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Author Topic: Rant: Why aren't Michigan lefts the standard on new arterial streets?  (Read 3703 times)

kernals12

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Left turns are the bane of traffic engineers, ruining the otherwise perfect signal precession that could guarantee drivers green lights.

But in the 60s, Michigan solved that problem by incorporating u turns into the medians of divided highways to allow for left turn movements while prohibiting them from the main intersection


Studies have shown they result in enormous improvements in safety and traffic flow. Because they also require the use of a wide median, they offer space for landscaping and stormwater drainage.

Imagine if this had become the standard design for new arterial streets all over the country, and perhaps the world. Think of all the time, money, and lives saved.

Why the f*ck aren't these everywhere?
« Last Edit: July 16, 2021, 07:50:47 PM by kernals12 »
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Max Rockatansky

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Not that I disagree but it is worth noting that there are other factors in play around Metro Detroit where a good chunk of Michigan Lefts are located.  Some of the traffic flow on arterials into Detroit has been impacted by the largely free flowing limited access capacity around them.  With the decline of the automotive industry there just isnít nearly as much traffic in general flowing into Detroit on arterials or limited access roadways. 

That said, Florida leaps off the page in my mind as a state where Michigan lefts could be a huge benefit given there is a huge reliance on timed signals.  One of the most frustrating things about driving around a surface highway in Florida  is waiting for a long left hand turn light to run its cycle.
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SkyPesos

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How about one of its variants, like the Superstreet/J-turn OH 4B uses?

Not on OH 4B, but here's one of the fancier superstreets in the state.
« Last Edit: July 16, 2021, 01:21:34 PM by SkyPesos »
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Even better, use jughandles like in NJ, where not only can you prohibit left turns, but all turning traffic keeps to the right, and faster traffic can pass on the left without anyone slowing down.
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The fact that they require a larger median is a negative, not a positive.
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Left turns are the bane of traffic engineers, ruining the otherwise perfect signal precession that could guarantee drivers green lights.

But in the 60s, Michigan solved that problem by incorporating u turns into the medians of divided highways to all for left turn movements while prohibiting them from the main intersection


Studies have shown they result in enormous improvements in safety and traffic flow. Because they also require the use of a wide median, they offer space for landscaping and stormwater drainage.

Imagine if this had become the standard design for new arterial streets all over the country, and perhaps the world. Think of all the time, money, and lives saved.

Why the f*ck aren't these everywhere?
Michigan Lefts are a pain ... trust me on this:  You don't want them everywhere.
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enormous improvements in safety and traffic flow

*In studies where flow is measured amongst thru traffic only.  These traffic studies often make the assumption that the majority of traffic at an intersection will proceed straight, rather than turning.  This is NOT a safe assumption to make at an impressive percentage of major intersections.

Another issue- Michigan lefts require a wide enough median to facilitate a left turn.  If trucks are involved, that requires an even wider space.  Even in the illustration above, the median appears to be about 36 feet wide.  That's a wide enough corridor to put in three traffic lanes!  Two 12-foot lanes in each direction, plus 36 feet in the median, and say, 20 feet on either side of the road, amounts to 104 feet of right-of-way.  You need a corridor at least 100 feet wide to make this happen.  Michigan planned their roads to be this way from the get-go; good luck retrofitting this scheme somewhere else.
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kernals12

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enormous improvements in safety and traffic flow

*In studies where flow is measured amongst thru traffic only.  These traffic studies often make the assumption that the majority of traffic at an intersection will proceed straight, rather than turning.  This is NOT a safe assumption to make at an impressive percentage of major intersections.

Another issue- Michigan lefts require a wide enough median to facilitate a left turn.  If trucks are involved, that requires an even wider space.  Even in the illustration above, the median appears to be about 36 feet wide.  That's a wide enough corridor to put in three traffic lanes!  Two 12-foot lanes in each direction, plus 36 feet in the median, and say, 20 feet on either side of the road, amounts to 104 feet of right-of-way.  You need a corridor at least 100 feet wide to make this happen. Michigan planned their roads to be this way from the get-go; good luck retrofitting this scheme somewhere else.

Notice how the title says new arterials.
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Max Rockatansky

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But itís still a factor.  It probably is a more difficult sell to plan an arterial road with a huge median versus one that follows a more conventional width.  That wide median means less room for development along the arterial highway.
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kernals12

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Left turns are the bane of traffic engineers, ruining the otherwise perfect signal precession that could guarantee drivers green lights.

But in the 60s, Michigan solved that problem by incorporating u turns into the medians of divided highways to all for left turn movements while prohibiting them from the main intersection


Studies have shown they result in enormous improvements in safety and traffic flow. Because they also require the use of a wide median, they offer space for landscaping and stormwater drainage.

Imagine if this had become the standard design for new arterial streets all over the country, and perhaps the world. Think of all the time, money, and lives saved.

Why the f*ck aren't these everywhere?
Michigan Lefts are a pain ... trust me on this:  You don't want them everywhere.
Try experiencing life without them.
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kernals12

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Re: Rant: Why aren't Michigan lefts the standard on new arterial streets?
« Reply #10 on: July 16, 2021, 07:56:56 PM »

But itís still a factor.  It probably is a more difficult sell to plan an arterial road with a huge median versus one that follows a more conventional width.  That wide median means less room for development along the arterial highway.

I didn't think about that. Who needs enormous improvements in throughput and safety? Won't someone think of the strip malls and car dealerships!
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kernals12

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Re: Rant: Why aren't Michigan lefts the standard on new arterial streets?
« Reply #11 on: July 16, 2021, 08:01:39 PM »

MA 9 through the Golden Triangle, a massive retail area, in Natick and Framingham, probably has just enough width to accommodate Michigan Lefts. Not to mention how much nicer it would be if the rusty metal guardrail made way a nicely landscaped median that could also serve to drain the enormous volume of stormwater runoff from the massive parking lots in the area that frequently floods the Speen Street underpass
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Max Rockatansky

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Re: Rant: Why aren't Michigan lefts the standard on new arterial streets?
« Reply #12 on: July 16, 2021, 08:04:39 PM »

But itís still a factor.  It probably is a more difficult sell to plan an arterial road with a huge median versus one that follows a more conventional width.  That wide median means less room for development along the arterial highway.

I didn't think about that. Who needs enormous improvements in throughput and safety? Won't someone think of the strip malls and car dealerships!

I mean, those properties do generate money and tax revenue.  Kind of a difficult sell to propose a road that will be more efficient in flowing traffic but attract less develop along side it. 

Another consideration worth noting is how willing the traveling public will be to accept more difficult access to businesses for the sake of better through traffic flow?  Example; on Grand River Avenue one often couldnít just turn left into a business and had to flip a U-turn at the next Michigan left.  That U-turn process isnít as often seamless as you think it is, especially it involves driving several blocks past where you want to go.  People in Metro Detroit might be used to that, but in places like Florida they would lose their minds about not being able to turn left into a business. 
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jakeroot

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Re: Rant: Why aren't Michigan lefts the standard on new arterial streets?
« Reply #13 on: July 16, 2021, 08:22:38 PM »

The Michigan Left's waterloo could be its main draw: throughput. Do new arterials really need the capacity offered by Michigan Lefts? Or is a five lane road with TWLTL sufficient?

On top of that, they can get so aggressively wide and take so much land, they simply aren't practical in some areas. Land is so expensive in the Seattle region that building a Michigan Left corridor is basically out of the question. Too much land. WSDOT has already spent 30 years buying land for a new freeway (WA-167), and you'd need to widen a road dramatically to make it a true Michigan Left corridor.

There's also the simple matter of there not being any new arterial streets. Most development in Seattle is infill. The only new roads are neighborhood streets and some arterial widening as necessary.

They are also miserable experiences for pedestrians. The lack of consistent four-way intersections creates long distances between "given" crossing points (those created by the simple intersection of two streets). Speaking of long distance walks: the crossings are very long too, and you often have to deal with double right turns that frequently have only a yield condition.

The only time I think they could be used is along corridors with either a busway in the centre or maybe a rail line down the median (either raised or at-grade).
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Re: Rant: Why aren't Michigan lefts the standard on new arterial streets?
« Reply #14 on: July 16, 2021, 08:35:55 PM »

They are also miserable experiences for pedestrians. The lack of consistent four-way intersections creates long distances between "given" crossing points (those created by the simple intersection of two streets). Speaking of long distance walks: the crossings are very long too, and you often have to deal with double right turns that frequently have only a yield condition.

Just cross one direction at a time when it's clear; it will periodically clear out due to the traffic signals. If you're walking along it, it doesn't have to be at an intersection.
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Max Rockatansky

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Re: Rant: Why aren't Michigan lefts the standard on new arterial streets?
« Reply #15 on: July 16, 2021, 08:41:03 PM »

They are also miserable experiences for pedestrians. The lack of consistent four-way intersections creates long distances between "given" crossing points (those created by the simple intersection of two streets). Speaking of long distance walks: the crossings are very long too, and you often have to deal with double right turns that frequently have only a yield condition.

Just cross one direction at a time when it's clear; it will periodically clear out due to the traffic signals. If you're walking along it, it doesn't have to be at an intersection.

Thatís what we used to do on Grand River given we would had to walk several blocks to the next pedestrian signal.  In a place like Seattle that lack of pedestrian friendliness would never fly.
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jakeroot

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Re: Rant: Why aren't Michigan lefts the standard on new arterial streets?
« Reply #16 on: July 16, 2021, 08:45:47 PM »

They are also miserable experiences for pedestrians. The lack of consistent four-way intersections creates long distances between "given" crossing points (those created by the simple intersection of two streets). Speaking of long distance walks: the crossings are very long too, and you often have to deal with double right turns that frequently have only a yield condition.

Just cross one direction at a time when it's clear; it will periodically clear out due to the traffic signals. If you're walking along it, it doesn't have to be at an intersection.

Thatís what we used to do on Grand River given we would had to walk several blocks to the next pedestrian signal.  In a place like Seattle that lack of pedestrian friendliness would never fly.

Let me just roll off this massive AASHTO-style curb...

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Max Rockatansky

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Re: Rant: Why aren't Michigan lefts the standard on new arterial streets?
« Reply #17 on: July 16, 2021, 08:50:16 PM »

They are also miserable experiences for pedestrians. The lack of consistent four-way intersections creates long distances between "given" crossing points (those created by the simple intersection of two streets). Speaking of long distance walks: the crossings are very long too, and you often have to deal with double right turns that frequently have only a yield condition.

Just cross one direction at a time when it's clear; it will periodically clear out due to the traffic signals. If you're walking along it, it doesn't have to be at an intersection.

Thatís what we used to do on Grand River given we would had to walk several blocks to the next pedestrian signal.  In a place like Seattle that lack of pedestrian friendliness would never fly.

Let me just roll off this massive AASHTO-style curb...



Heh, it was amusing to see my elderly Grand Father try to run across Grand River.  He wasnít exactly sure footed but as far as I know he never had a serious close calls with traffic.  My Mom certainly didnít like what he was doing but he insisted on not putting miles on the Chevette (later a Malibu). 
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Re: Rant: Why aren't Michigan lefts the standard on new arterial streets?
« Reply #18 on: July 16, 2021, 10:04:08 PM »

Left turns are the bane of traffic engineers, ruining the otherwise perfect signal precession that could guarantee drivers green lights.

But in the 60s, Michigan solved that problem by incorporating u turns into the medians of divided highways to all for left turn movements while prohibiting them from the main intersection


Studies have shown they result in enormous improvements in safety and traffic flow. Because they also require the use of a wide median, they offer space for landscaping and stormwater drainage.

Imagine if this had become the standard design for new arterial streets all over the country, and perhaps the world. Think of all the time, money, and lives saved.

Why the f*ck aren't these everywhere?
Michigan Lefts are a pain ... trust me on this:  You don't want them everywhere.
Try experiencing life without them.
Theyíre not exactly life support.  Try driving with them.  Theyíre a pain.  Trust me on that.
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Re: Rant: Why aren't Michigan lefts the standard on new arterial streets?
« Reply #20 on: July 16, 2021, 10:37:45 PM »

The disadvantages are they are usually about a quarter of a mile down the street so you have to go about a half mile out of your way in order to make a left turn and you have to stop up to three times to make one left turn.

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Re: Rant: Why aren't Michigan lefts the standard on new arterial streets?
« Reply #22 on: July 16, 2021, 11:41:51 PM »

Those are kind of similar to Michigan Lefts, but aren't really the same thing (I think they are called J-turns). Michigan Lefts usually allow right-on-red and then left-on-red for the U-turn, and no bulb-out is required to accommodate the U-turns.

Practically, they are very similar and you can achieve a lot of the same goals with them, but they technically operate a bit differently.

Michigan Lefts are a bit easier to modify too, since you can pretty easily add or delete lanes, U-turn points, and other bits as necessary. And the large bulb-out can be kind of ugly, just from a personal point of view.
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Re: Rant: Why aren't Michigan lefts the standard on new arterial streets?
« Reply #23 on: July 17, 2021, 12:03:44 AM »

Left turns are the bane of traffic engineers, ruining the otherwise perfect signal precession that could guarantee drivers green lights.

But in the 60s, Michigan solved that problem by incorporating u turns into the medians of divided highways to allow for left turn movements while prohibiting them from the main intersection


Studies have shown they result in enormous improvements in safety and traffic flow. Because they also require the use of a wide median, they offer space for landscaping and stormwater drainage.

Imagine if this had become the standard design for new arterial streets all over the country, and perhaps the world. Think of all the time, money, and lives saved.

Why the f*ck aren't these everywhere?

I agree that the Michigan Left or similar treatments such as the superstreet should be used everywhere it is possible. The superstreet design used in North Carolina, especially when the road is converted before the commercial development occurs, is what I think should happen on most arterials.
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Re: Rant: Why aren't Michigan lefts the standard on new arterial streets?
« Reply #24 on: July 17, 2021, 06:17:19 PM »

Around here, if you put in a screwy design like that people will just ignore it and turn left anyway. It happened for months on Telegraph Road (VA-241) in Alexandria when they built a new ramp on the right to replace an old left turn at a lightópeople still illegally turned leftóand people still make U-turns two lights down the road instead of using the ramp to South Kings Highway in the same area.

I suspect part of it is outdated sat-navs. If the device says to turn left, some people are flat-out determined to turn left, period.

Edited to add one other thing the OP will never accept: A lot of municipalities do not WANT to "guarantee drivers green lights." Plenty of places view that as anathema.
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