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Author Topic: Two Way Left Turn Lanes  (Read 988 times)

Mapmikey

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Re: Two Way Left Turn Lanes
« Reply #25 on: February 20, 2019, 04:47:11 PM »


It's quite common to see long stretches of center turn lanes in the south in rural areas. I know SC 9 in Lancaster County has a really long one and because it's rather useless, like a lot of these really long ones are, it's often times covered in grass growing through cracks or dirt, this one had small piles (or lumps?) of dirt in the middle on unused stretches. They can also be pretty wide - I've seen some that are as wide as two, maybe two and a half lanes down here.

When South Carolina widened boulevards in suburban areas or even in some rural area starting in the 60s or so, instead of putting a grass median they would have a layer of rough pavement so that drivers could drive across it when making left turns.  This pavement area was not marked and there would be actual left turn lanes at busier locations with pavement just like the through lanes.

They converted these into the TWLTLs when that came along in the early 80s or so by paving them better and marking them.  I have not found a photo that clearly shows one but some historic aerials of the Charleston area confirm they went back a ways in time.

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jakeroot

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Re: Two Way Left Turn Lanes
« Reply #26 on: February 20, 2019, 05:06:07 PM »


It's quite common to see long stretches of center turn lanes in the south in rural areas. I know SC 9 in Lancaster County has a really long one and because it's rather useless, like a lot of these really long ones are, it's often times covered in grass growing through cracks or dirt, this one had small piles (or lumps?) of dirt in the middle on unused stretches. They can also be pretty wide - I've seen some that are as wide as two, maybe two and a half lanes down here.

When South Carolina widened boulevards in suburban areas or even in some rural area starting in the 60s or so, instead of putting a grass median they would have a layer of rough pavement so that drivers could drive across it when making left turns.  This pavement area was not marked and there would be actual left turn lanes at busier locations with pavement just like the through lanes.

They converted these into the TWLTLs when that came along in the early 80s or so by paving them better and marking them.  I have not found a photo that clearly shows one but some historic aerials of the Charleston area confirm they went back a ways in time.

When they eventually went in and marked the TWLTL's, were they pretty wide? Most roads that I can think of that would normally qualify for a grass median, usually have fairly wide medians.
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JREwing78

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Re: Two Way Left Turn Lanes
« Reply #27 on: February 20, 2019, 07:38:19 PM »

Michigan is quite fond of them, particularly in areas that were built up earlier. They will frequently convert 4-lane city streets to 3-lane streets with a TWLTL. Metro Detroit has a number of 7-lane streets (3 lanes in each direction with a TWLTL). Outside of metro Detroit, the 5-lane variety is the rule. Surface roads or streets that need three lanes each way are typically converted to boulevards with a median.

They're less common in Wisconsin; when they do appear, the TWLTL is built extra wide for later conversion to a proper median with left-turn lanes.
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Mapmikey

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Re: Two Way Left Turn Lanes
« Reply #28 on: February 20, 2019, 08:07:47 PM »


It's quite common to see long stretches of center turn lanes in the south in rural areas. I know SC 9 in Lancaster County has a really long one and because it's rather useless, like a lot of these really long ones are, it's often times covered in grass growing through cracks or dirt, this one had small piles (or lumps?) of dirt in the middle on unused stretches. They can also be pretty wide - I've seen some that are as wide as two, maybe two and a half lanes down here.

When South Carolina widened boulevards in suburban areas or even in some rural area starting in the 60s or so, instead of putting a grass median they would have a layer of rough pavement so that drivers could drive across it when making left turns.  This pavement area was not marked and there would be actual left turn lanes at busier locations with pavement just like the through lanes.

They converted these into the TWLTLs when that came along in the early 80s or so by paving them better and marking them.  I have not found a photo that clearly shows one but some historic aerials of the Charleston area confirm they went back a ways in time.

When they eventually went in and marked the TWLTL's, were they pretty wide? Most roads that I can think of that would normally qualify for a grass median, usually have fairly wide medians.

South Carolina had narrow medians on their 4-lane roads in their early days.  There are also numerous pictures of urban/suburban roads that were pretty wide but striped as 4 lanes with no median at all that later went to TWLTL...

Here is an example of a road widened in the late 1930s that had a grass median anywhere you see asphalt in the middle.  They striped the center lane a little smaller than the median presumably to give the travel lanes a bit more space:  https://goo.gl/maps/aVXX2FHJxnt

This one also in the Charleston area wasn't widened until the early 60s and AFAIK had no grass median - https://goo.gl/maps/NYsfebWZJyA2

Here is one that was widened to 4-lanes undivided in the 1940s and was recently converted to 3 lane with TWLTL - https://goo.gl/maps/7VEckTf7Q482

I'm annoyed I cannot locate an online photo of a divided road in SC with the rough paved medians that were everywhere...
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kphoger

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Re: Two Way Left Turn Lanes
« Reply #29 on: February 21, 2019, 02:40:03 PM »

I'd much rather find my gap in both directions of traffic traffic and do the turn in one motion, instead of finding a gap in traffic from the left, possibly sitting in the middle, and then merging into a gap in traffic from the right. Also, I've always experienced a bit of anxiety being the driver on the main street and not knowing if that car coming from the side street/driveway is actually turning into the TWLTL as I'd expect, or if they're erroneously turning into my lane... It's happened to me more than once.

So I don't like to put other drivers in that situation if I can avoid it. Thus, I only turn into the TWLTL when it's pretty obvious that the volume of cross traffic isn't going to allow a one-stage left turn.

FWIW, it's doesn't seem to be a super common maneuver in Nevada...

This describes my take on things as well.  I use the TWTL when I need to because of heavy traffic, and I wait for a gap in both directions otherwise.
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