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Might want to fill in the details for the non-traffic engineers...
Should be in "Great Debates" -- this is like a "holy war" with some folks vehemently opposed to the idea of "dual one way streets in opposite directions as a means of enhancing downtowns"...
...because a driver is riding a green wave, the propagation (speed) of which can be fine tuned.
Here are some examples of the green wave in action.
6th Avenue – Portland, Oregon (timed for 12 MPH):
1st Avenue – NYC (timed for 27.5 MPH):
An aggressive driver may feel comfortable traveling through downtown Portland at 40 mph. That same aggressive driver will quickly find themselves putzing along at 12 mph once they realize they can't outrun the green wave. That's a 70% reduction in speed.
The green wave can be tweaked as needed. If there a sudden increase in pedestrian injury accidents along 1st Avenue, NYC could decide to retime the traffic signals for a slower speed in an attempt to improve pedestrian safety.
One-way couplets are an idea that has come and gone. Imagine that Fifth Avenue is the main drag. Perhaps Fourth Avenue runs for about a mile. Converting these two into a couplet requires improvements on Fourth to the level of Fifth. And of course commercial property on Fourth becomes more valuable, at the expense of that on Fifth. And of course the traffic relief only extends for the length of the one-way couplet.
And of course the traffic relief only extends for the length of the one-way couplet.
...which may be the point (or, at least, all that's necessary) if a commercial area has the (seemingly) competing demands for traffic volume and pedestrian safety. Take a look at downtown Campbell, CA. It's small, but it makes the point.
“The new trend is away from couplets!”
America’s downtowns used to be thriving. Many implemented couplets as a way to accommodate more vehicles within the same right-of-way. As demand fled to the suburbs, the need to move vehicles has greatly diminished in many downtowns. If you don’t have traffic problems and aren’t anticipating a new wave of mixed-use development, reverting to two-way may be best for you.
Detroit has lost 63% of its population over the past six decades, going from 1.85 million people in 1950 down to 688,000 people today. The city recently converted 2nd Avenue to a two-way street, downsizing the capacity to match current traffic demands. Should the conversion of 2nd Avenue be viewed as a model for success or an acknowledgement of failure?
Detroit has lost 63% of its population over the past six decades, going from 1.85 million people in 1950 down to 688,000 people today. The city recently converted 2nd Avenue to a two-way street, downsizing the capacity to match current traffic demands. Should the conversion of 2nd Avenue be viewed as a model for success or an acknowledgement of failure?
2nd Avenue (@ Caniff, 1929)
2nd Avenue (pre-2014)
2nd Avenue (post-2014)
A couple of issues come to mind.
First of all, that avenue is much too wide and, assuming it is like similar-looking roadways with which I am familiar, probably much too fast for a dense commercial area. An area can have wide avenues and be commercially successful, but it requires a certain minimum of traffic density and maximum of traffic speed. Else, the model for commercial success shifts away from pedestrian-oriented to strip mall.
Second, the hollowing out of Detroit probably meant that the conversion made sense when measured by a variety of metrics--maintenance costs, pedestrian safety, land value, etc. But that need for a change is a function of the context of that location, not an indictment of the one-way couplet model.
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.
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Might want to fill in the details for the non-traffic engineers...
