Michigan left | Hacker News Reader

Michigan left

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77 pointsIgorPartola77 comments

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I'll see your Michigan left and raise you a magic roundabout

http://en.wikipedia.org/wiki/Magic_Roundabout_(Swindon)

That just looks like insanity. To think, Americans are confused by simple one-lane roundabouts.

We might not be as confused by them if they were more common. I'd like to see more roundabouts.

However, I think the magic roundabout can wait until the next generation...

I drive through this twice a day:

http://maps.google.com/?ie=UTF8&ll=42.505215,-83.758199&...

It's a triple roundabout with a highway bridge separating two of them. The internals are arguably simpler but there are more entrances/exits than the magic roundabout.

For bonus points, check out what state this is in.

(I use Bing because last I checked Google still doesn't have a good satellite view of this, despite it being several years old now.)

I've been through that intersection! Let me tell you, coming off the highway expecting a normal intersection and getting dumped into that is pretty crazy. Not sure why they chose that design... Crazy MDOT.

If you sit down and try to draw the traffic light situation for that set of roads, this is actually a better solution than anything else I've been able to come up with. All the traffic-light situations I've mentally drawn out deadlock during rush hour with reasonable assumptions about people ending up in the middle of intersections accidentally as the light goes red, and have terrible throughput by comparison at all times of day. Presumably the actual civil engineers came to the same conclusion, only with better numbers and models. I can not imagine that was an easy sell, they must have had a rock-solid case.

They're only confusing because there aren't any rules! A significant part of learning to drive in Britain is learning how to use roundabouts. In the US, they're just a donut-shaped free-for-all.

This seems like as good a forum as any... what exactly are the rules for two-lane roundabouts? From which lane is it okay to exit? If you're in the inner lane and want to exit onto the left lane of a four-lane road, do you have to watch out for people in the outer lane, or do they have to watch out for you?

I won't talk about left and right because I'll get confused.

If you want to exit after 90 degrees, outer lane. If you want to exit after 180 degrees (straight through), either lane. If you want to exit after 270 degress, inner lane at first, then start indicating you are exiting, perhaps moving to outer lane before exit. The latter sounds confusing, in practice it isn't, mainly because other people will be expecting it.

It didn't even occur to me that left and right lanes get confusing. My apologies.

My confusion about the multi-lane roundabout mostly stems from the scenario where two cars, entering from streets 90* in the direction of the flow apart, both want to go straight through. If the one entering 'upstream' takes the inner lane and the one 'downstream' takes the outer lane, it would seem that in some timing conditions you'd get a collision situation when the inner lane car tries to exit but must cross the outer lane to do so. Is this a practical concern? Is there a universal set order of precedence for this case, e.g. inner lane always yields if necessary?

You have the additional rule that everything gives way to traffic already on the roundabout, which (in practice) means that particular timing event doesn't occur. The downstream car cannot enter the roundabout until the upstream car has gone past, or it can enter only if the upstream car is too far upstream and is not a threat. In either case, there is no collision.

In places I've driven where there might be confusion, they mark the lanes with arrows to show which ones are exiting and when.

They work pretty seamlessly in my experience. You only have to look one way (upstream), instead of two, to judge whether to enter the intersection, and you don't have the time-waste of traffic lights.

I agree, I drive both in the US and Ireland, and in Ireland once you know the rules of navigating a roundabout it's usually trivial to navigate all roundabouts. Just look at the 3 pics on this page: http://www.drivingschoolireland.com/roundabouts.html

In the US (at least in the Boston area) it's another matter, and it's almost as if people just don't know what they're doing, and after doing my driving test here I'd believe it. :)

I should add that in Ireland there are still people who can't navigate roundabouts/traffic circles/rotaries, but I think due to the less dense population it's a bit less of a problem (except for some motorways around Dublin).

Definitely; I'm from the UK and just took my California driving test - it's amazing how simple it is! Didn't even have to reverse around any corners. Although I've never had to do that outside of my British driving test, either...

New Jersey Jughandle: http://en.wikipedia.org/wiki/Jughandle

You have to make a left by basically taking almost like a freeway ramp off to the right.

If you miss your left turn ramp on the right in some parts of Jersey, you end up driving many miles to get another opportunity due to all the Jersey barriers that basically prevent real left-hand turns.

ARGH - I HATE those. Couple those with poor signage and out-of-towners will be lost for, well, if not hours, certainly tens of minutes. :/ (cherry hill ... lost several times in that area and no ways to turn around for miles).

It is a lot better than collisions at lights. A NJ DOT friend says the jughandles are a lot safer-- the principle is keeping stopped and turning cars away from moving traffic.

Would many DOT workers say their systems are stupid? Michigan DOT people probably justify the Michigan Left as safe/efficient/etc, and other places use roundabouts (Camden seems to have removed their roundabout(s) last time I was there).

Also, forcing people to drive an extra 3-4 miles because they missed a turn is probably not very good for the environment. Just sayin'

Traffic circles (roundabouts) are not the same thing as jughandles.

I believe mgkimsal was using roundabouts as another alternative to the two solutions already presented (Michigan lefts and jughandles).

> Also, forcing people to drive an extra 3-4 miles because they missed a turn is probably not very good for the environment. Just sayin'

Compared to damage of burning up a few cars every few months in accidents? Just sayin'

Missing a turn in New Jersey is a unique kind of frustration. The frustrating thing is that these are not highways, but simple routes that in most states would have normal intersections.

The system is clearly more efficient if you know exactly where you are going - it's an expert system. Which also implies it's unforgiving to people unfamiliar with it. (As in, me.)

Me too. Made me insane the first time I drove around NJ... until the understanding kicked in. Then I saw the efficiencies though that took awhile to make up for the earlier frustrations as a visitor.

The reverse Jughandle is the standard way to change Autobahns in Germany, driving many miles if you miss the intersection included. But hey: no speed limit!

I know where we have one of these in Michigan. It's awful. You need to make it, or you are in for quite a detour.

When I was in highschool in New Jersey in the 1970s, right-on-red was legalized; a classmate realized that this meant that under light traffic conditions, if he faced a red light while driving down the highway, he could turn off onto the jughandle, then make a right back onto the highway, regardless of whether the cross-traffic light was still green or had turned red.

More recently, Google maps at one point had a routing bug that caused it to propose a 360-degree double U-turn at every intersection while traveling along US 1, which in practice would result in the same maneuver.

The worst offenders are easily the towns that mix the jughandle turns with "traditional" left turn intersections; you never know which damn lane to be in to turn.

Looking at YOU Brick, NJ! >:/

I like how the Wikipedia article does not mention how this strategy turns the streets into soul sucking suburban wastelands. The Michigan left may reduce accidents, but it divides neighbourhoods (reference: anywhere on 8 Mile).

This is a very bad idea.

Can you explain why? Unless I'm misunderstanding, pedestrians can still cross, and the neighbourhoods are divided by the massive highway, rather than the specific turning pattern...?

In most of Michigan, the roads are enormous, development is sparse, and there are no sidewalks to speak of. It's tied in with the history of the state as a center of auto industry and the first attempts at car-centric planning.

Saying that the "Michigan Left" is the cause isn't exactly correct, but it does allude to the overall nature of the layout.

As a 28-year Michigander (Flint/Detroit area), I don't think the left turning mechanism is responsible for any neighborhood divides...you could say that the divided highway contributes to this, but I am more inclined to blame "White Flight" (http://en.wikipedia.org/wiki/White_flight).

I blame Michigan's anti-business labor and tax law.

I blame people who blame everything on "unions and taxes" regardless of how little or how much they know about an actual problem.

I'm tired of Detroiters blaming white flight for everything.

I brought up 8 mile as an example but Woodward is just as bad dividing the white people in Royal Oak from the white people in Berkeley.

You can't walk across the street with those huge boulevards. That's the point.

The divided boulevard divides neighborhoods, not the Michigan Left. Left Turn lanes would actually make it harder to cross 8 mile.

I'm not a fan of Michigan zoning whatsoever, but in this case, the damage is done with or without the Michigan Left.

That's a good point but it's chicken / egg. Now every new boulevard in Greater Detroit is divided so that it can be filled with Michigan Lefts.

The larger point was: the zoning boards are the problem.

Every new boulevard is divided because metro Detroit zoning boards design in favor of car use in almost all things. The huge parking lots, the divided neighborhoods, the laughable sidewalk situation -- it's all because optimizing car flow is the priority.

The symptoms aren't the problem.

Worse than any other road that size? It's an eight-lane road and that, by itself, is a big socio/economic dividing force, regardless of the type of intersection.

I think that the commenter is implying that these planning conventions (and the overall mentality of prioritizing car traffic far ahead of pedestrian and bike traffic) go hand in hand with the eight-lane mega-road.

That is correct. I lived there for 3.5 years and now live in downtown Toronto which is the opposite of suburban Detroit in terms of population density and sprawl.

Don't get me wrong, I really love Detroit but its city planning is a huge contributor to its most pressing issues.

Visit Detroit though. It's possibly the most interesting place in the world.

Like these neat random articles? Check out Best of Wikipedia: (http://bestofwikipedia.tumblr.com/)

Usually twice a day, always good. (Not my site, btw)

Cheers.

http://en.wikipedia.org/wiki/Pittsburgh_left

The driving practice of the first left-turning vehicle taking precedence over vehicles going straight through an intersection.

I can confirm that this happens quite often around here. Sometimes, it's fantastic, and alleviates a lot of congestion.

Another odd Pittsburgh-ism that has its own Wikipedia page: http://en.wikipedia.org/wiki/Pittsburgh_parking_chair I'm not a big fan of this one.

This is done in Philly, too, as well as other PA cities. I'd be very surprised if it was limited to PA though

Not to mention that Michigan also puts signs for major intersections before the actual intersection (like 1/4 a mile), but they can be difficult to find (or not even there) at the actual intersection...

It's amazing that there are advantages to this. It seems the main one is the observation that intersections have many overloaded functions which combine to explode the complexity of operations that can occur: intersections handle cross traffic between roads, 4 different points of turning from one road to the orthogonal one via left turn, 4 different points of turning to orthogonal via right turn, four points of u-turns, and pedestrian crossing. Whichever maneuver you pick, there are that many other maneuvers that each other car might be involved in at the same time and you have to interact with. That's an insane level of complexity, and the complexity of the whole system affects all the cars coming from each of 4 directions.

The Michigan turn takes roughly half of these, the 4 left turn modalities and 4 u-turn modalities and displaces each of 4 to a location where it only affects a single direction, the oncoming one, although it has the side effect of doubling the number of right hand turns at the main intersection, but these are safer turns than left ones.

A variation on this I have seen on highways and interstates throughout the US is to have a left turn slow down and two-way median turn around lane that is in between the actual roads where one would turn, ensuring that no dangerous left turns take place. The left turn is replaced with a u turn which is even more dangerous due to the lower speed at which one clears oncoming traffic, and there are seldom any pedestrian situations since pedestrians aren't usually found on highways. But it does avoid the otherwise conflict with negotiating the crossing with several other directions at once, to your right cross traffic, left cross traffic, left across-left turn traffic, right across-left turn traffic, and oncoming traffic, reducing all this to having to deal with oncoming traffic only.

And if I had not read this link I never would have thought about all this stuff, so thanks for posting.

I love that this hit the HN RSS. However, I prefer the Pittsburg Left: http://en.wikipedia.org/wiki/Pittsburgh_Left

These are not related.

also, they are apparently safer than 'normal' left turns: http://news.ncsu.edu/releases/wmshummersuperstreets/

love this habit to give everything a name.

we do this all the time, just didn't call it anyway.

the next time i collide, i'll come out and say, "i gave you a signal, i was making the Pittsburgh left, you uneducated moron!"

See also the Texas Turnaround for highway frontage roads: http://en.wikipedia.org/wiki/Texas_U-turn

I've gotten so used to these, I don't understand why every city with overpasses doesn't have them.

I don't live in Texas anymore and I don't drive anymore, so I never realized this isn't standard around the US. Weird. I loved turnarounds as an option over yielding lefts. You drive a bit further, but it always felt a bit safer, particularly in large strip malls where you have several points of entry along a frontage road.

This is the other type of turn we were discussing at lunch today: http://www.time.com/time/magazine/article/0,9171,2044725,00.....

Did anyone else read this as "the state of Michigan has left wikipedia". Pleasantly surprised at what I found on the link though. I love ideas like this, though I fear majority of drives in the states would have trouble adjusting to this style. They have enough trouble parallel parking and making right's on red, lets not confuse them anymore!

The Michigan left would never work in Massachusetts because of the Boston Sweep (A maneuver in which you merge onto the roadway and rapidly change lanes from far right to far left, without signaling).

I am from Michigan. I hate the Michigan left. It basically puts something between you and the other side of the street. I wonder how much gas I've wasted going right for 1/8 of a mile just to go left.

Probably not much since you'd otherwise waste a lot of gas idling at a red light trying to make a left.

It's not like the "Michigan Left" (I hate that name, "Metro Detroit Left" would be much more accurate) does away with making a left turn at a light. Instead, you make a right turn at light at the intersection, and then a left turn at the extra stoplight they added for the Michigan left. The only time it's really a win is when there's no traffic on the road you're crossing, so you can turn right on red and then left on red. And of course, in that case it would be easy to turn left on green if it were a normal intersection...

These aren't unique to Metro Detroit. Portions of the East Beltline (M-44) in Grand Rapids, one of the busiest streets in the area, make use of the Michigan Left.

Depends on how busy the intersection is. Worst case scenario:

Miss the first light to cross straight through the intersection. Idle.

Queue into the non-intersection left turn lane to cross two lanes of oncoming traffic. Idle.

Wait for a right turn red light and idle, or wait for an opportunity to merge into two lanes of oncoming traffic and idle.

The best case scenario is light traffic and hitting both lights green, but you're still going further and taking longer to accomplish a left turn signal's best case scenario. A double left turn lane with signal is almost always faster in my experience.

As a former Michigander, I would disagree. I miss the Michigan left, I find it's much faster in heavy traffic and makes traffic flow more efficiently.

I'm from Indiana, and I've always found the Michigan left to be much more efficient on busy roads. I alway liked the way they worked while driving in Detroit. For some reason, to me, they made a lot of sense.

Former Michigander here as well. I miss the Michigan Left because it's great for keeping traffic moving with a right on red. However, I am starting to enjoy the ability to U-Turn in most California intersections.

And proud of it!

- A Michigander

Yeah, it makes you feel almost like Columbus!

-Another!

I lived in Bend, Oregon for 3 years and we had roundabouts everywhere. You could literally get across town without stopping at a light/sign.

Maybe they are more of a small/medium sized city feature, but it was hard coming back to California and all it's stop lights and stupid turn lanes.

http://www.ci.bend.or.us/roundabouts/docs/CityEdAug07_Rounda...

I've always been surprised at how living in a different state affects far reaching things such as making left hand turns.

I was more irritated than surprised but yeah - I have thought about this point more than once during my early days in the US.

When I first landed - it was almost frightening to drive -the flashy noisy cop cars, the humongous, wide, structured yet confusing mingling of roads. Then you go drive to another state and few surprises get thrown at you!

Oh and Stop signs really absolutely terminally mean STOP - that took a little while to get used to. I failed driving test due to this - the seriousness of driving tests, that was yet another "O'RLY, FOR REAL?" moment!

I get it all now after several years, but it was fun living through the cross state road trips.

--Another Michigander.

How about those left turn passing lanes on two-lane roads in Maryland? Feels dangerous, but keeps traffic moving.

In Washington, you can turn left onto a one-way street on red. This is legal when you are on a one-way OR two-way street, which is unique to Washington and a handful of other states. This applies to turning left onto freeway on-ramps (one way streets) as well.

left turn to one-way on red is legal in michigan as well, it turns out. having lived in michigan and now washington, I'm glad I learned that this is not the case everywhere before it became an issue.

Wikipedia says left on red from one-way to one-way is legal in 37 states, so you should be good in most places doing that. Alaska, Idaho, Michigan, Oregon, Washington, and B.C. (Canada) allow the left turn from two-way onto one-way as an added bonus.

Flash animation showing examples of East to North and North to West turns - http://www.michigan.gov/documents/mdot/MDOT_Roads-Travel_mic...

Reminded me of this brilliant configuration for avoiding left turns at freeway interchanges:

http://en.wikipedia.org/wiki/Diverging_diamond_interchange

A previous article about another interesting traffic design.

http://news.ycombinator.com/item?id=1437430

These things ALWAYS throw me for a loop when visiting the inlaws. It's so counter-intuitive.

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