Transit Networks Absorb Induced Demand While Urban Highways Choke

What People Get Wrong About Induced Demand — Oh The Urbanity!

Oh The Urbanity!

All transportation infrastructure generates induced demand, but rail and cycling convert higher volumes into increased service frequency and public benefits rather than the gridlock produced by car expansion.

AI-assisted summary of What People Get Wrong About Induced Demand — original source. Check the original for full context.

Source published:

Key ideas

  • Studies indicate that between 50% and 100% of newly constructed urban highway capacity is absorbed by additional traffic within just a few years, returning congestion to baseline levels. (0:48)
  • While Toronto's six-lane Don Valley Parkway moves only 6,000 to 8,000 people per direction per hour at peak, the two-track Yonge Subway line currently carries roughly 30,000, projected to reach 40,000 with signaling upgrades. (0:01)
  • Induced demand is not exclusive to road infrastructure; it applies equally to transit, walking, and cycling, but the resulting network effects and societal impacts differ drastically by mode. (0:48)
  • Unlike automobile congestion, transit demand produces positive feedback loops, allowing agencies to justify higher service frequencies, grade separation, and larger capacity vehicles. (3:30)

Detailed notes

## Background Published on YouTube by the urban planning channel Oh The Urbanity! on August 29, 2021, this video re-examines the mechanics of induced demand. According to the video description, while the phenomenon is frequently cited to oppose road expansions that fail to relieve congestion, the discussion explores why induced demand applies equally to transit, walking, and cycling infrastructure, but yields fundamentally different consequences.

## TL;DR While induced demand is commonly weaponized against highway widening because new lanes rapidly refill with cars, the video demonstrates that all functional transportation infrastructure naturally induces travel demand. Comparing Toronto's Don Valley Parkway with its subway corridors illustrates that mass transit absorbs vastly higher passenger volumes across a tiny footprint, turning high demand into a marker of success rather than a failure mode. Furthermore, while automobile congestion degrades travel conditions and carries steep spatial and environmental costs, induced demand in transit and active transportation triggers positive network effects, such as improved service frequencies and enhanced public health. Ultimately, the central question for city planners is not how to avoid inducing demand, but deciding which specific type of travel behavior a city wants to induce.

## Atmosphere & style The presentation carries a calm, measured, and intellectually constructive tone that swaps anti-car rhetoric for clear-headed structural analysis. Guided by an articulate, unhurried voiceover, the pacing feels methodically reasoned as it unpacks transit planning metrics and real-world Toronto case studies. The viewing experience feels quietly eye-opening, prompting the audience to move beyond standard urbanist catchphrases and look directly at the underlying mechanics of network capacity and urban geometry.

## Bulletin - [00:48](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=48s) Studies indicate that between 50% and 100% of newly constructed urban highway capacity is absorbed by additional traffic within just a few years, returning congestion to baseline levels. - [00:01](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=1s) While Toronto's six-lane Don Valley Parkway moves only 6,000 to 8,000 people per direction per hour at peak, the two-track Yonge Subway line currently carries roughly 30,000, projected to reach 40,000 with signaling upgrades. - [00:48](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=48s) Induced demand is not exclusive to road infrastructure; it applies equally to transit, walking, and cycling, but the resulting network effects and societal impacts differ drastically by mode. - [03:30](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=210s) Unlike automobile congestion, transit demand produces positive feedback loops, allowing agencies to justify higher service frequencies, grade separation, and larger capacity vehicles.

## Key takeaways - [00:01](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=1s) Passenger throughput differences between mass transit and urban highways are immense, with a two-track subway moving up to five times more people per hour than a six-lane highway. - [00:01](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=1s) Subway infrastructure carries vast crowds while occupying a minimal surface footprint compared to the massive urban land requirements of highways. - [00:48](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=48s) Induced demand—or induced traffic—occurs because expanded road capacity incentivizes drivers to alter trip timing, take additional journeys, and relocate closer to the expanded corridor. - [00:48](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=48s) Using induced demand solely as a weapon against car infrastructure is intellectually incomplete because transit and active mobility also induce demand. - [02:09](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=129s) In transit planning, induced demand is intentionally sought as 'induced ridership' to validate investments and encourage transit-oriented growth. - [02:09](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=129s) High transit ridership and occasional overcrowding are viewed as indicators of success and signals to expand network capacity, whereas road congestion represents systemic operational failure. - [03:30](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=210s) Mass transit can absorb substantially greater passenger volumes before reaching full capacity compared to automotive lanes. - [03:30](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=210s) High transit ridership triggers positive network improvements such as increased service frequency and vehicle upgrades, benefiting individual riders instead of merely slowing them down. - [03:30](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=210s) Transit systems feature built-in pricing levers through fares and subsidies, whereas road pricing and tolls face intense public and political pushback in North America. - [05:43](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=343s) Expanding pedestrian and cycling infrastructure induces active trips, yielding public health benefits without the lethal safety risks, air pollution, or noise generated by cars. - [05:43](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=343s) Active transportation and mass transit demand relatively modest capital and spatial footprints, avoiding the neighborhood demolition historically required for urban highways. - [05:43](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=343s) The primary flaw of automotive infrastructure is not that it induces trips, but rather the severe negative externalities and spatial inefficiency of cars in dense urban environments. - [05:43](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=343s) The fundamental policy question for cities is not which transportation infrastructure induces demand, but which type of demand a community chooses to induce.

## Detailed walkthrough ### [00:01](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=1s) The Capacity Chasm: Subways vs. Urban Highways

While it is widely accepted that public transit moves large crowds far more efficiently than private automobiles, public discourse rarely emphasizes the staggering scale of that gap. A direct comparison between two major corridors in Toronto illustrates this disparity vividly. On the Don Valley Parkway (DVP), a six-lane highway, observing peak rush-hour traffic reveals that only about 6,000 to 8,000 people pass by in the busier direction over the course of an entire hour. Meanwhile, on the nearby Yonge Subway line, the system currently moves roughly 30,000 people per direction per hour, with in-progress signal modernizations expected to elevate that threshold to 40,000.

```mermaid flowchart LR accTitle: Capacity Comparison Between Highway and Subway accDescr: Chart comparing passenger throughput per direction per hour between the Don Valley Parkway and the Yonge Subway.

subgraph Highway["Six-Lane Highway (DVP)"] DVP["6,000 to 8,000<br/>passengers/hr/dir"] end

subgraph Subway["Two-Track Subway (Yonge Line)"] YCurrent["Current: 30,000<br/>passengers/hr/dir"] YFuture["Future Upgrades: 40,000<br/>passengers/hr/dir"] YCurrent -.-> YFuture end ```

The physical footprint makes the numbers even more striking: the subway achieves this massive volume occupying only two tracks, primarily buried underground, whereas the highway consumes six full lanes of valuable urban surface. As the narrator underscores: “Subways don’t carry freight, but when it comes to carrying lots of people, mass transit wins hands down and it’s not even close.”

- **Don Valley Parkway (DVP)**: 6 lanes carrying 6,000–8,000 people per direction per hour at peak. - **Yonge Subway line**: 2 tracks carrying 30,000 people per direction per hour currently; projected to reach 40,000 with signaling upgrades.

---

[00:48](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=48s) The Mechanics and Misconceptions of Induced Demand

Anyone following debates over roadway expansions is likely familiar with "induced demand"—often more accurately described as "induced traffic"—popularized by media outlets like Vox with colorful ball visualizations to campaign against new highway projects. The core premise is straightforward: expanding road capacity fails to resolve traffic congestion over the long term because it incentivizes more driving. Motorists who previously adjusted their schedules to avoid rush hour become careless about departure times and trip frequency. Concurrently, residents and commercial enterprises migrate toward the expanded corridor to capitalize on the open asphalt. Consequently, congestion inevitably returns to baseline levels.

Empirical urban research confirms this is not an illusion: studies show that between 50% and 100% of newly constructed road capacity in urban centers is absorbed by additional traffic within just a few years. It is not an infinite phenomenon—building a massive highway in remote wilderness will not magically conjure traffic—but it holds true in populated areas. Yet, framing induced demand exclusively as a weapon against car infrastructure remains intellectually incomplete. If building a new subway route leads to packed trains a few years down the line, critics could theoretically argue that subways suffer from the exact same failure mode.

> “However, the induced traffic argument against new car infrastructure has always seemed, maybe not wrong, but certainly incomplete, because why does it only mention cars?”

---

[02:09](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=129s) Induced Ridership: The Goal of Mass Transit

To resolve overcrowding along the Yonge line and its bottleneck transfer point at the Bloor-Danforth Line, Toronto transit planners designed the Ontario Line, an automated rapid transit line intended to supply much-needed capacity through the city's east end. This project functions under the exact same dynamic as road building, except planners designate it "induced ridership." The line will encourage existing residents to take more journeys and attract new residents into growing east-end transit-oriented neighborhoods. Eventually, the Ontario Line will likely become congested as well.

The critical distinction lies in planning intent. While traffic engineers view traffic gridlock as a systemic failure, mass transit authorities view high ridership as success. Even though excessive overcrowding degrades the passenger experience, safety, and operating efficiency, reaching maximum capacity does not invalidate the original investment. Rather, it validates the project's utility and signals the necessity of building the next line. As the narrator observes: “The Yonge line is overcrowded now and no one thinks that means it shouldn’t have been built.”

- **Planned Ontario Line top capacity**: 34,000 passengers per hour per direction. - **Overcrowding perspective**: High passenger volume proves utility and justifies follow-up transit infrastructure; having an overcrowded transit line is far preferable to lacking one entirely.

---

[03:30](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=210s) Why Induced Demand Favors Transit Over Cars

The reason induced demand feels threatening when applied to cars, but positive when applied to trains, rests on structural differences in capacity, system dynamics, and economic mechanisms:

```mermaid flowchart TD accTitle: Mode Dynamics Under High Demand accDescr: Diagram illustrating how added demand impacts driving negatively versus transit positively.

subgraph Driving["Car Driving Infrastructure"] CarD["Increased Road Demand"] --> Congest["Severe Traffic Congestion"] Congest --> CarWorse["Experience Degrades for All Users"] CarWorse --> RoadTolls["Pricing (Tolls) Politically Unpopular"] end

subgraph Transit["Public Transit Infrastructure"] TrD["Increased Transit Demand"] --> AgencyAction["Agency Adds Capacity<br/>(Higher Frequencies, Grade Separation)"] AgencyAction --> TrBetter["Service Improves for Individual Riders"] TrBetter --> Farebox["Built-In Pricing Mechanism<br/>(Fares & Subsidies)"] end ```

First, transit can absorb immense passenger volumes before becoming overwhelmed. Pitting the planned Ontario Line (34,000 passengers per hour per direction) against a hypothetical six-lane highway matching the DVP (6,000 to 8,000 passengers per direction per hour) reveals that both attract trips, but the car highway will choke on its own demand orders of magnitude faster.

Second, mass transit exhibits positive network feedback where high ridership triggers operational improvements. When a transit agency responds to rising demand, the remedies—elevating service frequencies, substituting buses with rail vehicles, granting transit signal priority, or converting surface routes into tunneled or elevated rights-of-way—directly improve convenience for individual passengers. For motorists, other cars represent purely negative competition that slows down travel. The narrator crystallizes this dynamic: “No one wishes for more drivers on their road to get more lanes, but you might wish for more ridership on your transit route so that you can get better frequency.”

Third, transit systems possess a built-in pricing lever. A transit agency can manage demand simply by raising standard ticket or transit pass prices, accompanied by targeted low-income subsidies to safeguard equity. In contrast, managing car traffic requires cordon pricing or toll roads, which face intense political resistance across Canada and North America. Relying on fuel taxes remains ineffective as a congestion pricing substitute because drivers easily evade it by purchasing fuel-efficient cars or refueling in adjacent tax jurisdictions.

---

[05:43](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=343s) Active Mobility and the Core Question of Urban Planning

Induced demand also governs active transportation, including walking and cycling infrastructure. If an overcrowded multi-use trail is expanded to provide segregated facilities for cyclists and pedestrians, the improvement will induce more people to walk and ride bikes. Rather than sparking municipal backlash, this shift yields widespread public benefits: - **Public Health**: Elevated levels of routine physical activity directly bolster public health outcomes. - **Absence of Negative Externalities**: Pedestrians and cyclists generate virtually no noise pollution, toxic exhaust, or lethal safety risks for surrounding neighborhoods. - **Spatial and Financial Footprint**: Active infrastructure demands minimal capital expenditure and physical space. While countless historic North American urban neighborhoods were bulldozed in the mid-20th century to construct urban highways, modern protected bike lanes require no neighborhood demolition.

```mermaid flowchart TD accTitle: The Universal Mechanism of Induced Demand accDescr: Flowchart demonstrating how urban infrastructure design choices dictate travel behavior and personal lifestyle decisions.

Choice{"Infrastructure Built"}

Choice -->|"Wider Roads"| DriveLife["People drive more & organize lives around cars"] Choice -->|"Fast Transit Lines"| TransitLife["People ride transit & organize lives around transit"] Choice -->|"Safe Bike Networks"| BikeLife["People bike more & organize lives around cycling"] ```

Ultimately, invoking induced demand solely as a generic weapon against road expansion misses the forest for the trees. The core flaw of automotive infrastructure is not merely that it induces trips—every well-designed transportation system induces trips by connecting destinations. The fatal flaw lies in the negative externalities of the automobile and the unforgiving spatial geometry of cars operating within dense cities. In the narrator's concluding words: “The question isn’t really which types of transportation infrastructure induce demand, because they all do; the question is which type of demand you want to induce.”

## Notable quotes > [05:43](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=343s) The question isn’t really which types of transportation infrastructure induce demand, because they all do; the question is which type of demand you want to induce.

> [03:30](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=210s) No one wishes for more drivers on their road to get more lanes, but you might wish for more ridership on your transit route so that you can get better frequency.

> [00:01](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=1s) Subways don’t carry freight, but when it comes to carrying lots of people, mass transit wins hands down and it’s not even close.

## Mentioned Oh The Urbanity!, Don Valley Parkway, Yonge Subway line, Vox, Bloor-Danforth Line, Ontario Line, Metrolinx, Toronto

## Video description Induced demand (probably more accurately called induced traffic) is the phenomenon where building or expanding roads and highways doesn't help congestion because it results in more people driving. This is often used as an argument against building the new car infrastructure, but people don't talk often about how induced demand applies to other modes. In this video we explain why induced demand does apply to transit, walking, and cycling infrastructure, but with different consequences.

Support our work/watch more: Patreon: https://www.patreon.com/ohtheurbanity Urbanism playlist: https://www.youtube.com/playlist?list=PLN3OhfIDlvuMjcg36sdLJuxaXi6OaOWFD Subscribe for more videos: https://www.youtube.com/channel/UCN5CBM1NkqDYAHgS-AbgGHA?sub_confirmation=1

More information: Visualizing the Footprint of Highways in American Cities: https://www.visualcapitalist.com/visualizing-the-footprint-of-highways-in-american-cities/ Metrolinx Ontario Line report: http://www.metrolinx.com/en/docs/pdf/board_agenda/20190912/20190912_BoardMtg_Ontario_Line_Initial_Business_Case_EN.pdf

#urbanism #induceddemand #transit #toronto #ontarioline #metrolinx

[Source](https://www.youtube.com/watch?v=8wlld3Z9wRc)

中文简报

公交网络有效吸纳诱导需求，城市公路则陷入拥堵瘫痪 所有交通基础设施都会产生诱导需求，但铁路和骑行能将更高运量转化为发车频次提升和公共效益，而非小汽车扩张所带来的交通瘫痪。 尽管由于新增车道会迅速重新被车辆填满，诱导需求常被用作反对公路扩建的论据，但该视频表明，所有能正常运转的交通基础设施都会自然引发出行需求。多伦多当谷园林公路与地铁走廊的对比表明，大众交通能以极小的占地面积吸纳高得多的客运量，使高需求成为成功的标志而非失败的表征。此外，尽管小汽车拥堵会恶化出行条件并带来高昂的空间与环境成本，但公交和慢行交通中的诱导需求却能触发积极的网络效应，例如提高发车频次和增进公众健康。归根结底，城市规划者的核心问题并非如何避免诱发需求，而是决定城市希望诱导哪种特定的出行行为。 研究表明，新建城市公路运力的50%至100%会在短短数年内被新增交通量吸收，使拥堵程度重回基线水平。 (0:48) 多伦多六车道的当谷园林公路在高峰期每方向每小时仅能运送6,000至8,000人，而双轨的央街地铁线目前运送约30,000人，且随着信号系统升级预计将达到40,000人。 (0:01) 诱导需求并非道路基础设施所独有；它同样适用于公交、步行和骑行，但不同出行方式所产生的网络效应和社会影响截然不同。 (0:48) 与小汽车拥堵不同，公交需求会产生正反馈循环，使运营机构有理由提高发车频次、实施立体交叉并采用更大容量的交通工具。 (3:30)

Reading summary

Urban infrastructure of every kind induces demand by encouraging people to use it, but framing this phenomenon solely as an argument against car infrastructure overlooks how transit and active mobility transform added demand into public benefits. The Scale Gap in Passenger Throughput (0:01) While mass transit is recognized for moving crowds efficiently, the difference in sheer capacity compared to urban highways is often understated. In Toronto, the six-lane Don Valley Parkway moves approximately 6,000 to 8,000 people per direction per hour at peak rush hour while consuming extensive surface space. In contrast, the two underground tracks of the Yonge Subway line carry roughly 30,000 people per direction per hour, with signaling upgrades projected to raise that figure to 40,000. This physical footprint illustrates that mass transit operates at an entirely different scale for passenger volume. While highways cannot easily expand without claiming vast swaths of valuable land, rapid transit achieves multiple times the throughput within a fraction of the physical corridor. The Incomplete Critique of Induced Traffic (0:48) Opponents of highway expansions often cite induced demand—the empirical reality that 50% to 100% of newly built urban road capacity is absorbed by traffic within a few years as motorists alter trip times and new developments cluster along corridors. However, using induced demand solely to critique automobile infrastructure is intellectually incomplete. If building a new subway line results in full trains years later, applying the same logic would classify that transit project as a failure. In public transit planning, this identical dynamic is termed 'induced ridership' and represents the primary policy objective. Toronto's planned Ontario Line, designed for a capacity of 34,000 passengers per hour per direction, aims to draw passengers and foster transit-oriented communities. While severe overcrowding causes operational challenges, high transit usage validates an investment's utility and signals the need for additional lines rather than discrediting the original project. Network Feedback and Demand Management Mechanisms (3:30) Induced demand harms road networks while benefiting public transit due to structural differences in capacity and operational feedback loops. A highway chokes on added demand far faster than a rail line because individual cars represent negative competition that slows down travel. Conversely, rising transit ridership justifies higher frequencies, vehicle upgrades, and dedicated rights-of-way, which directly improve service quality and convenience for individual passengers. Transit systems also feature established demand management tools that highway authorities struggle to replicate. Transit agencies can adjust fares while deploying targeted low-income subsidies to protect equity. In contrast, managing car traffic requires tools like road tolls or cordon pricing, which face deep political resistance across North America, while fuel taxes fail as effective substitutes due to fuel-efficient vehicles and cross-jurisdictional fueling. Externalities and Urban Geometry Across Modes (5:43) Induced demand operates identically in active mobility: expanding separated trails and protected bike lanes induces more walking and cycling. Unlike vehicular traffic, induced active transit yields positive outcomes for public health and produces virtually no toxic exhaust, noise pollution, or fatal crash risks for adjacent neighborhoods. Moreover, bike networks and sidewalks require negligible capital expenditure and land, avoiding the community demolition that historically accompanied urban highway construction. The fundamental issue with private vehicles in cities is not that roads induce trips, but that the automobile's spatial geometry and severe negative externalities make vehicular volume unsustainable. Because every well-designed transportation system induces demand, urban planning ultimately dictates which mode of travel residents will organize their daily lives around. The debate over transportation investment should not center on whether infrastructure induces demand, as all functional transit, road, and cycling projects do. Instead, the central question for urban policy is deciding which specific type of travel behavior a city chooses to incentivize.

精炼阅读摘要

Oh The Urbanity! 指出，“诱导需求”并非仅存在于汽车道路扩张中，公共交通与主动出行同样具备诱导客流的机制；城市规划的核心分歧不在于基础设施是否会激发新需求，而在于城市决定诱导何种交通方式及其伴随的外部性。 空间几何与通行能力的客流差距 (0:01) 公共话语普遍承认公共交通在运载效率上优于私家车，但往往低估了两者在通行容量上的极端差距。以加拿大多伦多两条主要走廊为例，拥有六车道的顿谷园林公路（Don Valley Parkway, DVP）在早晚高峰时段，繁忙方向每小时仅能运送约6,000至8,000人；相比之下，仅占用双轨地下空间的央街地铁线（Yonge line）当前每方向每小时可运送约30,000人，随着信号现代化升级，该数值预计提升至40,000人。 作者强调，除了载客体量相差数倍，二者对城市地表空间的占用同样存在巨大差异。公路消耗了极具价值的城市地表用地，而地下地铁线路在极小的物理足迹下即可实现更高的运力。这证明在大规模客流集散场景中，轨道交通的空间利用效率具有压倒性优势。 诱导交通与诱导客流的评价分歧 (2:09) 在公路扩建争议中，“诱导需求”（通常更准确地被称为“诱导交通”）常被批评者用作反对新建道路的依据。实证研究显示，城市中心新建道路容量的50%至100%会在数年内被新增车流完全吸收，促使司乘人员放弃错峰出行或吸引企业与居民沿线聚集，最终导致拥堵重回基准水平。然而，作者指出，若将诱导需求单纯作为反车道基础设施的论据，在逻辑上是不完整的，因为轨道交通同样会诱导人流。 两者的根本差异在于规划预期与成败定义。交通工程师将道路再度拥堵视为系统性失败，但公共交通机构却将高客流量视作建设成功的标志。例如，多伦多规划中的安大略线（Ontario Line）设计最高运力为单向每小时34,000人，旨在缓解央街线换乘瓶颈，其设计初衷就是诱导沿线产生更多客流。即便地铁线路日后达到饱和甚至过度拥挤，客流饱和本身也印证了线路的公共价值，并成为启动下一条线路规划的合理依据，而非证明原项目投资失误。 网络正负反馈与需求定价机制 (3:30) 汽车与公共交通在面对额外需求时，展现出相反的系统动态反馈。对道路使用者而言，新增车辆属于纯粹的负面竞争，会直接降低所有用户的行驶速度；但对公共交通系统而言，客流攀升会触发良性网络反馈——交通部门可通过提升发车频率、以轨道替代公交、设置信号优先权或推动线路立体化来扩容，这些应对措施反过来直接改善了个体乘客的乘车体验。 在经济调控手段上，两者同样存在机制差异。公共交通机构拥有内置的票价调节杠杆，能够通过调整普通车票价格并配合低收入定向补贴来平衡供需与公平；相反，针对私家车的拥堵收费或道路收费在北美常面临极大的政治阻力，而燃油税又容易因节油车型的普及或跨区域加油行为而被规避，导致车流管理缺乏灵活性。 主动出行网络与城市发展选择 (5:43) 诱导需求同样支配着步行和自行车等主动出行方式。当多功能步道改扩建为行人和自行车分离的安全设施后，往往会诱导更多市民选择步行和骑行。与汽车交通带来的拥堵恶化不同，主动出行诱导出的需求具有显著的正向外部性：它能直接改善公众健康水平，且几乎不产生噪声污染、尾气排放或严重安全隐患。 此外，主动出行设施的资金与空间成本极低。20世纪中叶北美为修建城市高速公路曾大面积拆除历史街区，而现代保护型自行车道的建设完全无需拆迁社区。这表明，诱导需求本身并非缺陷，而是所有有效连接目的地的交通网络均具备的中性特征，决定其价值的是具体交通工具在城市空间内的负外部性程度。 视频总结指出，将“诱导需求”局限在反对修路的论点中脱离了核心问题，因为高效的交通基础设施均会诱导出行。汽车基础设施的根本缺陷在于车辆巨大的空间占用与沉重的外部代价；城市规划者面临的关键抉择并非设法阻止需求被诱导，而是主动决定利用基础设施诱导何种出行模式与生活方式。

Detailed notes — zh

## Background 该视频由 YouTube 频道 Oh The Urbanity! 于 2021 年 8 月 29 日发布。视频简介指出，“诱导需求”（更准确地称为诱导交通）通常被用作反对修建新汽车基建的核心论据，但很少有人探讨其在公共交通、步行和骑行等其他出行方式中的表现，本期内容旨在剖析诱导需求在不同交通模式下的运作机制与截然不同的后果。 ## TL;DR 视频通过对比多伦多高速公路与地铁的运载能力，指出传统城市规划讨论中将“诱导需求”单纯作为反对汽车基础设施的论据是不完整的。主讲人阐明地铁、自行车道和步行设施同样会诱发更多使用需求，但公共交通具备更高的客流容量上限、正向网络规模效应以及灵活的定价调节工具，而微出行则完全没有汽车带来的噪音、污染与安全等负外部性。核心论点在于，诱导需求是所有交通设施的共性规律，城市规划的关键不在于避免诱导需求，而在于决定社会究竟希望“诱导”哪一种出行方式。 ## Atmosphere & style 视频展现了理性、冷静且极具思辨性的分析基调，叙事清晰有力且层层递进。主讲人以温和客观的口吻拆解了城市主义科普中常见的逻辑盲区，既不盲目煽情，也不陷入教条反车主义。整部内容通过精准的数据对比与多伦多本地实例，带给观众一种拨云见日般的智性启发，在结尾处更以幽默风趣的呼吁收尾，观感轻快且充满说服力。 ## Bulletin - [00:01](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=1s) 公共交通与道路的客运能力差距悬殊：以多伦多为例，双向六车道的当河谷园林公路（DVP）高峰期单向仅能运送6,000至8,000人/小时，而附近的央街地铁线目前单向已达30,000人/小时，信号升级后可提升至40,000人/小时。 - [00:48](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=48s) “诱导需求”（更准确地说是诱导交通量）并非私家车独有，城市地区新增道路容量的50%至100%虽会在几年内被车流填满，但新建地铁、自行车道和步行道同样会引发客流与出行量的激增。 - [02:09](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=129s) 诱导需求在公交系统中体现为“诱导客流”，这种拥挤不仅不是规划灾难，反而是项目成功并推动TOD（公交导向型开发）的证明，通常意味着需要在此基础上规划新建下一条线路。 - [06:35](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=395s) 反对汽车基建的核心不在于诱导需求本身，而在于汽车低效的几何空间占用及严重的负外部性；城市规划的根本问题在于决策者究竟希望诱导哪一种出行需求。 ## Key takeaways - [00:01](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=1s) 多伦多央街地铁线仅占用两条轨道，其单向高峰运力（30,000-40,000人/小时）即达到六车道DVP高速公路（6,000-8,000人/小时）的数倍，体现了公共交通在大规模人员转运上的压倒性优势。 - [00:48](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=48s) 诱导交通（Induced Traffic）常作为反对修建道路的核心论据，研究表明城市新增道路容量的50%至100%会在数年内被填满，但仅针对汽车讨论诱导需求是不完整的。 - [02:09](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=129s) 多伦多规划中的安大略线地铁同样会产生诱导效应，促使沿线居民增加出行并吸引新人口迁入，最终该线路在未来也有可能达到饱和。 - [02:09](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=129s) 公交系统的超载并不意味着项目是失败的，相反它验证了线路的高效实用性，为进一步追加轨交建设和推动TOD开发提供了充分依据。 - [03:30](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=210s) 地铁线路的基础运力上限极高（如安大略线规划单向达34,000人/小时），相比于运力较低且短时间内就会饱和的高速公路，能支撑更长久、规模更大的需求增长。 - [03:30](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=210s) 公共交通具备规模网络效应，客流量的增加会促使运营方提升发车频次、优化列车或升级信号，从而改善乘客整体体验；而道路上增加司机只会加剧延误与烦躁。 - [03:30](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=210s) 公共交通天然具备票价调节与拥堵定价机制来平抑过度需求，而针对私家车收取道路拥堵费或提高燃油税在政治和实践中阻力极大且极不受欢迎。 - [05:43](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=343s) 拓宽步道与建设自行车道同样会诱导更多非机动出行，但这种需求诱导能够直接增进公众健康，且几乎不产生噪音、空气污染或严重事故伤亡等负外部性。 - [05:43](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=343s) 自行车道和步行设施不仅造价低廉、极度节约土地，也绝不会像20世纪中叶北美建设高速公路那样导致整个社区被大面积拆毁抹去。 - [06:35](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=395s) 汽车基础设施的根本缺陷在于其在几何空间上的极端低效，给汽车分配再多土地也极易导致瘫痪，这才是反对道路无序扩张的底层原因。 - [06:35](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=395s) 城市公众的出行选择与定居决策始终跟随既有基础设施而变；交通规划的核心命题不是哪种设施会诱导需求，而是城市到底想要诱导哪一种交通需求。 ## Detailed walkthrough ### [00:01](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=1s) 运载能力的悬殊：多伦多高速公路与地铁的对比 公共交通在运送大规模人群时的效率远高于私家车，但两者的差距究竟有多大，往往未被充分讨论。以加拿大多伦多的当河谷园林公路（Don Valley Parkway, DVP）为例，这条双向六车道的高速公路在早晚高峰时段，车流密集方向一小时内仅能运送约 6,000 至 8,000 人。相比之下，附近的央街地铁线（Yonge Subway）单方向每小时已能运送 30,000 人；随着正在进行的信号系统升级，这一运力未来将进一步提升至每小时 40,000 人。这意味着，仅占用两条轨道（且大部分位于地下）的地铁，在客运能力上具有压倒性优势。尽管地铁无法运输大宗货物，但在大规模人员转运方面，主讲人强调：“Subways don’t carry freight, but when it comes to carrying lots of people, mass transit wins hands down and it’s not even close.”（地铁不载货，但在承载大量人群方面，公共交通完胜，而且差距悬殊。） - **当河谷园林公路（DVP）**：六车道高速公路，高峰期单向运力仅为每小时 6,000–8,000 人。 - **央街地铁线（Yonge Line）**：仅占两条轨道且多位于地下，目前单向每小时运送 30,000 人，完成信号升级后预计可达每小时 40,000 人。 --- ### [00:48](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=48s) 诱导需求不仅适用于私家车：对常见反驳视角的审视 在道路与高速公路扩建的讨论中，“诱导需求”（Induced Demand，更准确的说法是“诱导交通量” Induced Traffic）常被用作反对修建道路的核心论据。许多科普视频（例如 Vox 常用彩色小球做动画演示）解释称：增加道路通行空间并不能从长远上解决拥堵，因为新车道会诱导更多驾驶行为。新车道建成后，原本避开高峰期的司机会在出行时间和频次上变得不再谨慎，同时居民和企业也会被新路网吸引而搬迁至周边，最终导致道路在几年后重新陷入拥堵。 研究表明，城市地区新增道路容量的 50% 至 100% 会在几年内被彻底填满。诱导交通是一个不争的事实，但这套纯粹反对汽车基建的说辞并不完整。主讲人指出：“However, the induced traffic argument against new car infrastructure has always seemed, maybe not wrong, but certainly incomplete, because why does it only mention cars?”（然而，针对新增汽车基建的诱导交通论据一直显得——即便不能说错误——也必定是不完整的，因为为什么它只提及私家车？）如果新建一条地铁线路，几年后它也变得拥挤不堪，这是否也是一个需要避免的问题？实际上，步行、骑行与公共交通同样存在诱导效应，但其带来的后果却截然不同。 --- ### [02:09](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=129s) 地铁中的“诱导客流”：为什么拥挤的反面不是灾难？ 为缓解央街地铁线以及与布鲁尔-丹佛斯线（Bloor-Danforth Line）主要换乘站的过度拥挤，多伦多交通部门计划在城市东端修建一条全新的全自动无人驾驶地铁——安大略线（Ontario Line）。从逻辑上看，高速公路诱导交通的规律完全能套用在安大略线上，只是在这里它被称为“诱导客流”（Induced Ridership）。新地铁会促使现有居民增加出行频次，吸引新居民迁入东端社区，线路客流量持续攀升，在未来的某个节点，安大略线很可能也会变得拥挤不堪。 然而，如果有规划师以“这条线路最终会诱导过多客流从而变得拥堵”为由反对修建安大略线，同行只会觉得不可理喻。诱导客流正是规划安大略线的核心目标，其初衷就是推动以公共交通为导向的社区开发（TOD）。我们期望人们去使用新地铁，无论是替代私家车出行还是完成以前无法实现的出行。尽管严重超载会损害安全性、运行效率与乘客体验，但这绝不意味着项目毫无用处： > “If and when that happens, it wouldn’t mean the Ontario Line was useless and shouldn’t have been built in the first place. It would mean the Ontario Line was really useful and we should probably build another subway line.”（如果并且当超载发生时，这并不意味着安大略线毫无用处、当初不该建；这恰恰说明安大略线非常有用，我们大概应该再建一条新地铁了。） 现在的央街地铁线虽然高度拥挤，但没有人会因此认为它当初不该被建造。 --- ### [03:30](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=210s) 承载上限、服务体验与定价机制：公交与汽车的三大核心分歧 同样的诱导机制，为何在汽车基建上显得极具威胁，而在公交基建中却被视为有益？其原因集中在运力阈值、网络规模效应以及价格调节能力三方面。 首先是基础运力上限的差异。安大略线规划的单向峰值运力为每小时 34,000 人，而同等走廊内若修建类似 DVP 的六车道高速公路，单向每小时只能承载 6,000 至 8,000 人。虽然两者都会诱导更多出行且都有饱和风险，但道路达到饱和上限的速度要快得多。 ```mermaid flowchart TD accTitle: 交通方式容量与诱导需求对比 accDescr: 对比安大略线地铁与六车道高速公路在诱导需求下的运力及饱和差异 subgraph Subway["公共交通方案（如安大略线）"] S1["诱导新客流 (Induced Ridership)"] --> S2["极高容量上限 (34,000人/小时/方向)"] S2 --> S3["不易迅速饱和，带来规模效益与增班空间"] end subgraph Highway["道路扩建方案（如DVP六车道高速）"] H1["诱导新车流 (Induced Traffic)"] --> H2["较低容量上限 (6,000-8,000人/小时/方向)"] H2 --> H3["短时间内被填满，迅速重现拥堵"] end ``` 其次，公共交通具有使用人数越多体验越好的特性。交通机构增加运力的方式通常会直接提升个体乘客的乘车品质，例如提高发车频次、改用运力更大的列车、赋予地面路口信号优先权，或者采用隧道及高架独立路权。公交乘客虽然反感挤车，但他们希望线路被充分利用；而私家车司机则完全不同，路上增添更多汽车只会造成延误和烦躁，主讲人概括道：“No one wishes for more drivers on their road to get more lanes, but you might wish for more ridership on your transit route so that you can get better frequency.”（没有人会为了能多建几条车道而希望路上有更多司机，但你可能会为了更高的发车频次而期盼自己的公交线路上有更多乘客。） 第三个差异在于定价调节机制。缓解拥堵的最直接手段是通过收费抑制非必要出行。公交系统天然内置了拥堵定价工具，可以通过调整车票或通票价格来调节需求（同时辅以低收入补贴）。然而在私家车领域，设置道路通行费或拥堵费极为罕见且极不受欢迎（至少在加拿大是如此）；上调燃油税效果有限，因为车主可以通过购买省油车型或去邻近地区加油来规避。 --- ### [05:43](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=343s) 行人与骑行基础设施：无负外部性的需求诱导 诱导需求同样普遍存在于步行与骑行设施中。如果一座城市将一条拥挤的人车混行步道宽度翻倍，为行人和骑行者划分独立通行空间，这必然会诱导更多人选择步行和骑车。这种被诱导出的需求同样是有益的：一方面，更多的体力活动能直接增进公众健康；另一方面，步行和骑行几乎不存在汽车所带来的负外部性。 大量行人和骑行者穿过社区，完全不会带来像汽车那样严重的噪音、交通安全隐患和空气污染。从空间利用和财务成本来看，骑行和步行设施造价低廉且极度节约土地。主讲人特别对比了两者的历史影响：“No neighbourhoods are being demolished to build bike lanes but lots of neighbourhoods were erased from existence to build highways in mid century North America.”（从来没有哪个社区会因为修建自行车道而被拆毁，但在 20 世纪中叶的北美，大量社区为了修建高速公路被彻底夷为平地。） --- ### [06:35](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=395s) 诱导需求不是汽车独有的特质，核心在于“你想诱导什么” 单凭“诱导需求”这一个概念，并不能成为反对扩建道路或新建高速公路的绝对论据。新汽车基建的问题本质，并不在于它会激发更多出行需求——因为一条规划合理、能便捷连接目的地的地铁、自行车道或步行街同样会激发需求。汽车基础设施的真正症结在于汽车本身的固有弊端：噪音、污染、事故伤亡等严重的负外部性，以及其在几何空间上极低的空间利用率。正是这种几何上的低效，导致哪怕给汽车分配巨量土地空间，城市道路依然极易陷入瘫痪。 主讲人总结道，诱导需求并非汽车的专属特性，它揭示的其实是一个基础交通规律：交通需求与出行模式从来都不是一成不变的，公众会根据现有的基础设施做出短期出行选择以及长期定居决策。 > “The question isn’t really which types of transportation infrastructure induce demand, because they all do; the question is which type of demand you want to induce.”（真正的问题并不在于哪种交通基础设施会诱导需求，因为它们都会；核心问题在于，你到底想要诱导哪一种需求。） 如果城市建设更宽的马路，人们就会更多地开车并围绕汽车来规划生活；如果建设快速便捷的地铁，人们就会乘地铁并围绕轨道交通来组织生活；如果修建安全舒适的自行车路网，骑行的人数就会自然增长。在视频结尾，作者幽默地呼吁大家“别忘了为自行车基础设施诱导需求并点击订阅”。 ## Notable quotes > [06:35](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=395s) The question isn’t really which types of transportation infrastructure induce demand, because they all do; the question is which type of demand you want to induce. > [03:30](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=210s) No one wishes for more drivers on their road to get more lanes, but you might wish for more ridership on your transit route so that you can get better frequency. > [05:43](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=343s) No neighbourhoods are being demolished to build bike lanes but lots of neighbourhoods were erased from existence to build highways in mid century North America. > [00:01](https://www.youtube.com/watch?v=8wlld3Z9wRc&t=1s) Subways don’t carry freight, but when it comes to carrying lots of people, mass transit wins hands down and it’s not even close. ## Mentioned Oh The Urbanity!, 当河谷园林公路 (Don Valley Parkway), 央街地铁线 (Yonge Subway Line), 安大略线 (Ontario Line), 布鲁尔-丹佛斯线 (Bloor-Danforth Line), Vox, Metrolinx ## Video description Induced demand (probably more accurately called induced traffic) is the phenomenon where building or expanding roads and highways doesn't help congestion because it results in more people driving. This is often used as an argument against building the new car infrastructure, but people don't talk often about how induced demand applies to other modes. In this video we explain why induced demand does apply to transit, walking, and cycling infrastructure, but with different consequences. Support our work/watch more: Patreon: https://www.patreon.com/ohtheurbanity Urbanism playlist: https://www.youtube.com/playlist?list=PLN3OhfIDlvuMjcg36sdLJuxaXi6OaOWFD Subscribe for more videos: https://www.youtube.com/channel/UCN5CBM1NkqDYAHgS-AbgGHA?sub_confirmation=1 More information: Visualizing the Footprint of Highways in American Cities: https://www.visualcapitalist.com/visualizing-the-footprint-of-highways-in-american-cities/ Metrolinx Ontario Line report: http://www.metrolinx.com/en/docs/pdf/board_agenda/20190912/20190912_BoardMtg_Ontario_Line_Initial_Business_Case_EN.pdf #urbanism #induceddemand #transit #toronto #ontarioline #metrolinx [Source](https://www.youtube.com/watch?v=8wlld3Z9wRc)

Source quotes

[6:35] The question isn’t really which types of transportation infrastructure induce demand, because they all do; the question is which type of demand you want to induce. [3:30] No one wishes for more drivers on their road to get more lanes, but you might wish for more ridership on your transit route so that you can get better frequency. [5:43] No neighbourhoods are being demolished to build bike lanes but lots of neighbourhoods were erased from existence to build highways in mid century North America. [0:01] Subways don’t carry freight, but when it comes to carrying lots of people, mass transit wins hands down and it’s not even close.

Source quotes

[5:43] The question isn’t really which types of transportation infrastructure induce demand, because they all do; the question is which type of demand you want to induce. [3:30] No one wishes for more drivers on their road to get more lanes, but you might wish for more ridership on your transit route so that you can get better frequency. [0:01] Subways don’t carry freight, but when it comes to carrying lots of people, mass transit wins hands down and it’s not even close.

Original transcript

[0:01] Pretty much everyone knows that public transit is more efficient than private cars at moving [0:05] large numbers of people, but we don't talk enough about just how big the difference is. [0:10] This is the Don Valley Parkway, a six-lane highway in Toronto. If you sit in one place [0:14] at rush hour and watch the DVP, you could see 6 to maybe 8,000 people in those cars [0:19] pass by in the busier direction over the course of an hour. If you do the same thing on the [0:24] nearby Yonge Subway you could see 30,000 people per direction per hour, with ongoing signal [0:29] upgrades pushing that up to 40,000 people in the future. That’s an enormous advantage [0:33] for the subway even before you consider that it only takes up two lanes, mostly underground. [0:38] Subways don’t carry freight, but when it comes to carrying lots of people, mass transit [0:42] wins hands down and it’s not even close. We're going to come back to this capacity [0:46] difference later in the video. [0:48] If you follow debates about building or expanding roads and highways you’ve probably heard [0:52] someone bring up the concept of induced demand, often linking explainer videos from places [0:56] like Vox, (where they use lots of colourful balls to explain), to argue against building [1:01] the new road or highway. Induced demand, more accurately called induced traffic, is the [1:05] idea that building new road space doesn’t solve congestion, at least in the long term, [1:09] because it encourages more driving to happen. When you build new lanes or roads, people [1:13] who previously avoided driving at rush hour start becoming less careful about when and [1:17] how much they drive. On top of that, other people and businesses see the new road capacity [1:21] and move to the area to use it. As a result, congestion eventually ends up about as bad [1:26] as before, and this is used as an argument against building the new road capacity. [1:31] Induced traffic is a very real phenomenon. It’s not infinite, you could build a big [1:35] highway in the middle of nowhere and it’s not going to become congested in the near [1:38] future, but there’s a bunch of research finding that 50 to 100% of new road capacity [1:42] in urban areas gets filled up after a few years. However, the induced traffic argument [1:46] against new car infrastructure has always seemed, maybe not wrong, but certainly incomplete, [1:51] because why does it only mention cars? What happens when we build another subway line, [1:55] for example—won’t that just become packed in a couple of years too, and isn’t that [1:58] a problem? In this video we’re going to explain why induced traffic for walking, biking, [2:02] and public transit is different than for cars, and why increased demand or usage for a mode [2:07] doesn’t have to mean slower travel for everyone. [2:09] Let’s get back to transit in Toronto. In response to overcrowding on the Yonge subway, [2:14] including at the major transfer station with the Bloor-Danforth Line, transit authorities [2:18] are planning to build a new automated subway called the Ontario Line to add capacity to [2:22] the city’s east end. When you think about it, the exact same points about induced traffic [2:26] and highways could apply here, except that we’d probably call it induced ridership. [2:30] In other words, this new subway line will cause more people to take more trips, both [2:34] people who currently live there and new people moving to east end Toronto because of the [2:38] new subway. Ridership will continue to grow and eventually at some point in the future [2:41] the Ontario Line will probably end up congested. [2:44] But if you told a transit planner that they shouldn’t build the Ontario Line because [2:48] it will just induce more ridership and eventually become congested, they would probably look [2:51] at you funny. Induced ridership is the goal of the Ontario Line, which is meant to encourage [2:56] growth in new transit-oriented communities. We want people to use the Ontario Line, whether [3:00] replacing car trips or taking trips that they otherwise wouldn’t have been able to do. [3:04] We prefer that it’s not so much new ridership that the line becomes overcrowded, that’s [3:08] bad for safety, efficiency, and user experience, but if and when that happens, it wouldn’t [3:12] mean the Ontario Line was useless and shouldn’t have been built in the first place. It would [3:16] mean the Ontario Line was really useful and we should probably build another subway line. [3:20] If that’s not possible, it’s still better to have an overcrowded Ontario Line than no [3:24] Ontario Line at all. The Yonge line is overcrowded now and no one thinks that means it shouldn’t [3:29] have been built. [3:30] If the basic principle of induced demand is the same, why does car infrastructure inducing [3:34] more car traffic seem so threatening while public transit infrastructure inducing more [3:38] transit ridership feels benign or even good? One big reason is what we mentioned at the [3:43] beginning of this video, the simple fact that public transit can carry a lot more people, [3:47] so reaching capacity is less of an immediate concern. Imagine we’re choosing between [3:51] two transportation projects in Toronto’s east end: the Ontario Line with its planned [3:56] top capacity of 34,000 passengers per hour per direction, or a six-lane highway resembling [4:01] the Don Valley Parkway with its 6 to 8,000 people per hour per direction. Both projects [4:06] will induce more people to take more trips, both have the potential to hit capacity and [4:10] become overcrowded, but one will reach capacity much faster. [4:13] It’s more than that though. It’s not just that transit can handle high volumes, it’s [4:18] that transit usually gets better with more ridership. Most of the ways that a transit [4:22] agency adds capacity to a route make service better for each individual rider, whether [4:26] that’s higher frequency, using trains over buses, giving signal priority on roads, or [4:31] making the line tunnelled or elevated. Transit riders don’t want crowding but they do have [4:35] reason to want their routes well used. Driving works differently—you want enough other [4:39] drivers to justify your road or highway existing but aside from that, traffic is really only [4:44] a threat that can slow you down or aggravate you. No one wishes for more drivers on their [4:48] road to get more lanes, but you might wish for more ridership on your transit route so [4:52] that you can get better frequency. If transit service gets better with more ridership but [4:56] the driving experience gets worse with more traffic, it makes sense that induced car traffic [5:00] feels more threatening than induced transit ridership. [5:02] There’s one more important difference between transit and driving when it comes to induced [5:06] demand, which is pricing. One simple way to reduce congestion is to charge more money, [5:11] discouraging people from making less important trips. For transit this is straightforward, [5:15] you increase the price of a fare or a pass, ideally offering a low-income subsidy if necessary. [5:20] The driving equivalent to this would be a road toll or congestion charge, but at least [5:24] in Canada we’re not set up for that—toll roads are rare and very unpopular. Increasing [5:28] the gas tax might kind of work as a substitute but people can partially get around that by [5:32] buying a more fuel-efficient car or stocking up on gas in a different jurisdiction. Thus, [5:37] another reason that induced demand is less of a problem for public transit is that it [5:40] has a simple form of congestion pricing built in. [5:43] We’ve focused on transit so far but we fully expect induced demand to apply to walking [5:47] or cycling infrastructure too. Imagine that your city has a mixed use pathway that’s [5:52] overcrowded and the local cycling advocacy group wants to double the width of the path [5:55] so that pedestrians and cyclists each have their own dedicated space. This probably will [6:00] induce more people to walk and cycle, and like with transit that doesn’t seem so bad, [6:04] whether people are replacing car trips or they’re just being more mobile in general. [6:08] Partly this is because more physical activity is a win for public health, and partly this [6:11] is because trips taken by walking and cycling lack the negative externalities of cars. A [6:16] bunch of people walking and cycling through your neighbourhood just don’t have the same [6:19] noise, safety, and pollution side-effects as the same number of people driving through [6:22] your neighbourhood. Infrastructure for walking and cycling is also relatively cheap and space-efficient. [6:28] No neighbourhoods are being demolished to build bike lanes but lots of neighbourhoods [6:31] were erased from existence to build highways in mid century North America. [6:35] Based on these examples, the concept of induced demand on its own is not actually a slam-dunk [6:40] argument against expanding roads or building new highways. The problem with new car infrastructure [6:44] isn’t only that it’ll induce more trips, because the same can be said for a new subway, [6:48] bike route, or walking path, assuming they’re built to conveniently connect people to places [6:52] they need to go. Instead, the problem with new car infrastructure is related to the specific [6:57] downsides of cars, from the negative externalities related to noise, safety, and pollution to [7:02] the basic geometric fact that they’re an inefficient way to move a lot of people in [7:05] a city, which makes them especially prone to congestion, even when we dedicate a lot [7:10] of space to them. [7:11] Rather than thinking about induced demand as a special property of cars, we should think [7:15] of induced demand as the basic fact that transportation demand and usage patterns aren’t fixed. [7:20] People make short-term choices about how to get around and long-term choices about where [7:23] to live based on the infrastructure available to them. If you build wider roads, people [7:27] will drive more and they’ll plan their lives around driving. If you build fast and convenient [7:31] transit lines, people will take transit more and plan their lives around transit. If you [7:35] build a safe and comfortable bike network that connects people to places they need to [7:38] go, people will bike more and so on. The question isn’t really which types of transportation [7:43] infrastructure induce demand, because they all do; the question is which type of demand [7:47] you want to induce. [7:49] Don’t forget to induce bicycle infrastructure demand and subscribe.