Why Traffic Congestion Grows Exponentially, Why It Matters, and What To Do About It // An Explainer

[@NotJustBikes]

This is probably the best explanation of this phenomenon that I've seen. I'm going to refer to this in a future video for sure. One of the most frustrating "objections" when it comes to alternatives to driving is that many people need to drive, and (today at least) there may be few people who can take advantage of these alternatives in a car-dependent city. It's annoying that this "objection" ignores future travel demand, but it's even more frustrating because you actually only need to take a small number of cars off of the road to make a hugely positive difference to congestion. You didn't quite say it in this language in this video, but you hinted at it: the difference between free-flowing traffic and stop-and-go traffic can literally be just a few cars. Which means that even if, say, a dozen rush hour drivers cycle instead, it can have a massive contribution to better traffic flow. I recently made a video about how driving is awesome in the Netherlands, but I have a feeling that most suburbanites are never going to understand this. Edit: by the way I searched for lazer dix on my channel and he's a car enthusiast who was triggered by my noise video. Some of these people do not appreciate being reminded of what the damage their "hobby" causes to society, and when somebody does, they try to paint them as irrational car-haters. There will always be selfish people who want to stand in the way of progress, but that's why we need to keep fighting for better cities.

[@Nukepositive]

There's really three dimensions to changing car-brain: buildings, streets, and vehicles. We need to show them how all three work together to make a new living space. Zoning, street design, and new vehicles they may not have heard of like e-bikes, cargo bikes, trams, light rail, and others are part of a great urban landscape.

[@m1nekji165]

@@lazerdx wow you really got burned here, lol

[@davgg9621]

@@lazerdx bro, everything is politics. Wake up.

[@pappy9473]

@@lazerdx Wow. Keep your shirt on pal. Maybe 'Not Just Bikes' is not professional enough for you but he's often humorous and gets his point across in a non-conflicting manner. Which is more than can be said for those who fly off the handle (bars). 😆

[@lazerdx]

@@pappy9473 The quality of his content is not what I was complaining about in the slightest, and for the record his passive aggressiveness in comments makes me look like Mother Theresa (the idealized version, not the real one).

[@hdog679]

"You are the congestion." That might be the single biggest eye-opener here.

[@CityNerd]

It's a time-worn phrase in transportation planning circles, but it's true enough to justify big font.

[@Penfold497]

So make the cycle eight seconds. Duh.

[@a2dsouza]

This is your best one yet, by far. I'm sure these kinds of videos take significantly more effort than the top 10 lists, but this is the one that made me subscribe. Keep it up!

[@CityNerd]

Thanks, I appreciate it!

[@TheGrinningSkull]

Same for me!

[@raulterronez3789]

agree

[@notthedroidsyourelookingfo4026]

@@CityNerd Does it actually require more effort than a top 10 list? With the research you put into those lists, I wasn't sure..

[@harrywoodman2988]

@@CityNerd I would love to see a video on how commute time affects lower income families as they get pushed out of the city centers. It's a serious problem in cities like SF

[@dontgetlost4078]

That first possible solution is more or less the one everyone think will work: "1 more lane will do the trick!" It just makes the cities even worse for pedestrians with massive stroads and these intersections so large that even with pedestrian traffic on crossing it is basically suicide.

[@stephengray1344]

And the adding one more lane also runs into the issue of induced demand. The easier it is to make a particular journey, the more people make that journey. So you add one more lane, then find that a couple of years later the congestion is just as bad as it was before because the extra lane means that more people are driving on that particular stroad.

[@rhebucks_zh]

it must be a bike crossing to not commit suicide

[@ShubhamMishrabro]

I can agree. I have to cross 8 lane road and it scares me

[@mkkm945]

This is also kind of why airport security lines (for example) appear either empty or backed up significantly. When the system is at or just below capacity, all is empty. When it's just 20-30% over capacity, it's 100% lined up.

[@CityNerd]

Another good example! Someone else mentioned elevator banks at peak demand.

[@kevinlove4356]

It has been my experience that cities which have successfully eliminated or seriously reduced traffic congestion have used none of the solutions mentioned in the video. Instead they have implemented measures that make walking, cycling or public transit the fastest, easiest and most convenient way of safely going from A to B. I will give three examples. The first is Groningen in The Netherlands. This uses a neighbourhood zone strategy. This means that people walking, cycling and using public transit can go straight from A to B. But concrete and steel barriers prevent private automobile drivers from going directly from one zone to an adjacent zone. For private automobile drivers to go from one zone to the next, they must drive out of the zone to the surrounding ring road. Then drive around the ring road to the outer edge of the zone in which their destination lies. Then drive in through the zone to their destination. This has the effect of making walking, cycling or public transit the fastest, easiest and most convenient way of going safely from A to B for a very large percentage of trips in Groningen. The second example is Ghent, Belgium. The introduction of its Traffic Circulation Plan put affected streets into three categories. Category 1 Car-free. Category 2: Motor vehicles are restricted to local residents, local merchants and their suppliers, public transit vehicles, taxis and emergency vehicles. Category 3: A neighbourhood zone strategy, similar to the above one for Groningen. Ghent's Traffic Circulation Plan resulted in rmaking walking, cycling or public transit the fastest, easiest and most convenient way of going safely from A to B for a very large percentage of trips in Ghent. The third example is the city of Utrecht in The Netherlands. It has an extensive car-free downtown. The motorway that was built upon the city moat was removed and the moat restored. And on other streets, there has been a steady shift in use that took away space that was previously used by motor vehicles in order to create fantastic cycling infrastructure. Once again, the effect has been to make walking, cycling or public transit the fastest, easiest and most convenient way of going safely from A to B for a very large percentage of trips in Groningen. I strongly disagree with the statement: "Every city has problems with growing traffic congestion." These three cities do not, and neither do many other cities around the world. The one thing that they tend to have in common are measures that make walking, cycling or public transit the fastest, easiest and most convenient way of safely going from A to B. I highly recommend Mark Wagonbuur's blog, "Dutch Cycling." It provides an excellent description of Utrecht and many other places in The Netherlands.

[@lb2791]

True! You can't just make driving less accessible with congestion pricing without delivering better infrastructure for the alternatives. Also, cars are just an extremely space-inefficient mode of transportation that's not suitable for cities because of the limited space available. Every city where the main mode of transportation is cars will have congestion issues. The solution is using more space efficient modes of transportation.

[@kevinlove4356]

@@lb2791 Very true. In cities where the main mode of transportation is the bicycle, it would be impossible to start using automobiles for transportation. The laws of geometry dictate that there just is not enough space to put that many large metal boxes on the street. It is annoying that KZbin no longer allows me to post links. Mark Wagonbuur has produced an excellent video of Vredenburg in Utrecht for his "Bicycle Dutch" blog. This street is used by 32,000 people on bicycles each day. It would be impossible for them to start using automobiles. Just not enough street space. Or space for automobile parking. One of the most fascinating parts of the video is the "before and after" shots. Before the street went car-free, it was a nightmare of congestion. Now traffic flows freely. Please search with KZbin's search function on "Bicycle Vredenburg."

[@lb2791]

kzbin.info/www/bejne/nYDPZql8bdFqfMU

[@lb2791]

Great example! A car lane could move 1/20 of that amount in people.

[@kevinlove4356]

@@lb2791 Also see: kzbin.info/www/bejne/r5_afoFpj56CnZo Hey! My link showed up!

[@benphillippi3075]

i like how tight you edit your episodes. not a word wasted in 12 minutes. Impeccable!

[@connecticutmultimodaltrans8226]

Wow, this was an awesome video! I really can tell you spent a lot of time on this, especially the graphics. What did you use to make those? I'd love to see more of these style. Exciting to see this channel growing!

[@CityNerd]

My graphics studio is top secret! I have a crack team of underpaid keyboard jockeys sequestered at a Black Site, toiling away with limited food and water on hand. Need-to-know basis!

[@hotbeefo]

@@CityNerd is it perhaps your own children being put to work? 😂 I always value that you respond to comments, it adds a lot to these videos.

[@mrgeorgejetson]

Great video. Also, I want to add to the voices encouraging you to do more along these lines, in terms of video structure. The top 10 lists are entertaining (and possibly useful for somebody considering a move), but stuff like this is way more interesting and rewarding.

[@Knackebrot]

Honestly one of your best videos. Needs more views.

[@victotronics]

Brilliant presentation. Quantitative analysis always convinces me more than hand-waving qualitative arguments.

[@reginaldphillips7615]

More of this kind of content please. Also, if you could discuss bus bunching in the same manner, that would be great!

[@Simon-tc1mc]

Really shows how car pooling and taking transit makes a difference. Great video. I don't get why all these city planners suggest fees though for driving. That's not really fair as it punishes the poor and those who don't live close to where they need to be.

[@Simon-tc1mc]

@Zaydan Naufal yeah of course, but that isn't always available. Car pooling isn't great but at least it's one more car off that road.

[@dpeastman]

Your top 10 videos are good... But I really like these explainer videos even more. I especially like connecting the engineering issues with the policy issues.

[@CityNerd]

I like it too -- they're harder to make, partly because the graphics are more time consuming, but also the amount of time I have to spend thinking through and triple checking all my calculations. I'll definitely make these kinds of vids a regular feature though.

[@dpeastman]

@@CityNerd That makes sense... Consider this a note of appreciation for your hard work.

[@haroldbrown6184]

I have been a big supporter of congestion pricing. I live in NYC. Congestion pricing is scheduled to begin in NYC next spring. I have a lot of concerns about the way it is being rolled out. How NYC handles congestion pricing is going to be very important for its future in the U.S. I think it would be great if you did a video on NYC congestion pricing.

[@riblets1968]

Re congestion pricing: it's interesting that you make the point to make people pay more to drive at peak times. I like this approach because it incentivizes folks to drive at other, lower volume times should they have the choice to do so. Dr. Walter Block made this very point some decades ago in a number of papers, and a book that he wrote on the topic of roads, or as Block calls it, "socialist roads," alluding to the classic problem of Tragedy of the Commons. Mind you, Block's training is in economics, but I think he makes a number of good points. Anywho, I found this to be very instructive in just how fragile our urban road infrastructure is in terms of actually conducting traffic.

[@dcseain]

On Memorial Day, thanks to a closed road, from the point i first stopped, it was the fourth light cycle before i completed my left turn in Vienna, VA,

[@jonathankleinow2073]

As a former resident of Southwest Florida, I can confidently say that adding additional lanes in order to alleviate congestion is definitely a cheap and reliable way to make sure there are never any delays and that every driver is happy and calm. **twitches**

[@CityNerd]

Ft Myers' transportation system kinda blew me away when I visited a couple years ago. Sanibel and Captiva are pretty cool, though!

[@jonathankleinow2073]

@@CityNerd I lived on Sanibel when I was in high school and was able to move back with my family for a few years. Sanibel is really lovely, and they've done a good job of keeping the commercialization to a minimum. I remember the "McStop" campaign of the mid-90s, when McDonald's wanted to build a restaurant on the island and made all these modifications to the plans to adapt it so it would blend in, but the residents kept it from happening. The only chains are Subway and Dairy Queen, and they were there before the city was founded in 1974.

[@somedudejared]

Fantastic video! Great insight! Love the technical outlook on the problem!

[@ultraNewt]

watching that little animation at 2:10 was pain, because deep down I know it's timed realistically

[@stevengordon3271]

Or just disallow left turns (everybody has to turn right 3 times instead). Of course, left hand arrow turns was just an example.

[@somedudejared]

This video makes me want to change to biking to work, but I live in Phoenix 🤮 the least walkable/bikeable city in the country! An average 20 mile commute is just too far to bike

[@CityNerd]

That would be tough! Phoenix has some things going for it, but bikeability isn't one of them.

[@bhatkrishnakishor]

As a driver you perceive congestion is happening to you, but in reality you are the congestion. 👍

[@dougwedel9484]

Traffic planners focus on reducing car traffic congestion. But I don't know of any bike lanes which get maxed out. In fact, I don't know what the maximum capacity for a bike lane is. This can be measured by how many bicycles can go past one spot on a route with a bike lane every hour, how many can be typical for a day (all travel routes seem underused at night so saturation at peak demand still seems the most important factor). Then once you get a bike lane fully saturated, the surplus demand flows into other times and routes, like what they talk about with the induced demand discussions for cars, for adding lanes for a highway. I'm not aware of any cyclists who say, I never take a bike lane because there are too many cyclists and it takes me too long to use that route. It may happen in future but I never hear of it at this time (or ever before). So far, in Toronto, people talk about how the Martin Goodman Trail gets incredibly busy on summer weekends. But I never hear people say they avoid that route at peak times. Even shy bicyclists who typically shun crowds, like in malls or stadiums. I have the crazy idea... bike lanes are not an incentive to ride a bicycle, they remove disincentives to bike. People avoid streets without bike lanes because they are dangerous and because they get harassed by drivers (honking, yelling, aggressive stunts like close passes, etc.). So actually to get technical, bike lanes are a double negative twice (they remove both the hassles and the danger from mixing with cars in their lanes). So they are a quadruple negative passing themselves off as two positives? My point is, bike lanes are not positive reasons to ride a bicycle in and of themselves. But what are positive reasons to bike? Fresh air, feeling of freedom, more friendly (when you don't get yelled at), less anonymous (how often do you take a bus and wave at your friend riding in another bus?), they encourage more trees, which makes a streetscape feel more friendly. They are healthier for cyclists, for the environment, for others (fewer traffic injuries or fatalities), increase what people call physical literacy (the ability to control our body, balance, etc), learn way finding, have a sense of independence. It's much cheaper $, you can more likely be able to fix your bicycle yourself vs be able to fix a car. This is important to work out because demand for driving cars exceeds supply... by a lot. Demand to take the bus and subway is about equal to supply, but demand for riding bicycles in North America is much lower than the supply or the potential to supply the ability to ride bikes. If we ever want to address traffic congestion with cars, we need to look at demand for cars and for alternatives like transit and bicycling (and walking). If we don't, then we will always focus on creating disincentives to drive, things like congestion pricing. We don't really take on the issue of car congestion if we don't talk frankly and in-depth about what creates demand for cars and bikes and buses in a first principles way (to quote the car maker Elon Musk).

[@jonpata9869]

I work in software and an when code runs exponentially slower as input size grows, that very very bad. That's all about scalability of solutions. It was just a funny similarity I noticed between my work world and traffic congestion

[@AlRoderick]

And it's for a lot of the same reason, computer architecture can be compared to a city transportation system. Registers and cache are local to the processor core where the work is done, but that's in limited supply so you have to have data commuting in and out from the ram, which can cause delays.

[@CityNerd]

Super interesting point!

[@r.williams8349]

great video. yes please to the congestion pricing video!

[@derbagger22]

I still don't understand why most people can't accelerate from a stop more quickly. I don't care if I'm car #1 or #30, the moment that light goes green, the pressure of my right foot on the brake is lightening. The millisecond the car in front of me moves, I do the same. All the while I am never at a rate of acceleration greater than the car in front of me. And since a car would have to not only slow its acceleration, but then decelerate before I could close that gap, I have all the time in the world to react. As for people saying, "oh look at city________ in Europe, we're not Europe. We don't have the ancient, tiny cities that Europe has and very few US cities can do what Europe does. This country is very large, very vast and very car centric. The best way to actually improve our traffic is to have better teaching of new drivers, constant courses for all drivers and more stringent testing. I see much more traffic caused on weekends by fewer, lackadaisical out of state drivers than I do by hordes of commuters on a weekday.

[@TimothyHalkowski]

Good explanation!

[@rlrober]

Hi CityNerd.......another suggestion. How about comparing parking between cities ? Some cities embrace parking while others are hostile. Expensive vs Free ? Parking requirements for businesses ? Some are NOTORIOUS for towing. Making a video about parking could inform your viewers what to expect when traveling to a city by car.

[@CityNerd]

I'm definitely interested in doing something like this. Thanks!

[@UnipornFrumm]

I driven in romania and there was a 3 lane 4 exit roundabout at the city entrance i think. It was full of cars,full,probably worst time of day to drive,whole city was full of cars(comunist city,high dencity residential apartaments,little parking not designed for huge amounts of cars)and 0 trafic lights at this roundabout,nobody was giving way because if they did nobody would enter the roundabout,chaos,everybody had to enter the roundabout without giving priority. I think trafic lights would fix this,at least lights that turn on when more cars drive trough there. But i m no expert.

[@Droxal]

Please do a video on congestion pricing!!!

[@paxundpeace9970]

Smart traffic light like they get used in Europe can increase capacity. It either cut the left turn cycle or is able to increase the length.

[@CityNerd]

They have these in the US, too. I tried to keep this simplified, but also, this is actually based on an actual intersection I'm intimately familiar with where the left turn is from the minor street, and all the green extensions, etc., get applied to the cross-traffic, which is on a coordinated system so the cycle has to be maintained. Your point is a good one, though.

[@gasmaster8437]

Man it's so complex and scales so badly. It's almost like private cars are a inefficient, unreliable, and unsustainable approach to moving people. Luckily they don't also have a bunch of dangerous externalities or consume lamd with a voracious appetite, or we'd really be dumb for building society around them.

[@zeroone8800]

But is it in fact exponential? Is the rate of growth proportional to the current value? Many claim effects are exponential when they might be quadratic or some other power function. Exponential does not mean greater than linear; it means the rate of change is proportional to itself.

[@Contreramanjaro]

I think it's more just creative hyperbole since the actual rate of traffic is unpredictable, Not to mention the ability for people to pick other routes, run red lights, have trailers, etc. I doubt you would ever see a clean exponential curve.

[@darkfuji196]

It's actually quadratic by the looks of it (each overflow car in the worst case increases the average wait by period/cars_per_period), but I'm pretty sure that was just hyperbole.

[@BHFJohnny]

Huh. I wanted to ask something in a way "As someone totally ignorant of the topic who just starts scratching the surface, wouldn't setting some price on actually going to city help?". And here we go, answer in the same video 🤔

[@carytodd7211]

Excellent video.

[@ieliemielio]

Love these mathy videos! But couldn’t these stochastic problems be greatly reduced by inductive loop detectors? How about a video on the top 10 smartest intersections?

[@alcubierrevj]

Well thought out video and love the stochastic approach to the traffic modeling that actually lead to realistic conclusions. In fact, I thoroughly enjoyed the video until you said I was the traffic! 🤣🤣🤣

[@CityNerd]

Yeah, the stochastic approach is sort of useless if I want to do a mathematical proof, but pretty good for illustrating a problem in a way more people can actually grasp.

[@thechikage1091]

So this why my commute to work can range anywhere between 25 and 45 minutes depending on how many construction vehicles are in front of me.

[@jonathansy4552]

I've been meaning to create this exact simulation you've done so I could verify my intuition that traffic is exponential. Thanks for the awesome explainer and visuals! btw: is there any chance you upload the code you used in your simulation so others could perhaps play around with it or modify it? totally cool if you don't have time for it though!

[@CityNerd]

I've toyed with the idea of cleaning up my spreadsheets/macros for sharing...but it seems daunting when I have competing demands on my time. Will consider it, though.

[@TheNotverysocial]

Not everyone works in construction. Those who do not should work at home, and it should be an option, eradicate an unnecessary commute. That would ease things for those who do repave the roads/streets, and other such jobs. Not everyone in that gridlock needs to be there, and that makes it worse. As for me, I take the residential streets to work, for I do not live far enough away to justify freeways. Nor drive motor vehicles. I take my bicycle. An inexpensive way to stay healthy.

[@TABarnhart]

what i see here in Portland (and surrounding burbs) is that 3-5 cars run each & every red light on the left turn. so through traffic is delayed a bit more. (also, you should look at how people "stop" at lights: there's almost always a full car length or more between cars. that reduces even more how many cars get through a light. bottom line: humans suck at driving.)

[@Notthecobracommander]

I agree we need more toll roads that are not directly connected to the road that they bypass on a constant basis toll Lanes don't work separate toll roads do. Then use whatever money is generated as you said to help improve public transit and regular Transit. It's why Dallas Texas was a much easier City to drive through then Atlanta Georgia.

[@dandugan1131]

Can you do an analysis like this for transit options? Also would smarter traffic lights somewhat reduce this problem?

[@CityNerd]

Early greens and green extensions can help with a traffic problem like what I illustrated here.

[@adamt195]

The graphics are really good in this video.

[@CityNerd]

They're...OK.

[@JiminyClarkson]

To put it this way, the longer you are stuck in traffic, the longer you are also taking up a road space and causing others behind you to be stuck in traffic.

[@chrisg8995]

We’re going to have to adopt some kind of model similar to congestion pricing as EV adoption grows. So much of our transpo infrastructure is funded by taxes at the gas pump. EV drivers are essentially driving for free right now, enjoy it while it lasts.

[@MilanStojakov]

Solution is to replace traffic lights with roundabouts and increase speed limit.

[@Santiago8041]

Thanks!

[@CityNerd]

Thanks a lot!

[@Sp4mMe]

Congestion pricing I only experienced from Italian cities and let's say I have my reservation about their implementation, but wouldn't it be just another slap in the face of poorer neighborhoods / people in the US? If you have a functioning public network, sure, we can talk about whether driving should be a privilege tied to your purse*, like all those other privileges richer people already have. But when cars are your main reasonable way to get to a job that sounds socially problematic to me ... *I'd prefer having it tied to something else, like perhaps your carbon footprint or your, uh, "need". But neither's realistic anytime soon.

[@CityNerd]

Yes, these are super difficult questions -- I'll dive into it when I do a Pricing video!

[@bikemmm6167]

Please do more math related planing videos, thanks.

[@gvi341984]

Self driving is solving this issue with controlled speeds.

[@DanielinLaTuna]

You’re too young to know about domino theory! It was widely used during the Vietnam conflict (some would say war), predicting how global communism would progress, felling one democracy at a time. Seriously, a well designed presentation with accessible graphics. Thanks for sharing

[@MrTNHale]

Superb video. Congestion pricing works if it’s implemented in a progressive way that doesn’t hit people who can least afford it. If there’s a reliable transit option and people are choosing to pay to drive, all for it.

[@CityNerd]

Those are all the difficult parts! Will definitely explore more in a future vid.

[@GeorgeMonet]

But the people who are mostly likely to drive can more than afford the congestion pricing and would rather continue to pay for the luxury of retaining the use of their vehicle while the people who are poorer are more likely to use public transportation anyways. SO it isn't going to make any large difference outside of extra tax revenue.

[@veteranvlogger_swarnajit]

Statistically clear.

[@Dovietail]

Please put something taller in that niche behind you. That little bitty low thing in that great big lovely space is bugging the heck outta me.

[@joostvandergun5518]

I'm curious how much of the exponentially comes from the dumb approach to traffic management. If the time for green light is adjusted to the amount of cars. Is the exponentially then reduced?

[@CityNerd]

Yes, for this very specific situation, having a signal controller that can do early greens or green extensions (and programming that into the signal plan) for PM peak would help alleviate the delay...unless the other movements at the intersection are prioritized, worse, etc.

[@TristanMorrow]

:-/ how can you get people to drive faster and couple that with shorter cycle times?

[@CityNerd]

Theoretically, with connected/autonomous vehicles, you could improve throughput (saturation flow rate) on that left turn.

[@stiffjalopy4189]

I mean, yeah the city engineer WOULD be getting calls about that congestion, if only Urbanist KZbin would tell ppl who she is and what her number is.

[@buddy1155]

I have no idea what you are talking about, I am always first in line at every traffic light cycle.... but I do drive a motorcycle.

[@CityNerd]

Nice

[@emma70707]

English CCs are in Spanish fyi.

[@zachz96]

What about left turning bikes?

[@CityNerd]

Copenhagen left / protected intersection

[@MeatFists]

You better believe I went frame-by-frame for that "General Vegitativeness" flash. It was like catching a frame of nudity on TV in 1992. Totally worth it.

[@CityNerd]

Easter egg for the real ones

[@TerraqueousDragon]

Now I'm curious how a similar analysis for a roundabout intersection plays out.

[@eriklakeland3857]

I’d be interested in a video on Carmel, IN which is a suburb of Indianapolis that is known for its roundabout obsession. Ironically, it is home to the nation’s first stoplight.

[@seannajera1265]

Great idea. Would love to see that

[@CityNerd]

Carmel, IN is super interesting. Check out Bend, OR too! Roundabout analysis is a lot different, but it tends to break down later for a lot of movements. Tradeoffs with amount of land consumed and bike/ped integration, too, of course.

[@lostwizard]

Roundabouts are interesting when considering their failure modes. Roundabout evangelists often insist that roundabouts are the solution to everything, but there are cases where they fail hard, particularly in asymmetric traffic volume scenarios. If a roundabout has signals, it has probably reached failure point, at least during some portion of the day. An analysis of the situation would certainly be interesting. Also compared with an all way stop, which seem to be everywhere in my neck of the world. (No, all way stops are not the solution to everything, either. They're used around here in many cases where a roundabout would be better.)

[@pwhnckexstflajizdryvombqug9042]

Roundabouts are worse; when they fail they fail hard.

[@LoneGunman90]

Would love to see a video detailing “smart” traffic lights in the US. The one for my street seems incredibly dumb, like it is only programmed to ever save time on the busier cross street rather than consider the actual traffic conditions at the time.

[@hunterhurley5245]

My street is the exact same way. I've seen it red for me while green for an endless stream of nothing even though it is "smart"

[@codex4046]

@Zaydan Naufal is it that much more expensive? If traffic flows better there is less stress from it, people will be less tempted to drive through a red light, and people have more time to spend wherever they are going. If the costs of a smart traffic light are higher than the returns from it I would wonder if a traffic light is the smartest thing to have in that place.

[@CityNerd]

Yeah, my theoretical traffic signal here is slightly dumb -- you would hope that there would be an algorithm behind it that occasionally allocates additional time (recovery time) to over-capacity movements.

[@codex4046]

@Zaydan Naufal cctv and speakers? that's not expensive at all

[@saxmanb777]

Road Guy Rob does an excellent video on traffic lights and their sensors and cameras.

[@cardenasr.2898]

When I was a kid in the 90s my central Mexico hometown started building more road infrastructure like overpasses and interchanges, when the city was about 500K inhabitants. My relatives joked that all those new bridges were excessive for our "small" city. Now, 25 years later, the city is over 1M inhabitants, lots and lots of viaducts and underpasses have been built, most of them on the access roads to the city and the ring roads, however when a new underpass is under construction it always gets messy. Public transport was and still is lackluster, so even working class people bought cars to move around. It has just gotten worse. I recall my childhood years of empty roads, they're gone. I don't know if the civil engineers are in bed with the local government or the fact we have the largest Nissan plant on Latin America has fed the car culture.

[@fszocelotl]

I happened to go visit Aguascalientes twice in 2007 -8. I liked the idea of the city rings, but even then, traffic congestion was almost the same as here in Mexico City. I blamed then the climate, since there was in the raining season and wrre a couple of stoms that made a real mess in downtown... Three blocks walking along a flooded road to cross it to walk back to downtown Steren...

[@Jacksparrow4986]

That's the story pretty much everywhere: build roads and there will be cars and traffic and chaos. Build active/public transport, and people will move quietly and efficiently.

[@ShubhamMishrabro]

Whichever country America has a influence it is more car centric except countries who still build public transport

[@nadie8093]

Queretaro?

[@marchomotion]

I would love to hear more about congestion pricing! I live in San Diego, and our grand transportation plan just lost its mileage tax provision because the city council cut it due to public opinion/messaging. Now the city's big goals on many things--including multi-modal transportation upgrades--are possibly not paid for in the long run... developing story!

[@CityNerd]

Congestion pricing is so massively politically fraught. I'll definitely make a video soon, but I just have to figure out what angle to take on it.

[@NickCombs]

I'm no expert but it seems like tolls and the like mostly serve the wealthy. Any additional pricing on drivers is going to push more people into poverty, which is already at crisis levels. Maybe use it to help push middle class folks to bike & rail networks once you've made those viable choices, but at that point it's probably not necessary.

[@johnathin0061892]

@@NickCombs Exactly. These kinds of schemes are regressive and hurt the poor the most. The well off don't care about having to pay more to drive to work (or more for gas in the form of a "carbon tax") but it can be a severe burden on those on the margins who just want to go to work.

[@bikeny]

@@CityNerd Here in New York City, the CP plan hasn't yet been developed, but I suspect that nobody trusts that whatever money is raised via the fee will go to where it is supposed to go and also that whatever money does get to its destination, it will be spent inefficiently. I await your video on CP. BTW, you've gotten another sub as a result of this video.

[@koenven7012]

@@NickCombs That is why you have to make sure that there are good and reliable alternatives (mass transit for instance) before you do this, which is why this can't be a measure on its own, but has to be part of a larger plan. And also the price doesn't have be massive. See what Stockholm did for instance. I don't know the exact numbers, but the price was not high and it had a massive effect.

[@Bongo1020]

I really appreciated the graphic representation, helps explain something that would otherwise be quite abstract

[@CityNerd]

I didn't think I could do this adequately without some decent visuals. Thanks for the appreciation.

[@ionicoatmeal8578]

Interested to see if this compounding effect is apparent for freeway lane closures, and the effect that more lanes of traffic get better or worse with the same number of lanes closed

[@rokksula4082]

Interestingly the opposite was observed during the viadoom “carmageddon” in Seattle when the closed the viaduct but wouldn’t open the tunnel for another 3 weeks. The city added a bunch of transit options, including more water taxis, encourage people to work from home etc. and it worked. Traffic did not increase significantly during the closure. Ironically the missing carmageddon following the viadoom was used to demonstrate that Seattle doesn’t really need a waterfront highway. You can literally close a major highway and enact policies which eliminates the traffic. Sadly policy makers have yet to learn from this in Seattle. The tunnel is now open and they are in the process of building a major arterial road above it (see also West Seattle bridge fiasco).

[@PSNDonutDude]

It does. It's also the reason some freeways use signalized entrances to slow the introduction of cars to the freeway. By stopping just a few cars you can make the congestion go away.

[@CityNerd]

Analysis of "interrupted flow" (signals, stop signs) facilities and "uninterrupted flow" (freeways) facilities is completely different -- different enough that they warrant totally separate volumes of the Highway Capacity Manual! I may do another version of this video in the future looking at freeways instead.

[@rokksula4082]

@@CityNerd Here is a video idea: “Top 10 carmageddons that never were”, a list of high profile highway closures which predicted a bunch of extra traffic, bu only a fraction of-if any-increased congestion was realized.

[@dirkkarmel5209]

As a delivery driver: I can assure same teaffic congestion for any temporary route changes. Avoiding the peak congestion times, Quickly reduces delivery times. Because of this: I refuse to do deliveries during peak times. ( 2 hours in a.m. AND 2 hours in p.m. )

[@AaAa-uo3cc]

This is a great explanation, but as a math/cs professor, I have a quibble: this shouldn't be described as exponential growth. The effect is clearly super-linear, but would be better described as quadratic (x^2) than exponential (2^x). The effect here is quadratic because each additional car ADDS time that grows with the number of cars; exponential growth would mean that each additional car MULTIPLIES the time by a constant factor, which would have a much, much bigger cumulative effect. In this context, either quadratic or exponential would be bad, but in other contexts (like disease spread) there's an enormous difference between these growth rates!

[@CityNerd]

I'm with you -- but that terminology doesn't scan on a video thumbnail!

[@Chris4942Chris]

Could you do a video talking about how citizens can help influence public policy in their own cities around issues such as this? Congestion pricing sounds like a great idea, but given how the recent attempt to implement a parking management systems (paid parking) in my own city was received by the population, it sounds like it would be a really hard sell. Not saying specifically to do a video talking about how to get congestion pricing implemented in a city, but how to advocate for positive change in regard to urban transportation. Maybe a top 10 examples of times urbanist advocacy groups made stuff happen in cities in North America and how they did it?

[@CityNerd]

Conventional advocacy is not my wheelhouse (my background is consulting), but I have massive respect for the people who are good at advocacy and navigating the political system -- and I know a few of them. Let me give this some thought.

[@pottingsoil]

This would actually be extremely helpful.

[@tubester4567]

Raising costs is only going to punish the poor, and create a road class system, like we have a housing class system. We already have enough toll roads. There are many other things to try first. Sure public transport is a good option for some people, but how about incentives for people to ride a motorbike or scooter?

[@shreyas9701]

@@tubester4567 my city tried to incorporate congestion pricing too but it immediately got labeled as a money grab by the government and it hasn't gone through. I would agree that it will def hurt the poor more. Subsidizing their cost based on their income might help but then things get complicated and you have more paperwork and forms to keep track of as a citizen. My other question is how else can we fund public transportation or other modes of trransportation? Any move on trying to collect money for the betterment of the whole community leaves people angry. Americans hate getting taxed. So what's the solution?

[@billyswong]

@@shreyas9701 I am not an American nor living in America. After watching all these videos, my understanding is, you guys shall fix the city planning and zoning first. Before single family houses reduce to a certain percentage (which may never happen as it is a cultural issue), the immediate traffic fix is NOT congestion pricing. The band-aid is encouraging e-bikes and e-scooters for rush hour job home travel. They are fast enough to ride on the motorway and they are far smaller in size so the same road can pack a lot more of them. Then the next step may be to build railway lines that allow people to ride / bring their bikes / e-bikes / e-scooters onto the train and travel with them. Now the bikes and humans are more closely packed and move even more efficiently.

[@elefante8572]

Really enjoyed the video, getting into the math is really interesting and I think you could even cover more advanced or complicated math. The graphics were really helpful, how do you make them? I would love to see a video exploring congestion pricing along with induced demand, and the effect (or lack thereof) of transportation alternatives on congestion!

[@CityNerd]

I'll definitely do a video that goes deeper on congestion pricing at some point.

[@warrenjones497]

Traffic congestion, like other issues related to city/community life, requires a unified, system based approach. Number of car trips is related to number of dwellings and to work/school/shopping locations and is closely linked with income. (not everyone can afford to own a car) Part of our challenge is that all these factors are viewed/managed by separate agencies/interest groups. Lack of unity is an overall limiting factor as regards mitigation of problems or improvement of the quality of life.

[@kevinlove4356]

The number of car trips is also related to where people live in a city. For example, those who live in the downtown car-free zone are unlikely to own a car.

[@dirkkarmel5209]

@@kevinlove4356 Wish this were true. Desire for route, Increases directly compared to number of people involved. Regardless of where, these numbers follow similar patterns. -- Have you ever tried to park, downtown ? Obtain twor forms of grid-lock ! -- Numbers of vehicles, -- Numbers of people wishing to use the mass transit system.

[@omarmunoz4409]

It would be amazing to see you tackle all this issues with Cities Skylines. It would be so interesting to watch you build your own city, with public transport, traffic and motorways. You should try it!

[@CityNerd]

Oh man, I'm a recovering gamer. Don't make me backslide!

[@jrm371]

You can balance it out. Doesn’t have to consume your life lol

[@AdamBerkan]

I used to take an exit in Mountain View (101 N to Shoreline N) that would back up at the light from 8 am to 11 am, and let through ~30 cars a cycle. I once (while siting in the traffic) figured out that every car that decided to use the exit caused a car after them to miss a light at EVERY traffic cycle, which was about 2 minutes long. If a car showed up at 8:02, the next 90 cycles would each have one car shifted to the next cycle, and therefore be delayed by 2 minutes. That works out to 180 minutes of delay PER CAR!!! Congestion is non-intuitive... I usually showed up around 10:30, so I was only delaying a few cycles after me, but this realization strongly encouraged me to take my bike.

[@Jakob_DK]

Excellent point and explanation.

[@CityNerd]

It's amazing and crazy that this is the actual transportation system we rely on, when you really think about it.

[@doktarr]

I'd love to see a video on how to make congestion pricing work on surface streets.

[@aquaticko]

I think that's the thing that really gets me about autocentric transportation planning. The only thing that makes it viable is a roughly static number of drivers driving a roughly static distance, and socioeconomically speaking, the justification for pouring all the resources into that type of transportation development is essentially that the economy will always be growing and more people will always be driving more.

[@GeorgeMonet]

No. The justification is that people are traveling to work by car of their own choice. Usually from a distance several towns over or longer.

[@aquaticko]

@@GeorgeMonet You're assuming that people are living so far away from their work by choice. Restrictive zoning laws--both against higher-density residential and mixed-use zones--means there's no reason to assume that's true.

[@jandraelune1]

Need to give more transit options (buses, bike infrastructure, trains, walkability) than a personal car and make the personal car actually mean ' freedom and independance ' instead fo ' reliance and dependance '. Remove ' stroads ', the worst thing you can have in a city or town.

[@tylerradtke4110]

Don’t mind me just paying respect to the algorithm

[@thelegotechnicchannel1256]

Actually this stuff should be told at school

[@CityNerd]

The algorithm demands offerings. You have pleased it.

[@AaronSmith-sx4ez]

Good video...but I actually think a better way to illustrate exponential congestion is with on/off ramps as opposed to traffic lights. The problem with a freeway is there is a finite space-time window to enter/exit a freeway via the far right or far left ramp. So a 10 lane freeway doesn't have 5x the capacity of a 2 lane freeway, because the cars can't use the lanes equally. Each lane change creates slowdowns for traffic behind you, and many vehicles have to stay close to the exit lane to get off...which in turn bottlenecks the cars trying to get on. On top of this roads take up a lot of space which results in lower density development and forces longer commutes. A final thought experiment to prove my point...would a 100 lane freeway still suffer traffic jams? I would argue yes, because the ramps and not the lanes are the bottlenecks most often. I actually think a 100 lane freeway would be a good video topic to prove many concepts.

[@dirkkarmel5209]

-- Might wish to start with: Autobaun (sp??) In Europe.. ?? Where are it's greatest problems ?

[@mdhazeldine]

I live in London (UK) and the congestion charge definitely helped matters but I don't think it's gone far enough. Congestion is still terrible, despite having a great commuter rail system and the Tube, I still see a lot of single occupancy vehicles driving into the city every day. I think the zone needs to be enlarged and charges increased further. I say this as a driver. I drive into the city (occasionally) for work because I have to (I carry a lot of gear in my car, which I couldn't take on the train or bike), but I see many people who really don't look like they need to be in a car. If the charge was higher, a lot of those would go and things would get better for everyone else who have to use the roads.

[@CityNerd]

I don't know if I'm up to date on the London cordon zone. Has it expanded or contracted recently? Any recent studies on pricing/volume? I think the pricing structure and geography need to be revisited regularly to keep it useful and equitable.

[@mdhazeldine]

@@CityNerd There was a western extension that was removed about a year after after its introduction. I think it should probably come back. Recently there was a new Ultra Low Emission Zone (ULEZ) introduced (a toll on gas guzzling vehicles) but my anecdotal experience so far is its made no difference. Perhaps time and official data will tell the full story.

[@shreyas9701]

I'm curious about the impact on lower income individuals who can't pay the extra fee? My city tried to implement this but it got shut down immediately and was labeled as a cash grab by the government. I should mention I live in America and all Americans hate taxation. But without some sort of tax how can we even start funding for better public transportation or infrastructure for bicicyle lanes etc? Not to mention how car centric and difficult it is to go anywhere without a car. So it's not fair to force people to not use cars when we don't have good alternate modes of transportation but we can't get alternate modes of transportation without a tax. It's like the Catch 22. sigh...

[@mdhazeldine]

@@shreyas9701 Yeah, the U.S. is a bit screwed in that sense. Over here, if you can't afford it, you just walk, bike or take the train. I think probably the key in the U.S. will be to densify development in certain areas, with mixed use zones and develop walking and biking (and eventually transit) around those areas, and make sure that's where the affordable housing is located.

[@shreyas9701]

@@mdhazeldine right- it sounds impossible to try to get any mixed use urban planning done. Everyone loves their car and single family homes too much 😭 I might just move to a different country. Nothing is gonna change in America anytime soon.

[@r.d.9399]

Congestion pricing is pretty much a tax on the poor just like pay per mile and tolls are. You lost me there.

[@CityNerd]

Depends how you implement it.

[@jus4795]

Not if public transport is reliable.

[@ianmcgregor8152]

Can you do a video comparing Level of Service and Vehicle Miles Traveled? I've heard that they can be used in place of one another when looking at road projects or proposed developments in an area. It seems to me that each metric measures something very different.

[@CityNerd]

They are very different. State of California is the leader, I believe, in moving transportation impact studies from a LOS focus to a VMT focus. I'll add it to my topic list!

[@fattypikachu1495]

One other thing that can compound the aforementioned inefficiencies is bad weather/road conditions (especially when you're like me and driving in Canadian winters) Since cars take longer to accelerate and have to be slower in general on ice, road capacity can be temporarily reduced and cause the same exponential traffic jams. It can pretty easily turn an otherwise normal intersection into waiting 20+ minutes for a left turn...

[@CityNerd]

Great point.

[@moritzm.3671]

Loved the video. I personally have to say I do enjoy these kind of videos more than the top 10s (which are still very interesting) and I really would be delighted to see more theoretical videos in the future. One completely unrelated thing, I was wondering if you could maybe do a video on the public transport system in Karlsruhe (Germany). I find that an very interesting one because 1. The city isnt really big, and it's always interesting to see smaller citys develop public transport systems. 2. It is an early adopter in multy system trains with trains running on the normal tram Tracks and the Deutsche Bahn Tracks even running on the same tracks as the ICE (high speed rail) 3. They just finished a huge infrastructure projects with an downtown city Tunnel which replaces trains running through the pedestrian zone. 4. The network is huge for a city that size with trains running from the city centre to quit remote places in the mountains (Freudenstadt is 80km away) 5. The system grew extremely nicely by using existing tracks which where underused and is completely electrified 6. It kind of shows that quite good service can be given to very remote region's I don't know if you would be interested in this system, but I always found it very interesting especially as an model for city's which may be interested in improving there systems cheaply.

[@CityNerd]

I definitely want to do videos that explore German transportation systems and ideas. Lots to learn from there!

[@moritzm.3671]

@@CityNerd Btw. If you need help with translations, feel free to ask.

[@hypairoi8792]

Wow! What a great video. Keep it up man!

[@twylanaythias]

Been driving for 40+ years, professionally for 13+ of those years, and I would argue that 60%-80% of traffic problems (particularly on freeways) are due to a small percentage of 'oddballs' - people who don't (usually won't) conform to surrounding traffic. While they're halfway tolerable when congestion is minimal, a single oddball can potentially shut down an entire freeway if traffic is at least half of the design capacity. The first mantra of professional drivers is "go with the flow". It's almost hilarious when some looney flies past me going ±15 MPH faster than the rest of traffic, weaving between lanes (usually without a single turn signal), only for me to pull up alongside them at the next traffic light. The same happens in the opposite direction when someone insists on driving slower than the rest of traffic, particularly when they do so anywhere other than the rightmost lane. Even then, it doesn't take long before other drivers become more prone to take undue risks in order to switch lanes and get around the oddball. When traffic is light, the impact of either extreme is negligible - there are plenty of opportunities to change lanes at minimal risk. But as soon as congestion begins to build, changing lanes (especially if going a different speed than prevailing traffic) becomes exponentially more dangerous. Furthermore, drivers who are overtaken at speed have a tendency to panic and reflexively hit their brakes; seeing brake lights ahead, the next driver hits their brakes (likely harder than the person ahead of them had), etc. You very quickly have people slamming to a complete stop in the middle of the freeway for no reason whatsoever. Which means that someone is likely to switch lanes suddenly, bringing adjacent lanes to a screeching halt as well, expanding to include the entire roadway - sometime even ensnaring oncoming traffic in the process. And all because ONE driver insisted on going 10 MPH slower than everyone else on the freeway.

[@veteranvlogger_swarnajit]

Well expressed the facts behind. Nice Video. I liked. Subscribed to your channel.

[@hunterhurley5245]

Great video, very informative. I'd love to see your take on how best to implement congestion pricing and where/when it would be necessary.

[@turf6863]

Damn, it goes _exponential_?! Not polynomial? Is this the reason why my intersections in Cities: Skylines slows much more when there were slightly more trucks in the road?

[@badhorse84]

I work as Vertical transportation consultant (read elevator guy) and I can relate to this 100%

[@CityNerd]

OOOhhhhhh, elevators are such a good analogy. Corporate office building elevators at the lunch hour!

[@adamborchert5965]

Exceptional video! One thing to also keep in mind for perspective on the inefficiency of cars is that each cycle in this example there are ~7 people moving through the intersection.

[@CityNerd]

Most likely -- unless it's on a bus route!

[@steveszigethy]

Thank you for normalizing that it's OK to be an advocate for active transportation and transit while also thinking that congestion is bad.

[@kevinlove4356]

Transit and cycling are the way to eliminate congestion. Look at what is happening in Paris, France.

[@CityNerd]

That's my new channel catchphrase: "Normalize Normalcy"

[@LucarioBoricua]

This is one of the factors, but a really significant one. Other factors contributing to exponential growth of traffic also include these: - Land use: as cities sprawl more and more, the average trip length grows. Each trip then contributes to congestion along more portions of the road network. Suppose you have an arterial with signalized intersections every kilometer. Someone living in the inner suburbs 5km away would likely affect up to 5 intersections; but someone living in outer suburbs 10km away would affect up to 10 intersections, if they're heading to the same city center. All of the congestion-causing phenomena effects mentioned in this video manifest at more places, generating gridlock. - Induced traffic demand: believe it or not, people have a surprisingly high tolerance and flexibility for congestion. If a major route has its capacity increased through geometrics (ex. more through lanes, more turning lanes at intersections, grade separations) this reduces travel time in the short-term. The effect of this is people who were using strategies to avoid congestion (alternate routes, alternate trip times, carpooling, alternate destinations, trip avoidance transit as a back-up option when they'd rather drive) will pour into the main route, and them vacating the alternate route attracts more trips elsewhere. In the long-term, the expanded capacity makes long-distance trips more attractive, encouraging sprawl. - Traffic incidents: situations which obstruct traffic can have an outsize effect on congestion, such as car crashes, disabled vehicles on the roadside (or sometimes in the lane if there's not enough shoulder/berm space available), inclement weather and so on, will create localized disruptions to the traffic network. Add up enough of these, or do just one of them on a busy route, and this will propagate congestion big time. There's also a risk of secondary traffic incidents caused by the initial incidents, which may mean the first incident's effects alone can create a prolonged disruption.

[@CityNerd]

All great points. Thanks!

[@AdamMansbridge]

Peak time based congestion pricing is all good. Poor people and misers can drive before or after peak, and eventually take public transport. Oddly my city charges more for peak time bus usage, but I think they'd rather see higher peak bus usage and lower peak car usage

[@rileynicholson2322]

The problem with congestion pricing is that, in the absence of viable alternatives to driving, it amounts to a regressive tax that affects poor drivers in an extremely negative way while benefiting the rich, making it hugely unpopular. Without a robust plan to correct this, any congestion pricing plan is probably dead on arrival.

[@CityNerd]

Well said.

[@paulblichmann2791]

Why should poors be entitled to drive.

[@Theincredibledrummer]

As usual, a great video. If only we had more planners and engineers in the system that grasp how transport works like you do

[@stevengordon3271]

I truly believe that most of them do grasp these problems, but their hands are tied.

[@CityNerd]

@@stevengordon3271 I think that's accurate. Or, they know, but it is just so, so , so much easier to just do the same thing you did last year, or ten years ago.

[@FrontierBill]

@@stevengordon3271 most of us (engineers) do understand the problem. But getting clients (cities/counties) to buy in is tough. They come to us with a single congested road, and want it to handle more traffic. They'll hire another firm for the job if our proposal is to invest in bus route and bike lane expansions.

[@stevengordon3271]

@@FrontierBill In other words, "your hands are tied".

[@FrontierBill]

@@stevengordon3271 in an oversimplification, yes. I wanted to get across that, in general, the project isn't as vague as "improve traffic". By the time it gets to a transportation design consultant, the client has defined the project more narrowly as "come up with ways to add a lane to improve traffic throughout". The most leeway we get is in how we arrange lanes or handle parking. Coming back to the city with a recommendation to improve transit to reduce traffic demand is not addressing their actual project. Now the place where we can make these recommendations is if you get a contract for something like a city masterplan. In that, you can push for investment in transit to mitigate future traffic congestion.

[@BoredSquirell]

Not so sure about congestion pricing, but parking pricing - definetely yes. The ideal situation is where you have a car at home (if you want to own one), but the parking at your destination is expensive enough so that you don't actually use it. Now you might ask why own a car if you wont use it. My experience tells me that public transport is almost impossible in rural areas, forests, minor intercity routes, etc. And I do road trips a lot. At least one kind of lifestyle requres a car even if not using it in the city for everyday transport.

[@CityNerd]

Yeah, to me "congestion pricing" is an umbrella term that includes a lot of potential strategies, cordons, tolling, VMT pricing, and definitely parking. I'll discuss more in a future vid.

[@raycambridge8950]

Thanks for the great explanation. You've probably also explained why you shouldn't flush paper towels down the loo, amongst many other things... Also, feel free to venture beyond North America.

[@simoneh4732]

Excellent! This is a great micro analysis on how cars on the road effect one intersection. I wonder what kind of study there has been on the macro level of congestion. When each car causes exponential growth of delays, the whole system is going to be strongly effected by the average trip distance. Does 1/2 the number of cars traveling twice the distance cause the same amount of congestion? This has huge implications for suburban growth and development patterns.

[@sybrandwoudstra9236]

Long story short: yes. Cara travelling through lots of intersections will use the capacity of these intersections. Shortening trip length world indeed reduce congedtion. Source: I am not a professional, I just play cities skylines.