The only difference here that I think is really meaningful is that bike lanes generally aren't already fully built out and at full capacity.
If we didn't believe bike lanes would induce demand for biking we wouldn't say "let's get people out of cars" as one of our major reasons for adding bike lanes. We accept - even hope! - from the start that more bike lanes will cause more biking. It has upsides compared to car commuting.
But because we don't have an already saturated, congested network of bike lanes, we aren't going to be hitting the limits of "why didn't adding more parallel bike lanes reduce the amount of congestion?" - the congestion just doesn't exist, and we'd have to have a LOT more biking to make it exist. And if we get to that point, it's a big win! Fears of future bike traffic should not stop us from building bike lanes.
Everything else about why "they're different" seems like handwaving.
A key analogy that went unused in the article is the Red Queen's Race: "it takes all the running you can do to stay in the same place" applies to car traffic precisely because cars are large and powerful and are persistently required to make slow turns and smooth stops relative to their size - think of all the roads where you have to carefully inch out, keep deliberate pace and stopping distance, and so on. Spaces that are "for cars" correlate to spaces that are unsafe "for people". If you add more than a small topping of car traffic to a road, they will impede each other. Therefore, to make large numbers of cars move quickly you have to add disproportionate amounts of car infrastructure, which creates car-centric land use patterns, which inhibits alternatives and makes cars the default by dint of being the smallest unit that can safely use a road. "If they get bigger, I must get bigger too" is applicable thinking for someone who wants to feel safe on the roads.
If you reduce the scale, the speed, the headways, you have greater ability to adjust. While car pileups are expected, bicycle pileups are a thing usually only seen in races when the limits are being pushed. Ordinary bike commuters can navigate safely without rules when given a mixed bike/pedestrian space of sufficient size. Bikes don't get bigger to feel safer. The resulting infrastructure scales better for the cost, and the Red Queen's Race is averted. When bike lanes reach capacity, the failure mode is crowded-stadium, not stand-still freeway. Traffic slows down gradually instead of creating roadside bloodbaths.
Transit does experience more of a headache from induced demand pressure since it also uses large vehicles, and the entire trip experience is contingent on not holding up that one train or bus - while Tokyo's system works, the crowding is notorious, and the train stations have sizable footprints. But as a collective effort, it can also be much more coordinated and deliver useful results from capacity increases.
UC Davis alumnus here. Bike lanes at full capacity work much better than motor vehicle lanes at full capacity. You may have to wait to join the traffic, but since you need a smaller space there’s less wait time. Roundabouts are very efficient. Accidents do happen, but are far, far less deadly and can almost always be cleared in under two minutes.
Just watch out for freshmen at the first rainstorm. You can tell them apart by their freshman stripe — the result of not having a rear fender.
The point of the article is that bikes, by virtue of their limited speed, don't suffer the feedback loop of less density that cars do. The distance you can travel by bike in half an hour is not influenced that much by infrastructure.
There are two other reasons bike lanes don't have the kind of demand induction properties that roads do:
-Bike lanes (and ultimately, bike destinations) have way higher humans-per-square-foot of road / parking lot density than cars lanes. The throttling mechanism on behavior for the car example is ultimately drive time, and new lanes quickly become capacity constrained (first at the interchanges; later at the parking; last in the lanes themselves) in a way that slows ultimate travel back to the indifference equilibrium. The equivalent for bikes tolerates a way higher flow of humans.
-Induced demand for cars is in part a function of the fact that you can (up to a point) drive at any speed, meaning that if roads are added that support commuting in from 30, 40, 60 miles away, that can be a doable commute. There is no amount of development that will create a 60 mile bicycle commute. Here, the demand induction mechanism with travel lanes and housing is reversed: you need convenient housing to drive the demand for bike lanes.
The Embankment in London (Westminster to Blackfriars) lost one of its four vehicle lanes for a kerb separated two way cycle lane. It carries more traffic than the four vehicle lanes, but looks far emptier, which invited much complaint at first. I’m glad to see TfL are still building more cycle lanes, various types to suit the roads used.
It is surely true for the density part. However I have now seen bike lanes that are two years old that would be efficiently « unjammed » by doubling.
Another great aspect of bike density is that when you double the lane you allow way more traffic. When you are slow and small, you don’t need much space to overtake a slow electric bike.
The reason bike lanes do not have demand induction effects is because there is inherently low demand. A majority of the population cannot use bicycles for long trips, and even those who can cannot use them for all trips.
Bike lanes are ableist and classist. Only healthy citizens with an excess of time and energy are able to use them for trips. The elderly, children, those with heart conditions, asthma, or many other health conditions, and anyone needing to transport anything heavier than their own body cannot use the lane. In most cities this represents a minority of the population. Creating exclusionary space for bicycles is the opposite of progressive policy and efficient urban design.
4 years ago, few bike lanes and very few bikes. Detractors of the newly created ones were arguing about the ressource waste.
Today it is one continuous line at rush hour and some lanes are completely jammed.
I am not an expert, but what a change. The pandemic may have helped but it is a true transformation. Many people who would have never bike in Paris a few months ago now bike daily to commute.
It certainly took more than just laying lanes, planning and choosing the right places to create lanes has certainly a lot to do with it. But once the main places were connected by safe lanes, it began and never stopped.
Millenia-old super dense city certainly helps too, nonetheless many thought it would be impossible.
Would probably be harder in a less crowded place.
> In 1941, your kid might have walked 15 minutes to the neighborhood school. In 2021, you drive your kid 15 minutes to school. Oh, and this isn't your choice: they tore down the old school and replaced it with a parking lot.
> In 1961, you might have biked or driven a few blocks to a corner store for milk and eggs. In 2021, you drive 3 miles to Kroger for milk and eggs, and there is no corner store. Has your utility increased? Or are you mostly just consuming more resources?
I would argue that utility _has_ increased; It's just that the market has re-organized itself such that the increased utility comes in the form of more flexible locations for houses and businesses rather than in the form of decreased commute times. One grocery store every 5 miles costs far less to maintain than 100 corner stores distributed evenly throughout the city, and you can get more house per dollar buying a house in the suburbs rather than if everyone were competing to buy housing smack-dab in the middle of a city.
I think perhaps a stronger version of the author's argument would be to point out that road use is an externality. Building more efficient roads comes at a significant cost, but road users don't pay that cost in a manner proportional to their use of those roads. Therefore the market does not factor in road construction costs when deciding how to organize cities, only costs of the transportation itself like commute times and gas usage.
I dislike the term "induced demand" for the same reason the author gave. "Induced demand" is really just "demand"; all economic systems work that way. The only thing different about roads is that our current system of road construction funded primarily by income taxes makes road use an externality.
> One grocery store every 5 miles costs far less to maintain than 100 corner stores distributed evenly throughout the city.
I'm not at all convinced that this is true. It would make sense in a vacuum, but there are a lot of negatives from the road infrastructure necessary for large driving-only grocery stores.
Dense cities have lots of smaller grocery stores rather than a few large ones. I'm sure there's a reason for that.
A grocery store every 5 mile costs a ton of fuel to maintain as clients need to drive in. It requires much more roads to be built and bigger ones too. It's not clear at all that it's more efficient when considering the whole picture
Induced demand is literally just latent demand that wasn't met and latent demand that wasn't met is just demand.
The only difference is the appearance that the demand is truly endless. Building roads is a subsidy to cars. People don't pay for the roads they get for free. The optimal strategy becomes driving because public transport is "inconvenient" because the alternative to bad public transport isn't better public transport, it's more cars. So, now the entire city wants to drive. Of course, the problem with that is that cars are such an inefficient means of transport that it's impossible for everyone to drive. The fairy tale of induced demand is born.
I would love to be able to bike to work. But I can't, even if there were bike lanes. I live in an American suburb, which by design is located far from industrial areas, where jobs are. Too far to bike. There are a few high-density residential buildings in the CBD, but they are only affordable for millionaires. The public transportation here is for show.
Two years ago, the highway nearby completed a 5-year widening project. During that time, traffic was so bad I had to check Google Maps every day to find out which route I should use. Now that the project is complete, I never check Google Maps anymore. I just use the highway without even bothering, as the cost to drive on it is now clearly the cheapest. My life is better in the short term, but eventually more homes will be built, traffic will increase, at some point I'll have to go back to checking Google Maps every day, and they'll start another road-widening project.
I've lived here long enough to experience this cycle first-hand, and nothing has changed logically that would stop this loop from executing again and again. At some point, I'm sure a physical limit will be reached. Either we run out of space, or run out of money, or something else.
Electric bikes really change the "too far to bike" equation. Depending on your fitness level and the route, you could easily ride 10 miles (or more) and arrive with minimal sweat.
As a cyclist, I believe that bike lanes do induce demand, but there are some important differences.
A single road can attract travels which begin or end far away from the road. So its effect is felt on a larger territory and further away. A road needs only few exits to be connected to other roads.
Bike lanes are more like capillary network than arteries. A single bike lane is almost useless, because it can serve only travels which begin and end in a narrow strip around the lane (maybe a block away). Two bike lanes which are not connected will be used much less than two connected lanes. Even a single discontinuity of the network can make bike travel unfeasible.
So rather than talking about lanes, we should talk about lane networks and their density. And up until certain density the network won't be used much. Only after reaching that threshold we can talk about effects it may have on city development. Similarly, a car road will not generate induced demand nor attract much traffic if it is missing a bridge across the river.
Let say a bike lane attracts traffic if the starting point and the destination are within w/2 from the lane. Let's assume uniform distribution of potential starting and destination points. Then in a city area A, a bike lane of length L will attract only Lw/A potential commutes (within a strip around the lane). There are two important observations to be made: 1) the induced demand is proportional to the length of the network L, 2) parameter w is probably small, likely ~ 200m, so 1 km of a bike lane will have a smaller and more local effect than 1 km of the road. To cover 1 km² of urban area, the well connected network would have to be a grid with the total density of bike lanes ~ 10 km / km².
While I believe the logic in the article is sound, I think it missed the mark on what actually transforms cities in such a way.
It's not the cars - they're just tools. It's the insatiable appetite for living space.
There's a trend in the city I grew up in(Warsaw, Poland) that started over 20 years ago and continues to this day - people grew tired of living in crammed, Plattenbau apartments, so they moved to smaller towns(in part inspired by their notion of how Americans live) adjacent to big cities where all the jobs were. Additionally at that time interest rates were so high that this was an option for those who couldn't get a mortgage for an apartment.
Cars followed, but not everywhere. Places close to railways were an exception, but only up to a point, because over time commuters exhausted any spare capacity there was, so the remainder had to drive and bear the not insignificant costs of that. In the meantime a highway was built, but that didn't help for long.
Was Warsaw hollowed-out by this? Hardly. What happened instead is that it started cannibalizing smaller (but still relatively large) cities.
I utterly despise the “induced demand” conversation.
Will building more lanes “solve” congestion? No! Will building more lanes allow more people to get to more places? Yes!!!
Latency and throughout are two different metrics. Building more road does not necessarily reduce latency. However it does increase throughput. This means more people have more access to economic opportunity; and that’s a good thing.
I think that what will spur the use of bike lines is the surge in electric two-wheeled vehicles: e-bikes and e-scooters and such. Thanks, I suspect, to improved battery tech, those things are everywhere.
Bike lanes will not induce much demand if all you have is human-powered cycles. Maybe on sunny days, in flat areas.
Even as a cyclist, when I hear of new bike lane construction, my feelings on the matter are "meh" or even negative. I think we should instead just normalize cycling among the cars (mostly by educating drivers, who either get pissed or are too cautious to pass even when they have plenty of room). Bike lanes just create the mindset that bikes should be separate traffic, and screw you over as soon as you need to take a left (now you need to merge into the cars on your left instead of already being between them).
I rode my bike across the country and my favorite city for cycling is still Cleveland. Not a whole lot of bike lanes, but wide enough roads and flat terrain. And the only time I was ever struck by a vehicle was when I was riding in a bike lane (because they were trying to turn right).
I probably would have agreed with you until I spent a lot of time in the Netherlands. Imagine saying the same thing about pedestrians: “I think we should normalize walking among cars. Sidewalks just create the mindset that pedestrians should be separate traffic.” Yes, to do this right, you need more than just bike lanes down each street that end in normal intersections. You need intersections with separate signals for bikes and cars, with no right on red, with grade-separated crossings at major roads. The Netherlands has done this for nearly every road in the country, and no it wasn’t always thus - it was done starting in the 1960’s as the result of a massive grass-roots people’s movement.
I think that this cannot be solved by "educating drivers".
Physical separation is needed for lanes with radically different speeds. Today, sidewalks (4 kmph) are separated from cars (40+ kmph). Because of demand of people traveling around 20 kmph, we need another separated lane for bikes and other e-mobility crowd that is able to move approx. in range of 10-30 kmph. Because of safety new lane must be physically separated.
Also, there should be wise to set some speed limit for these lanes, like 30 kmph, for cases when lane is used by hi-powered e-mobility vehicles.
In theory, parts of town where car speed is so limited to speed of bikes (25 kmph?), separation in many cases disappear. Nobody wanna be driving in such speed anyway.
The “vehicular cyclist” is very rare. I tried it a handful of times and it felt like an unnecessary risk (ie, death or permanent disability). Way too many distracted or under the influence drivers on the road and all it takes is one to make a permanent life altering change.
US cities need to be built around bikes. There are known models that work (Amsterdam). There just needs to be a significant paradigm shift in American mindsets and dependency on vehicles.
I sort of felt the same way.
But our city’s recently been building segregated lanes on the main central routes and it’s great to see little kids riding in them where before it’s was almost all folks in Lycra - point being it’s made cycling more accessible to people who can’t contend with full traffic.
I think this covers a lot of good points and I'm happy to see it, but the final section seems like a just-so. I've wondered if the difference in bike-induced-demand=good;cars=bad follows these lines:
- Roads/cars often leads to the phenomena of something like grid-lock. A network might be able to throughput 100 cars a minute when only <=100 cars are trying to get through, but try 101 and it starts dropping: If 120 cars attempt passage at once, congestion actually causes the throughput to drop to like 80 (think of those backward-propagating traffic-wave videos). If 150, throughput drops to 70 etc.
- You can add more roads/highways but if it doesn't address certain chokepoints, that throughput will still start descending at some point (though maybe a bit higher now like 110 cars/minute).
- Sometimes you can address the chokepoints, but after some expansion the remaining chokepoints are essentially having the buildings and city intersections themselves, at which point you can only address the bottleneck by rebuilding buildings further apart, which leads to a cycle of worsening pedestrian access, local-depopulation, and more cars.
- And then finally, maybe bikes are different in that they are small and agile with a congestion-failure-mode of being walked. It's hard or unlikely to get to a bike usage level that would lead you to want to move buildings very far apart to support them.
- Or maybe bikes are just simply so small that the preferred distance between buildings anyway (for sun light, privacy) can support most realistic biking numbers (which would be limited by density limits anyways: elevators only practically go so high, commuting biking trips can only be so far).
- Ultimately I wish there as a bit more explained here, maybe by someone that designs traffic/city simulations if that's how the best cost/benefits are tested now. It's really confusing that urban planning advocates concentrate on the un-improving car-trip-time/congestion KPIs like it's a dunk when it really seems some throughput-capacity utility metric would be more important.
Induced demand is really interesting, and most people aren't aware of it.
It applies to things like traffic, and yes, housing.
If building more housing lowered rents, I could finally afford a place in NYC, or LA, or SF. Unfortunately it doesn't work that way. But I wish it did.
I ran into the second effect in a study about traffic I glanced at in a library. It was slightly different, but the result was the same. It went like this:
1) more roads means less space for houses
2) this means people live farther away from where they need to go
3) this means they are more dependent on their cars
4) this means there is inevitably congestion and you need more roads
5) go to 1
Given that over a long enough timeline and in the aggregate humans are rational and humans also want to minimize commute times, it only makes sense that the average commute time across all substitutes converge.
Thus, if you wish to decrease your commute as a driver, the best possible strategy is to advocate for increased alternatives.
More interesting question (for me) in the context of cities: Do apartments induce demand similarly to roads? That is, does building more and more (and smaller and more expensive) apartments actually fuel the housing crisis in big cities?
Given the cost of housing in major cities, and the relatively lower cost in far away suburbs, doesn’t the argument about development patterns imply that building highways will help with cost of housing in the medium-long term?
yes, but the fixed and variable parameters to "use" and "density" are different.
And luckily, except for outside Amsterdam Centraal and a couple of other places, it doesn't matter: The fixed and variable parameters of the model are far above where we want to be and far above where we would be, if we reduced single occupancy car-type vehicle use.
If we include the crazy, semi-fatal Dutch microcar, I think we might get to the worst of both worlds: thousands of people old and young driving microcars like they are in Legoland on a toy road, but the road isn't toy.
My experience is anecdotal but I have observed that in Pittsburgh, the thing that was accomplished by adding bike lanes was to increase traffic congestion on roads that weren't ruined by the bike lanes.
"Europe’s super bike highways must have an impact on where people choose to live."
What I'm seeing in a city with growing bike infrastructure is the increased attractiveness of city homes which are "mid-distance" from jobs i.e. places which are too far to be walkable but within biking distance - if you have to use a car anyway, then you might as well go a bit further and get a suburban home instead, but biking augments public transportation in allowing a bit larger "dense city" instead of a lot larger suburban sprawl.
[+] [-] majormajor|4 years ago|reply
If we didn't believe bike lanes would induce demand for biking we wouldn't say "let's get people out of cars" as one of our major reasons for adding bike lanes. We accept - even hope! - from the start that more bike lanes will cause more biking. It has upsides compared to car commuting.
But because we don't have an already saturated, congested network of bike lanes, we aren't going to be hitting the limits of "why didn't adding more parallel bike lanes reduce the amount of congestion?" - the congestion just doesn't exist, and we'd have to have a LOT more biking to make it exist. And if we get to that point, it's a big win! Fears of future bike traffic should not stop us from building bike lanes.
Everything else about why "they're different" seems like handwaving.
[+] [-] dcposch|4 years ago|reply
Here's 60 people in cars, in a bus, on bikes:
https://lh3.ggpht.com/_9F9_RUESS2E/S7tbclwxiPI/AAAAAAAACmw/u...
To quote ru paul... "you're not stuck in traffic. you are traffic."
[+] [-] megameter|4 years ago|reply
If you reduce the scale, the speed, the headways, you have greater ability to adjust. While car pileups are expected, bicycle pileups are a thing usually only seen in races when the limits are being pushed. Ordinary bike commuters can navigate safely without rules when given a mixed bike/pedestrian space of sufficient size. Bikes don't get bigger to feel safer. The resulting infrastructure scales better for the cost, and the Red Queen's Race is averted. When bike lanes reach capacity, the failure mode is crowded-stadium, not stand-still freeway. Traffic slows down gradually instead of creating roadside bloodbaths.
Transit does experience more of a headache from induced demand pressure since it also uses large vehicles, and the entire trip experience is contingent on not holding up that one train or bus - while Tokyo's system works, the crowding is notorious, and the train stations have sizable footprints. But as a collective effort, it can also be much more coordinated and deliver useful results from capacity increases.
[+] [-] labster|4 years ago|reply
Just watch out for freshmen at the first rainstorm. You can tell them apart by their freshman stripe — the result of not having a rear fender.
[+] [-] danhor|4 years ago|reply
[+] [-] thanatos519|4 years ago|reply
[+] [-] Lavery|4 years ago|reply
-Bike lanes (and ultimately, bike destinations) have way higher humans-per-square-foot of road / parking lot density than cars lanes. The throttling mechanism on behavior for the car example is ultimately drive time, and new lanes quickly become capacity constrained (first at the interchanges; later at the parking; last in the lanes themselves) in a way that slows ultimate travel back to the indifference equilibrium. The equivalent for bikes tolerates a way higher flow of humans.
-Induced demand for cars is in part a function of the fact that you can (up to a point) drive at any speed, meaning that if roads are added that support commuting in from 30, 40, 60 miles away, that can be a doable commute. There is no amount of development that will create a 60 mile bicycle commute. Here, the demand induction mechanism with travel lanes and housing is reversed: you need convenient housing to drive the demand for bike lanes.
[+] [-] tobylane|4 years ago|reply
[+] [-] 0wis|4 years ago|reply
[+] [-] sempron64|4 years ago|reply
Bike lanes are ableist and classist. Only healthy citizens with an excess of time and energy are able to use them for trips. The elderly, children, those with heart conditions, asthma, or many other health conditions, and anyone needing to transport anything heavier than their own body cannot use the lane. In most cities this represents a minority of the population. Creating exclusionary space for bicycles is the opposite of progressive policy and efficient urban design.
[+] [-] 0wis|4 years ago|reply
4 years ago, few bike lanes and very few bikes. Detractors of the newly created ones were arguing about the ressource waste.
Today it is one continuous line at rush hour and some lanes are completely jammed. I am not an expert, but what a change. The pandemic may have helped but it is a true transformation. Many people who would have never bike in Paris a few months ago now bike daily to commute. It certainly took more than just laying lanes, planning and choosing the right places to create lanes has certainly a lot to do with it. But once the main places were connected by safe lanes, it began and never stopped.
Millenia-old super dense city certainly helps too, nonetheless many thought it would be impossible. Would probably be harder in a less crowded place.
First and most recent english article I found about it : https://thewest.com.au/travel/europe/parisian-pedal-power-ng... Not the most precise, but describes well the feeling.
[edit] : typo and spacing
[+] [-] Ajedi32|4 years ago|reply
> In 1941, your kid might have walked 15 minutes to the neighborhood school. In 2021, you drive your kid 15 minutes to school. Oh, and this isn't your choice: they tore down the old school and replaced it with a parking lot.
> In 1961, you might have biked or driven a few blocks to a corner store for milk and eggs. In 2021, you drive 3 miles to Kroger for milk and eggs, and there is no corner store. Has your utility increased? Or are you mostly just consuming more resources?
I would argue that utility _has_ increased; It's just that the market has re-organized itself such that the increased utility comes in the form of more flexible locations for houses and businesses rather than in the form of decreased commute times. One grocery store every 5 miles costs far less to maintain than 100 corner stores distributed evenly throughout the city, and you can get more house per dollar buying a house in the suburbs rather than if everyone were competing to buy housing smack-dab in the middle of a city.
I think perhaps a stronger version of the author's argument would be to point out that road use is an externality. Building more efficient roads comes at a significant cost, but road users don't pay that cost in a manner proportional to their use of those roads. Therefore the market does not factor in road construction costs when deciding how to organize cities, only costs of the transportation itself like commute times and gas usage.
I dislike the term "induced demand" for the same reason the author gave. "Induced demand" is really just "demand"; all economic systems work that way. The only thing different about roads is that our current system of road construction funded primarily by income taxes makes road use an externality.
[+] [-] aqme28|4 years ago|reply
I'm not at all convinced that this is true. It would make sense in a vacuum, but there are a lot of negatives from the road infrastructure necessary for large driving-only grocery stores.
Dense cities have lots of smaller grocery stores rather than a few large ones. I'm sure there's a reason for that.
[+] [-] sudosysgen|4 years ago|reply
[+] [-] imtringued|4 years ago|reply
The only difference is the appearance that the demand is truly endless. Building roads is a subsidy to cars. People don't pay for the roads they get for free. The optimal strategy becomes driving because public transport is "inconvenient" because the alternative to bad public transport isn't better public transport, it's more cars. So, now the entire city wants to drive. Of course, the problem with that is that cars are such an inefficient means of transport that it's impossible for everyone to drive. The fairy tale of induced demand is born.
[+] [-] Lendal|4 years ago|reply
Two years ago, the highway nearby completed a 5-year widening project. During that time, traffic was so bad I had to check Google Maps every day to find out which route I should use. Now that the project is complete, I never check Google Maps anymore. I just use the highway without even bothering, as the cost to drive on it is now clearly the cheapest. My life is better in the short term, but eventually more homes will be built, traffic will increase, at some point I'll have to go back to checking Google Maps every day, and they'll start another road-widening project.
I've lived here long enough to experience this cycle first-hand, and nothing has changed logically that would stop this loop from executing again and again. At some point, I'm sure a physical limit will be reached. Either we run out of space, or run out of money, or something else.
[+] [-] breput|4 years ago|reply
[+] [-] unknown|4 years ago|reply
[deleted]
[+] [-] srg0|4 years ago|reply
A single road can attract travels which begin or end far away from the road. So its effect is felt on a larger territory and further away. A road needs only few exits to be connected to other roads.
Bike lanes are more like capillary network than arteries. A single bike lane is almost useless, because it can serve only travels which begin and end in a narrow strip around the lane (maybe a block away). Two bike lanes which are not connected will be used much less than two connected lanes. Even a single discontinuity of the network can make bike travel unfeasible.
So rather than talking about lanes, we should talk about lane networks and their density. And up until certain density the network won't be used much. Only after reaching that threshold we can talk about effects it may have on city development. Similarly, a car road will not generate induced demand nor attract much traffic if it is missing a bridge across the river.
Let say a bike lane attracts traffic if the starting point and the destination are within w/2 from the lane. Let's assume uniform distribution of potential starting and destination points. Then in a city area A, a bike lane of length L will attract only Lw/A potential commutes (within a strip around the lane). There are two important observations to be made: 1) the induced demand is proportional to the length of the network L, 2) parameter w is probably small, likely ~ 200m, so 1 km of a bike lane will have a smaller and more local effect than 1 km of the road. To cover 1 km² of urban area, the well connected network would have to be a grid with the total density of bike lanes ~ 10 km / km².
[+] [-] Tade0|4 years ago|reply
It's not the cars - they're just tools. It's the insatiable appetite for living space.
There's a trend in the city I grew up in(Warsaw, Poland) that started over 20 years ago and continues to this day - people grew tired of living in crammed, Plattenbau apartments, so they moved to smaller towns(in part inspired by their notion of how Americans live) adjacent to big cities where all the jobs were. Additionally at that time interest rates were so high that this was an option for those who couldn't get a mortgage for an apartment.
Cars followed, but not everywhere. Places close to railways were an exception, but only up to a point, because over time commuters exhausted any spare capacity there was, so the remainder had to drive and bear the not insignificant costs of that. In the meantime a highway was built, but that didn't help for long.
Was Warsaw hollowed-out by this? Hardly. What happened instead is that it started cannibalizing smaller (but still relatively large) cities.
[+] [-] forrestthewoods|4 years ago|reply
Will building more lanes “solve” congestion? No! Will building more lanes allow more people to get to more places? Yes!!!
Latency and throughout are two different metrics. Building more road does not necessarily reduce latency. However it does increase throughput. This means more people have more access to economic opportunity; and that’s a good thing.
[+] [-] kazinator|4 years ago|reply
Bike lanes will not induce much demand if all you have is human-powered cycles. Maybe on sunny days, in flat areas.
[+] [-] exogen|4 years ago|reply
I rode my bike across the country and my favorite city for cycling is still Cleveland. Not a whole lot of bike lanes, but wide enough roads and flat terrain. And the only time I was ever struck by a vehicle was when I was riding in a bike lane (because they were trying to turn right).
[+] [-] URSpider94|4 years ago|reply
[+] [-] Scott_Sanderson|4 years ago|reply
Only 1% of people are brave enough to do this.
For bikes to have a significant mode share, it has to be more comfortable than "just mix in with the high speed SUVs."
Plenty of examples of high mode share, Copenhagen and Amsterdam above 50%, and they do not ask bicyclists to mix with fast dangerous cars.
[+] [-] jiri|4 years ago|reply
Physical separation is needed for lanes with radically different speeds. Today, sidewalks (4 kmph) are separated from cars (40+ kmph). Because of demand of people traveling around 20 kmph, we need another separated lane for bikes and other e-mobility crowd that is able to move approx. in range of 10-30 kmph. Because of safety new lane must be physically separated.
Also, there should be wise to set some speed limit for these lanes, like 30 kmph, for cases when lane is used by hi-powered e-mobility vehicles.
In theory, parts of town where car speed is so limited to speed of bikes (25 kmph?), separation in many cases disappear. Nobody wanna be driving in such speed anyway.
[+] [-] xyst|4 years ago|reply
US cities need to be built around bikes. There are known models that work (Amsterdam). There just needs to be a significant paradigm shift in American mindsets and dependency on vehicles.
[+] [-] andylynch|4 years ago|reply
[+] [-] notfbi|4 years ago|reply
- Roads/cars often leads to the phenomena of something like grid-lock. A network might be able to throughput 100 cars a minute when only <=100 cars are trying to get through, but try 101 and it starts dropping: If 120 cars attempt passage at once, congestion actually causes the throughput to drop to like 80 (think of those backward-propagating traffic-wave videos). If 150, throughput drops to 70 etc.
- You can add more roads/highways but if it doesn't address certain chokepoints, that throughput will still start descending at some point (though maybe a bit higher now like 110 cars/minute).
- Sometimes you can address the chokepoints, but after some expansion the remaining chokepoints are essentially having the buildings and city intersections themselves, at which point you can only address the bottleneck by rebuilding buildings further apart, which leads to a cycle of worsening pedestrian access, local-depopulation, and more cars.
- And then finally, maybe bikes are different in that they are small and agile with a congestion-failure-mode of being walked. It's hard or unlikely to get to a bike usage level that would lead you to want to move buildings very far apart to support them.
- Or maybe bikes are just simply so small that the preferred distance between buildings anyway (for sun light, privacy) can support most realistic biking numbers (which would be limited by density limits anyways: elevators only practically go so high, commuting biking trips can only be so far).
- Ultimately I wish there as a bit more explained here, maybe by someone that designs traffic/city simulations if that's how the best cost/benefits are tested now. It's really confusing that urban planning advocates concentrate on the un-improving car-trip-time/congestion KPIs like it's a dunk when it really seems some throughput-capacity utility metric would be more important.
[+] [-] TedShiller|4 years ago|reply
It applies to things like traffic, and yes, housing.
If building more housing lowered rents, I could finally afford a place in NYC, or LA, or SF. Unfortunately it doesn't work that way. But I wish it did.
[+] [-] locallost|4 years ago|reply
1) more roads means less space for houses 2) this means people live farther away from where they need to go 3) this means they are more dependent on their cars 4) this means there is inevitably congestion and you need more roads 5) go to 1
[+] [-] freen|4 years ago|reply
Thus, if you wish to decrease your commute as a driver, the best possible strategy is to advocate for increased alternatives.
[+] [-] harpiaharpyja|4 years ago|reply
[+] [-] choeger|4 years ago|reply
[+] [-] ummonk|4 years ago|reply
[+] [-] wpm|4 years ago|reply
I only live in the city I do because with a car payment, it would have cost more for me to live in the suburbs. In the city I can ditch the car.
[+] [-] ggm|4 years ago|reply
And luckily, except for outside Amsterdam Centraal and a couple of other places, it doesn't matter: The fixed and variable parameters of the model are far above where we want to be and far above where we would be, if we reduced single occupancy car-type vehicle use.
If we include the crazy, semi-fatal Dutch microcar, I think we might get to the worst of both worlds: thousands of people old and young driving microcars like they are in Legoland on a toy road, but the road isn't toy.
[+] [-] LordKano|4 years ago|reply
[+] [-] d--b|4 years ago|reply
I’d say induced demand applies to any kind of suitable way of commuting
[+] [-] PeterisP|4 years ago|reply
What I'm seeing in a city with growing bike infrastructure is the increased attractiveness of city homes which are "mid-distance" from jobs i.e. places which are too far to be walkable but within biking distance - if you have to use a car anyway, then you might as well go a bit further and get a suburban home instead, but biking augments public transportation in allowing a bit larger "dense city" instead of a lot larger suburban sprawl.