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First Median U-Turn in Florida?

Started by tradephoric, June 05, 2018, 09:58:20 AM

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US 89

Quote from: jakeroot on June 07, 2018, 02:39:52 PM
Cool to hear that a corridor is planned (indeed a necessity for Michigan lefts to work properly).

No one told that to Utah. All of the Michigan lefts here are isolated from any others.

But why is that a necessity? It seems that the Michigan lefts in Utah were implemented to help spread out left-turning traffic. The intersections where they’re used have very high left turn volumes.


jakeroot

Quote from: US 89 on June 07, 2018, 02:47:54 PM
Quote from: jakeroot on June 07, 2018, 02:39:52 PM
Cool to hear that a corridor is planned (indeed a necessity for Michigan lefts to work properly).

No one told that to Utah. All of the Michigan lefts here are isolated from any others.

But why is that a necessity? It seems that the Michigan lefts in Utah were implemented to help spread out left-turning traffic. The intersections where they're used have very high left turn volumes.

I used the wrong terminology. They still work fine without being part of a corridor, but their primary advantage (improving corridor synchronisation) is best achieved when part of a group.

tradephoric

Quote from: US 89 on June 07, 2018, 02:47:54 PM
Quote from: jakeroot on June 07, 2018, 02:39:52 PM
Cool to hear that a corridor is planned (indeed a necessity for Michigan lefts to work properly).
No one told that to Utah. All of the Michigan lefts here are isolated from any others.
But why is that a necessity? It seems that the Michigan lefts in Utah were implemented to help spread out left-turning traffic. The intersections where they're used have very high left turn volumes.

An isolated Michigan left will still improve traffic flow , but the benefit Median U-turns have on signal progression is lost when not applied to an entire corridor.  I will say UDOT has done their best to highlight the improved traffic flow that the isolated Median U-turn intersection has had at 12300 South & Minuteman Drive in Draper, Utah.  UDOT likes to call these Thru Turn intersections just to add to the confusion what these intersections should be called.

https://www.youtube.com/watch?v=kTO5YgVEdxE

Quote from: jakeroot on June 07, 2018, 02:39:52 PMThat image from Oracle & Ina doesn't line up with the operation at Grant & Oracle, though. The U-turns were flashing yellow arrows. Hopefully the plan is for FYAs at these new U-turns and not red arrows. Michigan lefts in Michigan have the advantage of allowing left on red, and I'm certain that helps with flow.

I skimmed over the Grant Road construction plans and there will indeed be flashing yellow arrows at the U-turns.

Quote from: jakeroot on June 07, 2018, 02:39:52 PMHere's a question: why do many Michigan Lefts outside of Michigan allow lefts from one of the arterials? Wouldn't it make better sense for timing if all traffic went through U-turn points?

Many of the Michigan Lefts in Detroit are along wide-8 lane boulevards (ie. Woodward, Telegraph, 8 Mile).  The high number of through lanes helps disperse the Median U-turners along the boulevard and limits the amount of green time required to clear them out once the boulevard gets a green.  Now consider the Ina and Oracle Road MUT in Tuscon.  If the direct lefts didn't exist on Oracle Road and they were diverted to the Ina Road crossovers, those left turners could quickly queue up between the main signal and the crossover (since Ina is only a 4-lane road with limited capacity).  Then potentially the first 30 seconds of the Ina green phase is dedicated to just clearing out those left turners coming from Oracle that now need to continue straight through the intersection.  When left-turning movements are high, it can sometimes make sense to allow direct lefts from the side-street.

tradephoric

Quote from: jakeroot on June 06, 2018, 01:52:54 PM
When I build these intersections in Cities: Skylines, the U-turn movements are yield only. So the only signal is the primary crossover point. It's much easier to build a normal four-way intersection, but building any sort of crossover intersection can usually get me better traffic flow. Although the way the artificial intelligence drives, it's not worth my time at most intersections.

I found this Median U-Turn creation on Cities: Skylines.  Have you seen this one Jake? 
https://www.youtube.com/watch?v=1GC8fvapiVo

jakeroot

Quote from: tradephoric on June 08, 2018, 11:58:28 AM
Quote from: jakeroot on June 06, 2018, 01:52:54 PM
When I build these intersections in Cities: Skylines, the U-turn movements are yield only. So the only signal is the primary crossover point. It's much easier to build a normal four-way intersection, but building any sort of crossover intersection can usually get me better traffic flow. Although the way the artificial intelligence drives, it's not worth my time at most intersections.

I found this Median U-Turn creation on Cities: Skylines.  Have you seen this one Jake? 
https://www.youtube.com/watch?v=1GC8fvapiVo

I hadn't seen this one. He did good work!

If I ever get around to doing another (probably will soon), I will make sure to upload some photos here. My current town is rather small (11k-ish people) so no need for wide roads yet. Widest road right now is a four lane road with the outer lanes for buses only.



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