Oh The Urbanity!
4 HN recommenders · recommended in 4 months, 2022–2024
8:05 · 291K views · Aug 29, 2021
Explains induced demand beyond roads, showing that it applies to transit, walking and cycling infrastructure too but with different consequences. It corrects common misunderstandings of the concept.
HN recommends it as a clear treatment of induced demand across transport modes whenever threads debate road expansion versus transit.
4 comments from Hacker News
There's a number of key differences, mostly in how things scale with increased use. * Car transit is typically scaled through increased space allocation. Public transit is typically scaled through increased utilization of the same space. * Car transit is limited at about 2000 vehicles/lane/hour. Public transit is mainly limited by the number of buses/trains on a route. (e.g. A typical bus can carry 30-100 people. Replacing a lane of car transit with a dedicated bus lane drastically increases the throughput of that lane.) * If the number of highway lanes are doubled, followed by induced demand using that capacity, the result is a much less enjoyable experience driving. If the frequency of buses doubles, followed by induced demand using that capacity, the result is a much more enjoyable experience taking the bus, as the wait for the next bus is shorter. * There's a phase transition in public transit utilization that happens when buses/trains/subways arrive more often than once every 15 minutes or so. If a bus arrives once every hour, you need to carefully plan your day around that particular bus, arrive early to make sure you don't miss it, and waste a lot of time waiting. If a bus arrives once every 10 minutes, there's no need to plan ahead, and you just get on whichever bus arrives next. The Youtube channel "Oh the Urbanity" had a pretty good video on induced demand as it applies to both car transit and public transit [0], that I highly recommend. Most everything by the "Not
> Using 'induced demand' for good - I love it. Oh The Urbanity had a good video on this, "What People Get Wrong About Induced Demand": > In this video we explain why induced demand does apply to transit, walking, and cycling infrastructure, but with different consequences. * this video Transit, for example, can get better with more ridership: more train capacity is added to a line, and more frequent service may occur for better throughput. Both actions would improve service for each individual rider, so while while one may not want it "crowded", having it busy is good. While with roads, an individual driver may want enough traffic so that a street exists, any traffic beyond that would probably only slow you down. There are also externalities: more walking, cycling, transit reduces pollution and can improve individual health and the collective health of the population. Driving does the opposite.
> Did creating the iPhone induce demand for iPhones that otherwise would not have been there? Was there pent up demand for iPhones that was sated by their creation? Invention is the mother of necessity. — Marshal McLuhan > In the same way, it seems strange to term things induced/pent up demand. Increased road capacity means people could plan more car trips without worrying about sitting in traffic. Until that new capacity is filled up and now you have even more people sitting in traffic. The only way to reduce traffic is to get people out of cars, otherwise you're just spending money to kick the can down the road. See "What People Get Wrong About Induced Demand" by the Oh The Urbanity! channel: * this video Also "Does Induced Demand Apply to Housing?": * [LINK]
> Cities should be inducing demand for getting around. This is mentioned in the latest NJB video, "More Lanes are (Still) a Bad Thing": > The difference for induced demand for cars, and induced for other modes of travel, is that cars are a extremely space inefficient. You can absorb a lot more induced travel demand on a subway line, tram line, or bicycle path, than you can in a car lane. * [LINK] The Oh The Urbanity! channel has a good video on this, "What People Get Wrong About Induced Demand": * this video Cars have (AFAICT) the lowest hourly through-put of any transportation mode: * [LINK]