The Modeled Network
Streets, transit, connections, and travel times as represented.
- Least-cost modeled route
- High modeled accessibility
The Core Idea
There is one modeled city, but multiple experienced cities
A map may show one best route, but that does not mean every traveler will treat it as available. A longtime resident may know the area well; a visitor may avoid it; someone traveling late at night may rule it out entirely.
One Behaviorally Available Network
The narrower set of routes a traveler will actually consider.
- Route actually considered
- Excluded from the choice set
- Familiar ground
These differences are not just personal quirks. Some come from the street itself; others come from what people have heard, learned, or experienced there. In practice, the two can be difficult to separate.
- Physical barriers
- Safety and comfort
- Familiarity and information
- Reputation and historical narrative
- Prior experience
- Perception that lags changed conditions
The same street may belong to different practical choice sets at 2 p.m. and 11 p.m.
Why This Matters
Modeled accessibility is not experienced accessibility
Accessibility measures usually begin with what appears on the map: streets, transit, travel times, and nearby destinations. But a connection that people routinely rule out may deliver less access than the model assumes.
Effectiveness of Investment
A new street, crossing, or station creates less access than expected if the people it is meant to serve routinely avoid it. Infrastructure can be built without becoming behaviorally available.
Spatial Inequality
Two people can face the same street and transit network but have different opportunities within practical reach. Familiarity, past experience, safety, and physical ability can all change the network each person is willing to use.
Planning Diagnosis
An avoided route could point to a dangerous crossing, outdated information, unfamiliarity, or a blind spot in the model. Those are different problems and do not call for the same response.
The Conceptual Backbone
Technically reachable is not the same as actually considered
The modeled network defines what is technically reachable. The behaviorally available network defines what people are actually willing to consider. The difference shapes experienced accessibility.
What narrows the second network is not idiosyncratic taste alone. Individual perception belongs here because it is systematically related to group position, prior experience, information, place, time, and mobility constraints.
A personal preference becomes more relevant to planning when the same pattern appears repeatedly across particular people or places.
A Conceptual Framework
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01
Modeled Network
Streets, transit, connections, and travel times as represented, and the modeled accessibility calculated from them.
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02
Behaviorally Available Network
The routes and places a person keeps in their practical choice set. Social and spatial conditions narrow it.
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03
Experienced Accessibility
Access as perceived, navigated, and realized in everyday life.
A possible feedback loop
- Place reputation
- Avoidance
- Underuse
- Disinvestment or changing conditions
- back to reputation
This is a hypothesis, not an established sequence. Avoidance may weaken use and investment, reinforcing the reputation that produced the avoidance in the first place.
Physical connectivity does not necessarily imply experienced connectivity.
Project Questions
Three questions this project pursues
Identify what gets excluded
Where the behaviorally available network departs from the modeled one, and whether those departures are patterned across people and places.
Measure experienced accessibility
Whether those exclusions add up to systematic differences between modeled and experienced accessibility.
Ask whether local gaps scale up
A longer-term question is whether repeated local exclusions shape broader patterns of activity and investment across the city.
From Diagnosis to Intervention
Mismatch is a diagnosis, not a policy prescription
Finding a gap is only the beginning. People may avoid a route because it is dangerous, unfamiliar, outdated in their minds, or poorly represented by the model. Each explanation points somewhere different—and sometimes toward no intervention at all.
What creates the gap, does it matter, and is there anything planners should do?
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Step 01
Identify the mismatch
The modeled network on one side; the behaviorally available network on the other.
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Step 02
Ask whether it produces a meaningful consequence
Reduced access to opportunities, additional travel burden, underuse of transportation infrastructure, or unequal experienced accessibility.
If not Intervention may not be warranted. Individual route preferences and differences in perception do not automatically constitute planning problems.
If so Ask what mechanism produces the gap, because each one points toward a different kind of response.
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Step 03
Match the response to the mechanism
Four mechanisms can produce the same observed gap, and each implies a different intervention.
Physical or environmental barrier
Perception may reflect real characteristics of the environment: difficult crossings, poor pedestrian conditions, inadequate lighting, actual safety concerns, uncomfortable transit access, or physical discontinuities in the network.
Response Change the physical environment. The goal is not to persuade people that the barrier does not exist, but to address the condition they are responding to.
Information or familiarity barrier
A route may be physically usable, but people may lack information about it or feel unfamiliar with it. Here the infrastructure itself may not need to change.
Response Wayfinding, better travel information, navigation support, and opportunities to build familiarity with alternative routes.
Persistent or outdated perception
The physical environment may have changed while people's mental maps have not yet updated. A previously unpleasant or difficult route may keep being avoided long after improvements are made.
Response Information about improvements, exposure to changed environments, and experience-based interventions that let people update their mental maps.
How quickly do mental maps respond when the physical city changes?
Routing or modeling mismatch
The problem may lie partly in how transportation models represent travel cost.
What the model weighs time + distance + monetary cost + transfers
What travelers also weigh time + distance + monetary cost + transfers + conditions the model omits
Response Incorporate perception into routing and accessibility models, which could eventually support routing systems that represent how travelers actually experience urban networks rather than assuming the objectively shortest route is behaviorally equivalent for everyone.
An Open Research Agenda
- 01Detect the gap
- 02Measure its consequences
- 03Identify its mechanism
- 04Match the intervention
- 05Evaluate whether perception and behavior change
Intervention begins with diagnosis. Perception is not automatically an error for planners to correct.
A perceived barrier may be wrong, outdated, or entirely reasonable. The existence of a gap does not tell planners which one it is.
The goal is not to make people use every route the model says they can use. It is to understand why some parts of the city fall outside people's practical choice sets, and whether planners should do anything about it.