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Old 01-14-2015, 12:12 PM
 
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Quote:
Originally Posted by impala096 View Post
The theory is there has been a shift away from one-way couplets because many American cities have been in decline. City streets are being downsized to match the declining population densities. That appears to be the case with 2nd Avenue in Detroit. The Avenue is entirely too wide for the traffic it receives, but had Detroit gained 1.2 million people since 1950 as opposed to lose it, 2nd Avenue would look much different today. Converting 2nd Avenue to a two-way street is an indictment of Detroit.
And for many cities, this will prove to be utter folly. As more residential units are built in the central city, and in many cities that is happening now, there will be much more traffic coming. Even if the residents of the central city entirely walk or ride bicycles in their central city, they will still drive to and from other cities, or other parts of the same city.

And let us not forget the environment. Gridlocked, stop-sign-to-stop-sign automobiles create twice the NOx contaminants and six times the carbon contaminants per mile as those operating at peak efficiency. Think about that. Simply adding more stoplights, metered to a 25 to 30 mph pace in order to punish speeders would be better for air quality than having the cars creep from stop sign to stop sign.

And non synchronized lights cause drivers to madly dash from one block to the next.
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Old 01-14-2015, 12:13 PM
 
Location: Portland, Oregon
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Quote:
Originally Posted by impala096 View Post
The theory is there has been a shift away from one-way couplets because many American cities have been in decline. City streets are being downsized to match the declining population densities. That appears to be the case with 2nd Avenue in Detroit. The Avenue is entirely too wide for the traffic it receives, but had Detroit gained 1.2 million people since 1950 as opposed to lose it, 2nd Avenue would look much different today. Converting 2nd Avenue to a two-way street is an indictment of Detroit.
It depends on the street size, couplets in Portland tend to make sense because we have narrow streets. When a street that is a wide avenue is converted to a couplet, those streets are created to move cars through an area rather than stimulate commercial activity.
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Old 01-14-2015, 12:35 PM
 
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Quote:
Originally Posted by urbanlife78 View Post
It depends on the street size, couplets in Portland tend to make sense because we have narrow streets. When a street that is a wide avenue is converted to a couplet, those streets are created to move cars through an area rather than stimulate commercial activity.
It also depends on traffic density and speed and context. A broad one-way street, with proper signal timing and spacing, and/or with lane narrowing and other speed-calming measures, can serve both purposes by moving a lot of vehicles slowly (25-35 MPG) but steadily, with little if any idling at stops and lights.
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Old 01-14-2015, 12:59 PM
 
Location: Portland, Oregon
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Quote:
Originally Posted by darkeconomist View Post
It also depends on traffic density and speed and context. A broad one-way street, with proper signal timing and spacing, and/or with lane narrowing and other speed-calming measures, can serve both purposes by moving a lot of vehicles slowly (25-35 MPG) but steadily, with little if any idling at stops and lights.
That is also true, though more often than not, a large one way road is used to move traffic through at a faster speed.
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Old 01-14-2015, 03:30 PM
 
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A one-way street can be safer for pedestrians and provide a better pedestrian experience.

1. A one-way street lowers the pedestrians risk exposure. Assuming the lowest capacity for each street type, a pedestrian crosses one-lane of moving traffic at a one-way street compared to two-lanes of moving traffic at a two-way street. The pedestrian’s risk exposure is doubled when crossing a two-way street.

2. There are fewer pedestrian conflict points at a one-way street crossing. Essentially, there are fewer ways a pedestrian can get hit when crossing at a one-way street.

3. The speed of traffic can be lower on a one-way street since the traffic signals can be timed for a set speed. In the case of Portland, the city times the downtown one-ways for 12 mph. But what about when there isn’t any traffic signals to regulate the speed of traffic? Traffic calming measures can be applied to both one-way and two way streets and there is ZERO indication that the speed of traffic would differ between the two.

4. A one-way street can reduce the distance between buildings and improve the pedestrian experience. The lowest capacity two-way street requires twice as much ROW (and twice the distance) as the lowest capacity one-way street.

5. Empirical data spanning the past 60 years suggests that one-way streets are safer for pedestrians than two-way streets. The “Chinatown One-Way Street Conversion Study”, published in 2009, includes a literature review summarizing twenty-seven different journal articles relevant to the topic.
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Old 01-14-2015, 03:39 PM
 
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Consider Franklin Street in Juneau, Alaska. It illustrates the lowest capacity one-way street to the lowest capacity two-way street.

Franklin Street (One-way section):



Franklin Street (Two-way section):
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Old 01-15-2015, 04:02 PM
 
409 posts, read 388,635 times
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Quote:
Originally Posted by NickB1967 View Post
And let us not forget the environment. Gridlocked, stop-sign-to-stop-sign automobiles create twice the NOx contaminants and six times the carbon contaminants per mile as those operating at peak efficiency. Think about that. Simply adding more stoplights, metered to a 25 to 30 mph pace in order to punish speeders would be better for air quality than having the cars creep from stop sign to stop sign.
Those are some good points. Speeders may not like it, but a well timed one-way street benefits nearly everybody else. Some of the main benefits of a one-way street:

-lower CO2 emissions.
-slower operating speeds (drivers limited to the speed of the green wave).
-faster travel times for both drivers and transit users (due to less delay at red lights).
-fewer pedestrian conflicts leading to fewer pedestrian accidents.
-narrower streets (a one-way street has more potential to be narrower than any two-way street).
-shorter cycle lengths at traffic signals, leading to lower delay for pedestrians (since one-way streets don't require inefficient left-turn phases).
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Old 01-20-2015, 04:16 PM
 
Location: Oakland, CA
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I live on one. Each street is about 2-3 lanes depending on where, and then is 2 way at either end. It is actually much more dangerous in my mostly residential area. It is fairly dense, and the area is bisected by a freeway. There is a school at the end of the couplet in a 2 way section. The 2 way resumes about 2 blocks from my apartment, the couplet lasts roughly 1 mile.

What happens is cars are speeding to or from the freeway. The speed limit is 30, cars regularly travel 40, but with the driveways and density and bus stops and bike lanes the speed limit should be 20.

It is actually pretty annoying, but this couplet is pretty permanent. It was created by a street car.
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Old 01-21-2015, 11:00 AM
 
2,553 posts, read 2,003,488 times
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Quote:
Originally Posted by jade408 View Post
I live on one. Each street is about 2-3 lanes depending on where, and then is 2 way at either end. It is actually much more dangerous in my mostly residential area. It is fairly dense, and the area is bisected by a freeway. There is a school at the end of the couplet in a 2 way section. The 2 way resumes about 2 blocks from my apartment, the couplet lasts roughly 1 mile.

What happens is cars are speeding to or from the freeway. The speed limit is 30, cars regularly travel 40, but with the driveways and density and bus stops and bike lanes the speed limit should be 20.

It is actually pretty annoying, but this couplet is pretty permanent. It was created by a street car.
Your description suggests the problem of safety is not a matter of the couplet, but instead is a problem of the proximity to a freeway and of poor flow management (ie, signal timing and coordination). Speed limits are idiotic things; people will drive based upon contextual cues, regardless of posted limit or threat of tickets.
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Old 09-17-2015, 10:04 PM
 
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Default Yeah! A few couplet fans!

I just noticed this thread. I am the founder of Metro Analytics, and looks like I indirectly kicked off this discussion of couplets with my Top 10 Advantages of couplets paper. (http://www.metroanalytics.com/_Downl...20Couplets.pdf)

I'm glad there are a few fans out there who "get it". People dismiss them too easily, thinking they "create high speeds" and other maladies. But speeds are a function of design, and have nothing to do with one-way or two-way. As I noted and many of you did too, speeds are more likely to be lower if that's what the city desires, because they can control the speed of the green wave and virtually everyone will comply.

Another thing I love is that you can eliminate center-turn lanes. The purpose of these center lanes is for storing traffic that is waiting for oncoming traffic to pass so they can turn left. But if there is no oncoming traffic, then there is no need for this 14 foot dead space! So redistribute it in the form of a better pedestrian environment, on-street parking, or whatever you want to do.

If any of you get notice of my post, I'd love to continue the discussion!
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