National Boards > General Highway Talk

Rant: Why aren't Michigan lefts the standard on new arterial streets?

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kernals12:
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?

Max Rockatansky:
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.

SkyPesos:
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.

jeffandnicole:
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.

thspfc:
The fact that they require a larger median is a negative, not a positive.

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