In general, urban signal-controlled intersections are just the traffic engineers screaming “I’ve tried nothing and am all out of ideas.”
We use them pretty much by default in the US, but most urban areas should be vastly cutting back on them. All-way stops and, of course, roundabouts are both provably FAR safer often with no impact or a positive impact to overall congestion. Plus, pretty universally much cheaper to build and maintain.
Signal-controlled designs should be reserved for intersections where it is literally not possible to fit a more passive design while maintaining sight distances or for places where truly huge traffic volumes are involved (a significant interchange) where no other traffic flow redesign is possible.
Using traffic lights is ALL about increasing level of service. Which is just code for “The city values keeping more cars moving faster over both safety and financial responsibility.”
All that to say, I bet a lot of the intersections that would be most annoying without right on red… don’t really need to have lights controlling traffic flow in them at all.
Aren’t roundabouts typically significantly larger than an equivalent intersection with traffic lights? If so I’m not sure that’s what we need in urban areas. We already give up so much public space to automobiles. There’s also the question of where does that additional space even come from? Do we bulldoze more homes? To me it seems real solution is to move away from personal vehicles in urban areas. Anything else is just trying to justify an inefficient and unsustainable lifestyle.
They tend to be significantly larger in new construction because small ones don’t really cost a lot less than big ones and most designs prefer to do something nice with the landscaping. Plus, bigger ones flow better. But you can retrofit ones that aren’t vastly larger in size.
All of this is equally true of a road with bike lanes vs one without them… yet cities always seem to be able to find the space, typically by dieting the road a bit. There’s typically lots of options. Narrow lanes, reduce lanes, eliminate some/all on-street parking, cannibalize the median, etc…
Neighborhood traffic circles are a pretty easy drop-in replacement for most of the worst-offender small intersections, too, and they can be achieved with as little as painted lines.
" All-way stops and, of course, roundabouts are both provably FAR safer often with no impact or a positive impact to overall congestion." This is a pretty big statement to make, and I was wondering if you could provide me the sources for this.
“The city values keeping more cars moving faster over both safety and financial responsibility.”
But isn’t keeping cars moving faster financially beneficial? From an energy perspective, needing to stop for every stop sign is way worse on fuel economy than going through a string of green lights and stopping every now and then. Don’t get me wrong, I think using cars as a main mode of transport is incredibly stupid, but I think there must be some tradeoff between time/money/resources wasted due to traffic and time/money/resources lost due to premature deaths or poor living quality due to (non)fatal accidents.
These climate-based arguments for why we should maintain cities primarily designed around the car are just… dumb. Don’t fall victim to them. There is only one effective way to reduce congestion long-term and that is reducing the need for cars. Creating streets that are safe and pleasant for people outside of cars promotes alternatives to driving. And in doing all of this, you’ll have a huge impact on the climate instead of a worthless marginal one.
Road user cost is an EXTREMELY well-studied field with hundreds of complete manuals and textbooks written on the subject. Most states have their own full guidelines. You can very, very directly quantify what the impact of things like work zones is in terms of dollar figures based on theoretical impacts to travelers. So yeah, in those terms, the DOT does put a dollar value on congestion, absolutely. Just as the EPA creates a metric for putting a dollar value on a human life when analyzing impacts of pollution.
The actual traffic study for this would be comparing an intersection with ROR AB tested to without ROR, modeling the increased delay for drivers, and translating that into a figure. A minute or two delay… actually doesn’t amount to very much, and that’s what a typical case would be of forcing a driver to wait an additional cycle. Not to mention that, in a world without ROR, there is no a very good reason to force engineers to do their fucking jobs and design the intersection to work better without that dangerous crutch.
The Philadelphia paper is the seminal work on all way stops being safer than signals in urban contexts. It is pretty definitive and similar studies have confirmed the results, cementing them into most complete streets design guides.
Studies on roundabouts being safer are… even more conclusive and abundant. I really can’t cite just one because damn, there’s so damn many.
“Creating streets that are safe and pleasant for people outside of cars promotes alternatives to driving.” I don’t disagree with this, but the problem is that in the US there often aren’t any alternatives to cars to get around. And to be frank, I’m not gonna be walking around on the streets of LA (where I live, insert your crime-ridden US metropolitan here) unless I have good reason to. Getting hit by a car due to RTOR is the least of my worries as a pedestrian. I think a lot of change is necessary (such as locations of stores, etc) beyond safe streets to reduce the need for cars. For instance, if costs of living in the city were better, people wouldn’t need to use cars to commute. Maybe it’s a starting point to fixing our transportation issue but honestly I don’t see it.
“A minute or two delay… actually doesn’t amount to very much, and that’s what a typical case would be of forcing a driver to wait an additional cycle.” You say this, and it might be the case the vast majority of the time, especially if the stoplights are separated by a large distance and there aren’t many cars, but traffic is a distributed problem and without seeing some sort of study that indicates this I don’t buy into it. During heavy traffic, if the cars from one intersection back up into a previous intersection due to reduced throughput I can’t imagine how an additional cycle is the only cost. Maybe this is just dependent on the traffic situation, because I have a natural bias to think towards traffic situations in LA (which don’t necessarily represent the rest of the US).
“The Philadelphia paper is the seminal work on all way stops being safer than signals in urban contexts.” Can you tell me who the authors of this paper are or maybe offer me a link? I would like to read it, thank you.
“Studies on roundabouts being safer are… even more conclusive and abundant. I really can’t cite just one because damn, there’s so damn many.”
Yeah so I’m pretty sure roundabouts are better in every way except for space. But if only getting more space would be easier, because surely we could just replace a lot of our roads with trains at that point right? I think roundabouts are a red herring because they literally don’t fit in most of these intersections (they don’t even have space for a left turn lane in many of the intersections I drive in). Heck, if we’re talking about space-throughput tradeoffs we could just theoretically make every single intersection a graded interchange and that would provide a huge amount of throughput (but this too is a red herring).
This is the Philly paper. You can explore through its cited bys and references if you want to see the continuing state of the research, but it’s pretty rock-solid. There’s very little doubt in the minds of any policy experts I know of or have read that signaled intersections, in urban contexts, should be used far less. That all-way stops are almost universally a safer design.
Your response on my points about delay is very much just one small problem thinking. I admit, LA’s traffic situation is utterly fucked (thanks to putting the car at the center of all their urban planning for decades, which results in cities that are somehow undriveable AND impossible to navigate outside of cars at the same time). As a person who is immersed in this (and currently published in the TRB, if you can take my word on it because I won’t be doxxing myself), let me assure you: traffic engineers are lazy, unimaginative fuckers. They follow their design manuals like bibles. ROR is easy to execute so they execute it rather than spending the extra 30-40 minutes to include more comprehensive phasing in their proposals. The manuals tell them that’s all they have to and most others are too scared to challenge their “expertise”.
Any traffic system that is going to gridlock because of removal of ROR was misdesigned. Period. Also was probably going to do it anyway, especially as traffic naturally grows over time (outside of the effective policy projects to reduce traffic, e.g., complete streets/multi-modal transportation plans).
If it is low enough volume that it makes sense to have ROR, it shouldn’t have the signal at all.
If it is high enough volume that it risks serious problems if ROR is removed, the ROR almost certainly unsafe to begin with and a dedicated turn signal should be incorporated. Even if it just a signal indicating when it is acceptable to make an unprotected right on red.
ROR is currently the default and “opt-out” in relevant US intersections. It should, at best, be an opt in (e.g., with an arrow indicating you can turn right while yielding during certain phases).
I am not saying all traffic lights should go, but we have far, far, far too many of them. ESPECIALLY in the US, where they basically always have extremely simplistic phasing that, outside of peak rush hour times, simply increases average trip times.
To put it another another way: Braess’s paradox hints at a larger truth: the systems that intuitively seem helpful to prevent congestion are often what CAUSED the congestion. There’s no strong research on AB testing for congestion vs traffic signal removal that I am aware of, unfortunately, because the study is just laden with confounders eliminating any real AB comparison (e.g., making streets safer for multimodal traffic, e.g., by removing signals and replacing with all-way stops, leads to fewer people driving and that may be the “real” reason congestion goes down).
Don’t miss the forest for the trees. Removing right on red is a safety win anywhere you do it. The congestion effects, if and when they even exist, can be addressed through separate system adjustments.
RE: crime… nothing is a better crime deterrent than humans present. My prescription is still to make the streets and neighborhoods more walkable. Adjust policies and designs to get more people comfortable being out there. Not even going to get into challenging the idea that crime is truly on the rise – we both know that it isn’t really.
Roundabouts are pretty cool n and I definitely agree we should use those more (my experience with them is great when people aren’t total morons) but you’re insane if you think 4 way stops don’t affect traffic. Where I live they’ve put in lights now multiple times at intersections like that and it immediately makes traffic better.
my experience with them is great when people aren’t total morons
It really doesn’t matter. They’re safer and better even if – maybe ESPECIALLY if – total morons are going through them. They just change the geometry of how an incident could even happen and leave everyone safer.
In general, urban signal-controlled intersections are just the traffic engineers screaming “I’ve tried nothing and am all out of ideas.”
We use them pretty much by default in the US, but most urban areas should be vastly cutting back on them. All-way stops and, of course, roundabouts are both provably FAR safer often with no impact or a positive impact to overall congestion. Plus, pretty universally much cheaper to build and maintain.
Signal-controlled designs should be reserved for intersections where it is literally not possible to fit a more passive design while maintaining sight distances or for places where truly huge traffic volumes are involved (a significant interchange) where no other traffic flow redesign is possible.
Using traffic lights is ALL about increasing level of service. Which is just code for “The city values keeping more cars moving faster over both safety and financial responsibility.”
All that to say, I bet a lot of the intersections that would be most annoying without right on red… don’t really need to have lights controlling traffic flow in them at all.
Aren’t roundabouts typically significantly larger than an equivalent intersection with traffic lights? If so I’m not sure that’s what we need in urban areas. We already give up so much public space to automobiles. There’s also the question of where does that additional space even come from? Do we bulldoze more homes? To me it seems real solution is to move away from personal vehicles in urban areas. Anything else is just trying to justify an inefficient and unsustainable lifestyle.
They tend to be significantly larger in new construction because small ones don’t really cost a lot less than big ones and most designs prefer to do something nice with the landscaping. Plus, bigger ones flow better. But you can retrofit ones that aren’t vastly larger in size.
All of this is equally true of a road with bike lanes vs one without them… yet cities always seem to be able to find the space, typically by dieting the road a bit. There’s typically lots of options. Narrow lanes, reduce lanes, eliminate some/all on-street parking, cannibalize the median, etc…
Neighborhood traffic circles are a pretty easy drop-in replacement for most of the worst-offender small intersections, too, and they can be achieved with as little as painted lines.
" All-way stops and, of course, roundabouts are both provably FAR safer often with no impact or a positive impact to overall congestion." This is a pretty big statement to make, and I was wondering if you could provide me the sources for this.
“The city values keeping more cars moving faster over both safety and financial responsibility.”
But isn’t keeping cars moving faster financially beneficial? From an energy perspective, needing to stop for every stop sign is way worse on fuel economy than going through a string of green lights and stopping every now and then. Don’t get me wrong, I think using cars as a main mode of transport is incredibly stupid, but I think there must be some tradeoff between time/money/resources wasted due to traffic and time/money/resources lost due to premature deaths or poor living quality due to (non)fatal accidents.
These climate-based arguments for why we should maintain cities primarily designed around the car are just… dumb. Don’t fall victim to them. There is only one effective way to reduce congestion long-term and that is reducing the need for cars. Creating streets that are safe and pleasant for people outside of cars promotes alternatives to driving. And in doing all of this, you’ll have a huge impact on the climate instead of a worthless marginal one.
Road user cost is an EXTREMELY well-studied field with hundreds of complete manuals and textbooks written on the subject. Most states have their own full guidelines. You can very, very directly quantify what the impact of things like work zones is in terms of dollar figures based on theoretical impacts to travelers. So yeah, in those terms, the DOT does put a dollar value on congestion, absolutely. Just as the EPA creates a metric for putting a dollar value on a human life when analyzing impacts of pollution.
The actual traffic study for this would be comparing an intersection with ROR AB tested to without ROR, modeling the increased delay for drivers, and translating that into a figure. A minute or two delay… actually doesn’t amount to very much, and that’s what a typical case would be of forcing a driver to wait an additional cycle. Not to mention that, in a world without ROR, there is no a very good reason to force engineers to do their fucking jobs and design the intersection to work better without that dangerous crutch.
The Philadelphia paper is the seminal work on all way stops being safer than signals in urban contexts. It is pretty definitive and similar studies have confirmed the results, cementing them into most complete streets design guides.
Studies on roundabouts being safer are… even more conclusive and abundant. I really can’t cite just one because damn, there’s so damn many.
“Creating streets that are safe and pleasant for people outside of cars promotes alternatives to driving.” I don’t disagree with this, but the problem is that in the US there often aren’t any alternatives to cars to get around. And to be frank, I’m not gonna be walking around on the streets of LA (where I live, insert your crime-ridden US metropolitan here) unless I have good reason to. Getting hit by a car due to RTOR is the least of my worries as a pedestrian. I think a lot of change is necessary (such as locations of stores, etc) beyond safe streets to reduce the need for cars. For instance, if costs of living in the city were better, people wouldn’t need to use cars to commute. Maybe it’s a starting point to fixing our transportation issue but honestly I don’t see it.
“A minute or two delay… actually doesn’t amount to very much, and that’s what a typical case would be of forcing a driver to wait an additional cycle.” You say this, and it might be the case the vast majority of the time, especially if the stoplights are separated by a large distance and there aren’t many cars, but traffic is a distributed problem and without seeing some sort of study that indicates this I don’t buy into it. During heavy traffic, if the cars from one intersection back up into a previous intersection due to reduced throughput I can’t imagine how an additional cycle is the only cost. Maybe this is just dependent on the traffic situation, because I have a natural bias to think towards traffic situations in LA (which don’t necessarily represent the rest of the US).
“The Philadelphia paper is the seminal work on all way stops being safer than signals in urban contexts.” Can you tell me who the authors of this paper are or maybe offer me a link? I would like to read it, thank you.
“Studies on roundabouts being safer are… even more conclusive and abundant. I really can’t cite just one because damn, there’s so damn many.”
Yeah so I’m pretty sure roundabouts are better in every way except for space. But if only getting more space would be easier, because surely we could just replace a lot of our roads with trains at that point right? I think roundabouts are a red herring because they literally don’t fit in most of these intersections (they don’t even have space for a left turn lane in many of the intersections I drive in). Heck, if we’re talking about space-throughput tradeoffs we could just theoretically make every single intersection a graded interchange and that would provide a huge amount of throughput (but this too is a red herring).
This is the Philly paper. You can explore through its cited bys and references if you want to see the continuing state of the research, but it’s pretty rock-solid. There’s very little doubt in the minds of any policy experts I know of or have read that signaled intersections, in urban contexts, should be used far less. That all-way stops are almost universally a safer design.
Your response on my points about delay is very much just one small problem thinking. I admit, LA’s traffic situation is utterly fucked (thanks to putting the car at the center of all their urban planning for decades, which results in cities that are somehow undriveable AND impossible to navigate outside of cars at the same time). As a person who is immersed in this (and currently published in the TRB, if you can take my word on it because I won’t be doxxing myself), let me assure you: traffic engineers are lazy, unimaginative fuckers. They follow their design manuals like bibles. ROR is easy to execute so they execute it rather than spending the extra 30-40 minutes to include more comprehensive phasing in their proposals. The manuals tell them that’s all they have to and most others are too scared to challenge their “expertise”.
Any traffic system that is going to gridlock because of removal of ROR was misdesigned. Period. Also was probably going to do it anyway, especially as traffic naturally grows over time (outside of the effective policy projects to reduce traffic, e.g., complete streets/multi-modal transportation plans).
If it is low enough volume that it makes sense to have ROR, it shouldn’t have the signal at all.
If it is high enough volume that it risks serious problems if ROR is removed, the ROR almost certainly unsafe to begin with and a dedicated turn signal should be incorporated. Even if it just a signal indicating when it is acceptable to make an unprotected right on red.
ROR is currently the default and “opt-out” in relevant US intersections. It should, at best, be an opt in (e.g., with an arrow indicating you can turn right while yielding during certain phases).
I am not saying all traffic lights should go, but we have far, far, far too many of them. ESPECIALLY in the US, where they basically always have extremely simplistic phasing that, outside of peak rush hour times, simply increases average trip times.
To put it another another way: Braess’s paradox hints at a larger truth: the systems that intuitively seem helpful to prevent congestion are often what CAUSED the congestion. There’s no strong research on AB testing for congestion vs traffic signal removal that I am aware of, unfortunately, because the study is just laden with confounders eliminating any real AB comparison (e.g., making streets safer for multimodal traffic, e.g., by removing signals and replacing with all-way stops, leads to fewer people driving and that may be the “real” reason congestion goes down).
Don’t miss the forest for the trees. Removing right on red is a safety win anywhere you do it. The congestion effects, if and when they even exist, can be addressed through separate system adjustments.
RE: crime… nothing is a better crime deterrent than humans present. My prescription is still to make the streets and neighborhoods more walkable. Adjust policies and designs to get more people comfortable being out there. Not even going to get into challenging the idea that crime is truly on the rise – we both know that it isn’t really.
Roundabouts are pretty cool n and I definitely agree we should use those more (my experience with them is great when people aren’t total morons) but you’re insane if you think 4 way stops don’t affect traffic. Where I live they’ve put in lights now multiple times at intersections like that and it immediately makes traffic better.
It really doesn’t matter. They’re safer and better even if – maybe ESPECIALLY if – total morons are going through them. They just change the geometry of how an incident could even happen and leave everyone safer.