arrow-only debate
Posted on June 30th, 2008 – 6:05 AMBy Roadguy
Here’s my column from the Sunday paper. If you’ve already read it elsewhere, please skip on down to the comments below. Thanks.
Alert reader Jan from Brooklyn Center does a bit of fuming whenever her car waits at certain intersections:
Reading your articles and others on possible ways to save on gasoline, I have seen no comments on one of the traffic signal restrictions that is applied arbitrarily all over the city — that is the “left turn on green arrow only.”
While there are many places where this is a necessity because of heavy traffic and dangerous intersections, there also are many intersections where traffic is light and you can sit idling when there is no traffic from any direction.
Alert readers Gregg from Eden Prairie and Yvonne from Brooklyn Park wrote in to express similar unhappiness; Gregg even called for a law against red left-turn arrows.
While the arrows may seem arbitrary, they’re not, says Kevin Schwartz, an engineer for the Minnesota Department of Transportation’s metro district. Sight lines, speed limits, traffic volumes, the number of oncoming lanes and the number of turn lanes all play a role in determining which intersections get left-turn arrows.
The red/green arrow setup is vastly safer than what traffic folks call the “green ball” — a plain round green light — because the arrow removes the judgment call of when to zip across oncoming traffic, Schwartz says.
Schwartz said intersection designers tend to err on the side of safety, and while the arrows may be appropriate during rush hours, he knows they can be frustrating when traffic is light.
A remedy may be on the way, he said, in the form of a new kind of light: the flashing yellow arrow, which can be used during off-peak periods and allows left-turning drivers to proceed with caution.
Some states already have them, and one is being tested at Hwy. 110 and Dodd Road in Mendota Heights, Schwartz said. He’s hopeful that they’ll eventually be approved for wider use; Jan, Gregg and Yvonne are hoping so, too.
SCOOTING ALONG
Alert reader Gerry from Bloomington writes:
I’ve encountered many motor scooters on the local streets. These seem to be able to only go about 30 mph. Many times they were on roads with speed limits of 35 and 40 mph. Have they a right to be there even though they cannot go the speed limit?
Bloomington is very prepared to answer Gerry’s question: The city has put together an 11-page guide on what sorts of vehicles can go where. Mopeds and motorized bikes that can travel up to 30 mph aren’t allowed on freeways but are legal on city streets, even those with higher speed limits.
21 Responses to "The left-turn-on-green-arrow-only debate"
I was thinking this very thing sitting at a red light yesterday. We’re all so concerned over gas use that some people park on the highest part of the parking lot so they can roll out, but we have some simple things we can do to solve all sorts of traffic problems. Here are some other examples:
* Better use of timing lights so that cars can move continuously without having to stop for lights.
* Allowing right turns on red.
* At night, make major roads flash yellow on stop lights; turn side streets into flashing red, so they operate like stop signs.
* Do more to prohibit blocking/impeding on roadways, thereby reducing backups and traffic snarls.
One of my friends has vehemently complained about the hard left turn arrow at an intersection close to my home. I can’t say that I disagree with his logic, but I don’t mind the wait if the traffic requires it — the signal is set up on a meter, and it is pretty reactive.
I like the idea of the yellow flashing arrow. Previously, I thought it was the same as the “green ball with arrow” — after the green arrow expires, left turners are still allowed to proceed with caution (after yielding to on-coming traffic). But now that I understand that the yellow flashing arrow can be modified so that it acts like the green ball at off-peak times of the day and as a hard left signal at on-peak times, I’m more impressed. Something that combines safety with some flexibility — what a novel concept. Who do I need to start petitioning to get it approved in my neighborhood?
One thing I’ve noticed at two lights in my area that have the green ball WITHOUT the soft left arrow is that a fair number of left-turners are not yielding to oncoming right-turners. I don’t know if the yellow flashing arrow would fix that, but it couldn’t hurt.
I like the idea of the flashing yellow arrow at off peak times, it seems like a good compromise.
St Louis Park employs varied traffic light timing depending on time of day, during the rush hours the lights work on a timed cycle, but during off-peak hours and on weekends the lights work on sensors. The lights stay green for the main roads unless someone actually comes up to the intersection from a side street, then they get a green. Edina does the same thing druing the evening hours, it seems to keep things moving pretty well.
Sensors make a lot of sense as far as saving time and fuel while reducing pollution from idling vehicles.
I had a good laugh reading the question about scooters not being able to “go the speed limit.” It’s not a minimum! Apparently, Gerry has never driving through Amish country.
The night red/yellow flash is a great idea for saving gas, and used to be used more widely in this state. It’s still used at minor intersections in Wisconsin, but the mantra in this state, both on the part of engineers and drivers, has been to make the roads as idiot-proof as possible, which winds up causing higher delays. Stop lights that operate 24 hours a day, stop signs where yield signs would do, all-way stops, and drivers that freak out about yield signs and roundabouts.
Of course, with the roads set up to take the decisions away from drivers, it gets that much easier to not pay attention, talk on the phone, eat your lunch, apply your makeup, etc. This is pretty much the opposite of the east-coast driving mentality, where lanes are narrow, people drive fast, and you pay attention constantly because you have to. More efficient, but less “comfortable”.
I don’t see that mentality changing any time soon, even with gas at $4 and rising.
I’ve sat at plenty of LONG red arrows, so I can sympathize with Jan.
However, it’s even more frustrating when there NEEDS to be a left arrow and there’s not! For those of you ever visiting the U of M west bank, you’ll find that to make a left turn from heading north on 19th Ave (which eventually turns into the 10th Ave Bridge) to head west on Washington Ave in the Seven Corners area is nearly impossible. Given the increased amount of traffic due to the bridge collapse, there are lots of vehicles heading south and turning right (west) on Washington Ave. Without the arrow, these people technically have the right of way AND it’s only exacerbated by the stoplight in front of the Holiday Inn - traffic backs up so you can’t even turn left when the “green ball” turns yellow.
I’ve emailed the city of Minneapolis multiple times because it seems as if there’s the capability to have a green arrow, but all to no avail.
If some intersections go flashing red/yellow at night, it would have to be accompanied by a massive and pervasive education program. On the rare occasions when people are confronted with flashing lights now, they have absolutely no idea what to do about them. I have seen people blow through the flashing red, stop and wait for all the traffic to clear on a flashing yellow even though the other have a flashing red, and everything in between. Unless people are taught what to do in this situation, it’ll be a real mess out there. In stead of spending a few extra bucks on gas, we’ll be spending it on collision repairs, hospital bills and a few funerals. I prefer the safer rather than faster (which is what really irritates people) or more fuel efficient mode.
Part of the problem is that in this state, there’s no red/yellow flash anymore. So when they’re flashing, people tend to assume that it’s flashing red in all directions.
But even when it’s flashing red in all directions, yes, I see people do incredibly stupid things. Unfortunately it’s hard to do public education and reach everyone. Only way around it is to have people re-take a drivers test when they renew their license, which I think is exactly what should be done.
I find it humorous that Gerry had to ask if mopeds were legal or not. I’m not suprised that the question came from Bloomington. This is not an obscure topic - it’s in the Minnesota driving laws pamphlet they give you when you receive your license. You should know the basic laws of driving before you start driving.
Understand the need for turn arrows at busy intersections or during rush hour. However, there are WAY too many lights with arrows operating 24/7 at smaller intersections. VERY frustrating waiting at night or on the weekend when traffic’s light. Also, why the need for a yellow arrow? Wouldn’t a solid green for off hours w/arrow during busy hours do the same job?
I also agree I’d like to revert to flashing yellows at night at the smaller intersections. Drivers that can’t figure out what a flashing light means have no business having a license. (Rules for flashing lights are covered in the drivers manual). Again, very frustrating waiting for nobody.
Michigan has the green arrow at the end of the cycle, which allows the traffic passing through the intersection to move on first. Makes sense, as there is almost always several times more cars going straight than turning.
It works like this: When the light for the through traffic turns green, the left-turn red arrow flashes, meaning it becomes a stop sign: proceed with caution. Same premise as the flashing yellow they are testing here. If there are still cars waiting to turn left at the end of the green, the green arrow turns on.
As it is, if I find myself stuck at a red left-turn signal and no one is around, I just go.
Even most 50cc scooters can top out around 35-38mph when you de-restrict them. My 1963 Vespa is smaller than some 50cc scoots, but has a 150cc engine, allowing me to go around 55-58mph. Er, and the 70 miles per gallon is okay, too.
Here’s a tale of two streets in Cottage Grove: They are both 4 lane roads with a median, and marked as 35 mph zones. They both have an interchange with US 61, a 65 mph freeway, and both go through a few blocks worth of commercial area before residential subdivisions.
That being said, they are very different at their respective intersections with “East Point Douglas Rd” just two blocks east of US 61.
80th St has left turn arrows with the “green ball”
Jamaica,1 mile south, has the hard left turn arrows.
My question is, WHY!!!!! They’re the SAME road design carrying the SAME levels of traffic to the SAME freeway! They are even both set up to only allow cross traffic on East Point Douglas to take turns (separate stages for south-bound and north-bound) One has a Cub, the other a Rainbow. One has a Kohls, the other a Target. One has a Menards, the other (had) a Home Depot.
The point is, these traffic engineers really don’t have an over-riding formula, personal preference comes into play.
Given the topic, the following link might be of interest to some:
This is Chapter 2 of MnDOT’s Signal Design Manual, discussing signal phasing and operations. If you scroll down to page 2-4, it lists MnDOT’s criteria for determining if a “hard left arrow” (known in the engineering world as a “protected left”) is required, vice going with a “protected-permitted” signal (the 5-lens signal that has both the arrow and the green ball).
I’ll tell you what is used in many other parts of the country: When the delayed green times out, the green arrow simply turns off. There’s no prohibition to turning left.
In the wisdom of Minnesota, they make left turns ‘illegal’ by adding the ‘red left turn arrow’.
With the 35W/62 construction, it’s very frustrating at Nicollet and Diamond Lake Road. This now handles the traffic for 46th, 50th, and soon 60th. Why can’t we have delayed green on all four corners?
Froggie, maybe you can provide perspective: Are the criteria for left-turn arrows for locally controlled roads the same as for state-controlled roads? The reason I’m asking is where I live (Plymouth), almost every signaled intersection has a hard green arrow, even the smaller ones. Could it be possible each municipality has its own set of guidelines?
DGB: many other areas of the country also have a large number of protected-only turn signals (i.e. red left arrows). Maryland and Virginia are two states that come to mind. And I also saw plenty of them in both the Seattle and San Diego metro areas.
Ed: I’d have to do more digging to check. Theoretically, those county and local projects that use state aid funding would have standards similar to the state highways. But if it was purely local funding used, it’s quite possible that the local municipality used their own guidelines.
The guidelines are based on speed, number of turn lanes, lanes that they’re crossing, and the sight line to oncoming traffic.
The trouble is that the guidelines for using the “hard left” arrow are maybe a little too overzealous. On one hand, having the red arrow definitely increases safety, and really doesn’t cost anything extra to install. On the other hand, it does increase delay and therefore fuel as well.
What works well when it’s busy may seem like overkill in the middle of the night. Most of the intersections don’t even warrant signals in the middle of the night (hence my support of the red/yellow night flash). But, until the flashing yellow arrow, there wasn’t a well-understood way to switch between the “hard left” and the yield-on-green based on the time of day.
The flashing yellow arrow solves that problem, and based on testing it was well-understood by drivers, more so than the “left turn yeild on green”. I understand that Michigan will be removing the flashing red arrow in favor of the flashing yellow. The flashing red arrow required a complete stop before making the left turn, which wasn’t very efficient.
To Froggie & Joe G: The problem as I see it is common sense. Minnesota can establish all the specs under the sun. However it still boils down to what is sensible. The spec, unfortunately gives MnDot a place to hide.
It’s ironic that there are specs for left turn arrows, while at the same time a bridge falls down, killing 9? people.
Government at it’s best? or worst?
Well since you put it that way, you have to consider that the DOTs are often “required” to dumb down the roads, due to the level of (or lack of) common sense amongst drivers.
Many accidents, including fatal accidents, are the result of that lack of common sense amongst drivers…or a simple lack of awareness. You can’t legislate it…but transportation departments at all levels are often called upon or outright required to account for it, hence why a lot of them “err on the side of safety”, because they need to cover their tail.
It’s sad, and it’s not the way things should be done, but that’s what happens when you have stupid drivers, an overzealous government, and greedy lawyers…
Amen to that, Froggie.
