Induced Demand Debunked with one Chart

[kphoger]

one guy actually brought the SHOPPING CART on and proceeded to argue with the driver until the driver let him stay.

You mean this ...



... or this?



I've personally carried the latter onto a bus several times, back when I couldn't afford to own a car at all and lived 1½ miles from the nearest grocery store.

[HighwayStar]

one guy actually brought the SHOPPING CART on and proceeded to argue with the driver until the driver let him stay.

You mean this ...



... or this?



I've personally carried the latter onto a bus several times, back when I couldn't afford to own a car at all and lived 1½ miles from the nearest grocery store.

The former, and it was not full of groceries, it was full of TRASH 

[hotdogPi]

Empty 5¢ deposit cans are not trash.

[HighwayStar]

Empty 5¢ deposit cans are not trash.

Yes they are, they are filthy, they smell, they were thrown out, therefore they are trash. And they have no business on public transport.

[hotdogPi]

New York (the state, not just the city) says that any places that sell 5¢ deposit cans must also accept them for 5¢ each; in an urban area, that means you're always within walking distance of a place where you can deposit them, so public transit would not be required to get your deposit back. (Unfortunately, most business owners don't know this.) I don't know if this applies everywhere with bottle deposits or just New York, though.

[kphoger]

Empty 5¢ deposit cans are not trash.

Yes they are, they are filthy, they smell, they were thrown out, therefore they are trash. And they have no business on public transport.

I agree.  Just because something can be recycled, that doesn't mean it isn't trash.  One man's trash is another man's treasure, they say, but that doesn't mean it ceases being trash.

[jamess]

I dont think the chart debunks anything because of the scale. When people talk about induced demand, they talk about key links, not the overall road network.

Imagine you have a town along the river. Across the river, there is nothing. A bridge is built. People start building houses on the other side and traveling back and forth. Demand to cross the river went from 0 trips a day to 10,000 thanks to the bridge. Thats induced demand.

While thats an extreme example, the same is true when highways are built/widened leading to open space. What used to be a 1 hour trip to the CBD is now 20. People start buying up the land and building homes because people care about time to jobs, not miles. 

You can also induce demand via transit. Theres a famous NYC photo with subways being built to empty land. As expected, homes popped up soon after.

In fact, many of the first transit companies were simply real estate companies. They built trains for the express purpose of selling real estate.

Induced demand is a well studied and proven phenomenon. Your chart debunks it in the same way that holding a snowball in the senate debunks climate change.

[hotdogPi]

There can be several key links where building one will take it off another. For example, if there's a Long Island Sound crossing built, eastern Long Island will get more traffic, but it will take traffic off horribly congested I-95 in Connecticut and likely some western Long Island roads (for drivers who no longer have to go around the Sound).

[jamess]

And to add to my comment, I just came across this article that notes how induced demand can also include other modes.

The researchers collected data, including the lengths of new bike lanes and data from bike counters, from 106 cities across Europe. The bike counters allowed the researchers to measure the number of cyclists citywide, not just on the new bike paths. They analyzed the number of cyclists from March through July and found that in cities that had added bike lanes, cycling increased 11 percent to 48 percent more than in cities that had not added bike lanes.

The researchers found that the increase held when controlling for weather and changes in public transit supply and demand.

https://www.nytimes.com/2021/04/01/climate/bikes-climate-change.html

Of course someone will counter it with "they built a bike lane near my house and no one uses it," as if an anecdote trumps data from 106 cities (!)

[kernals12]

I think we should switch tactics to counter the Big Lie of induced demand. Rather than saying a highway expansion will reduce congestion, we should say that it increases mobility. It means people can access more affordable housing further from where they work, it means they can make more visits to their relatives, and they can more frequently go out to the countryside on the weekend.

[jeffandnicole]

And to add to my comment, I just came across this article that notes how induced demand can also include other modes.

The researchers collected data, including the lengths of new bike lanes and data from bike counters, from 106 cities across Europe. The bike counters allowed the researchers to measure the number of cyclists citywide, not just on the new bike paths. They analyzed the number of cyclists from March through July and found that in cities that had added bike lanes, cycling increased 11 percent to 48 percent more than in cities that had not added bike lanes.

The researchers found that the increase held when controlling for weather and changes in public transit supply and demand.

https://www.nytimes.com/2021/04/01/climate/bikes-climate-change.html

Of course someone will counter it with "they built a bike lane near my house and no one uses it," as if an anecdote trumps data from 106 cities (!)

Trying to read the data, I noticed this bit of info:

Bicycle Counter Data.
...This means that we investigate percentage changes rather than absolute increases in the number of cyclists...

If cities that increased bike lanes had low utilization of existing bike lanes, it wouldn't take much to increase the percentage.  Let's say, there were 100 bicyclists, and additional bike lanes added 50 bicyclists, that's an increase of 50%.

But if cities already had a large existing network, and numerous bicyclists using them, it would take a substantial number of additional people to get the same percentage increase.  If a location has 10,000 bicyclists, and there's another 50 bicyclists even though a new lane wasn't added, that's an increase of 0.05%.

Thus, the report is flawed.  Same number of people started using bicycles in each city, but by playing with numbers to support the researcher's conclusion, they ignored the numbers of bicyclists and went with percentages instead.

[michravera]

And I think we need to define the terms carefully:  induced demand vs latent demand.

When we build a completely new road, ALL use of the road is "induced demand". No one previously used the road BECAUSE THEY COULDN'T. It wasn't there.

The biggest relief on a limited access road comes from widening them from 2 lanes to 3 per direction. In the disciplined parts of California, adding a third lane goes from "Trucks, slow vehicles, and exiting traffic" mixing it up in the right lane and "Through traffic, fast vehicles, and passing" mixing it up in the right with 2 lanes to, in the case of three lanes, "Trucks and exiting traffic" on the right, "through traffic and those passing slower traffic" in the middle, and "Passing and fast through traffic on the left". With 3 lanes everybody stays more or less where they belong until they feel that they don't belong there anymore. In addition, the third lane increases the theoretical capacity by 50%. Because of queuing, the formula q=r/(1-r), when the road is at, say 75% capacity, says that q=0.75/0.25=3. When we add a lane, we are at only 50% capacity and get 0.5/0.5=1, so there is 3 times less conflict.

As otherwise proposed, adding a seventh lane to a roadway that is already 6 lanes in that direction only helps a little. It is also usually more expensive to try to add a 7th lane than possibly to build a whole new roadway with 2 lanes in each direction. The new roadway has the advantage that, if they pick the right of way properly, some people might actually have wanted to go where the new road goes and get off of the existing road.

[Scott5114]

Of course someone will counter it with "they built a bike lane near my house and no one uses it," as if an anecdote trumps data from 106 cities (!)

It really helps to look at bike lanes as a system. My street has a bike lane that nobody uses, but that's because at either end it runs out to four-lane arterials with no bike lanes. So of course nobody uses it, because once you get to the end of it there's no bike lanes to take you where you actually want to go. If you're going to add bike lanes, you need a system of them that connect with each other and provide options for actual routes.

And I think we need to define the terms carefully:  induced demand vs latent demand.

When we build a completely new road, ALL use of the road is "induced demand". No one previously used the road BECAUSE THEY COULDN'T. It wasn't there.

No, it's serving latent demand. For it to be induced demand you'd have to have people making the decision to drive more because of the new road. Nobody does that. The traffic on the new road is being removed from existing roads.

[kphoger]

It really helps to look at bike lanes as a system. My street has a bike lane that nobody uses, but that's because at either end it runs out to four-lane arterials with no bike lanes. So of course nobody uses it, because once you get to the end of it there's no bike lanes to take you where you actually want to go. If you're going to add bike lanes, you need a system of them that connect with each other and provide options for actual routes.

OTOH, any such system gets built one bike lane at a time.