Urban simulation for the rest of us
Since time immemorial, urban futures have been imagined by kings and generals, and later by industrialists. Today, governments, developers, and other institutions can commission complex simulations of the futures they propose. The people who live with the consequences may be invited to comment, while having few comparable means to test the assumptions or demonstrate an alternative.
Whathappensify is urban simulation for the rest of us, created to democratize the power to shape the future of the places we live. To "simulate back" is to answer an analysis with one of your own, or develop an idea before anyone has commissioned a study. People should be able to bring proposals into public life in a form others can examine, compare, and improve.
A simulation presented in a planning process is an argument about the future. Its authors have chosen the questions, assumptions, and consequences to examine. Those choices can influence which options an institution regards as viable and which tradeoffs it treats as acceptable. A resident responding to a million-dollar model may have a right to be heard while lacking comparable means to develop and test a proposal. Whathappensify aims to make that practical capacity more widely available.
Whathappensify is being developed as digital public infrastructure for cities: a shared capacity to explore proposed changes, compare alternatives, and examine the evidence behind a conclusion. Visual controls and AI assistance make that capacity accessible to people who do not write simulation code. The aim is to support people developing ideas together, with the same underlying capability also available to entrepreneurs, scientists, and engineers.
A city proposes to raise a road
Consider a city proposing to raise a road so that people can reach a hospital during flooding. Residents living beside the road need to understand how the proposal might affect exposure around their homes. They may have an alternative design. A what-if would compare the existing conditions, the city's proposal, and the residents' alternative, making the assumptions and limits of each comparison available for examination.
In Whathappensify, that what-if begins with a question. An AI assistant can help identify relevant data and formulate a proposed scenario: the place, the change being considered, the conditions to represent, and the consequences to examine. You review and approve the scenario before the simulation runs. You can inspect the results through maps, visual playback, and numerical comparisons, then revise an assumption or develop another alternative. Direct controls and AI assistance operate on the same what-if, so the work remains available when you return to it.
The answer includes a record of the data, methods, and assumptions used. The platform distinguishes a computed result under stated conditions from a claim supported by observations of the world. When a requested operation lacks the evidence or inputs it requires, the platform states the limitation. An AI assistant's fluent explanation can be checked against the recorded computation. Researchers and domain experts remain necessary to evaluate whether a method represents the relevant conditions adequately.
Participants can respond to an analysis in several ways. They can reproduce a calculation when they have access to its inputs, examine the result through different priorities, change an assumption and compare alternatives, or contribute evidence that was missing. Each response retains its relationship to the work being examined. People can develop a proposal privately, share it with selected collaborators, or publish work they are authorized to share.
People may agree about a calculation and disagree about what the result means for a decision. A shorter journey to a hospital and increased flood exposure around homes concern different people and different obligations. Participants can propose criteria for judging a design, explain the tradeoffs they consider acceptable, and question the criteria proposed by others. Whathappensify records these perspectives in optional Frames: explicit accounts of whose concerns are being considered, how those concerns relate to available measures, and what the measures leave out. A concern can remain in the record even when it cannot responsibly be reduced to a number. Participants retain responsibility for judging acceptable tradeoffs.
Who gets to put a proposal forward
A city can take public engagement seriously while organizing it through a centralized process. Residents submit comments; officials review and summarize the contributions, then explain how those contributions affected a proposal. That process can be open and responsive while the work of developing designs, selecting measures, and interpreting what people said remains concentrated within the institution.
Whathappensify is intended to support co-creation in which many participants can develop and exchange proposals. Residents could work with planners, researchers, local businesses, and one another to test different designs and examine them through different priorities. Someone could revise another participant's design, contribute local evidence, or propose a different account of which tradeoffs are acceptable. The original proposals, responses, and reasons would remain available for others to examine, with their authorship preserved.
Participation could begin before an institution defines a project and continue while designs remain open to change. A community's local knowledge could influence the questions being asked, the options being developed, and the criteria used to assess them. Public bodies would gain a wider range of proposals to consider, while participants could respond directly to one another's work. Accountable institutions would still need to explain their decisions, including which alternatives they considered and how they addressed unresolved disagreement.
Someone has to maintain it
Realizing that purpose at scale requires a maintained public capability. People need reliable access to usable tools, relevant data, and assistance. Institutions need arrangements for maintaining methods, evaluating results, and carrying work forward when staff or contractors change. Developers need interfaces they can build on with reasonable confidence that access will continue. These requirements explain why Whathappensify is being developed as public infrastructure.
Its civic purpose provides a reason for collective investment. Cities, universities, foundations, and civic organizations have a reason to support a capability that residents and small organizations could not each finance independently. That support can cover shared data preparation, evaluation of methods, accessible applications, and participation by people with limited resources. Public access and accountability are the defining commitments. Operation could be municipal, nonprofit, university-based, or distributed among organizations under shared rules.
Accountability includes the ability to examine the infrastructure itself. Participants need to know which methods were used, inspect assumptions, and compare alternative methods where suitable ones exist. Residents must remain able to question a proposal from an institution that supports the infrastructure. Governance must also address access, privacy, correction, and the distribution of resources. Public trust will depend on how these commitments work in practice.
The work that comes before an idea is tested
Shared provision changes the conditions under which innovation becomes possible. Preparing local data, connecting appropriate models, and establishing repeatable experiments can require substantial work before an idea is tested. A maintained common capability allows more of that preparation to be reused. Small organizations and independent researchers can then spend more of their effort on the question they are exploring. Predictable access gives developers a basis for investing in applications that serve particular professions and communities.
A founder developing a delivery service might compare operating areas and schedules, examine how many journeys different arrangements would require, and explore effects on traffic and curb use. A public agency might examine a proposed cooling intervention or a new transport service. The aim is to shorten the time between an initial idea and a justified trial in the world. Some ideas will be revised or abandoned before significant commitments are made. More people with practical knowledge of a place could test possibilities that an established institution would never have considered.
Researchers can use the same infrastructure to explore technologies and processes whose effects depend on real places. They can compare methods under explicit conditions, retain unsuccessful results, and evaluate predictions against later observations. A flood intervention, for example, can be studied in relation to transport and access to services, with the connections between models subject to evaluation. The project aims to accelerate scientific and technological progress by reducing repeated preparation and making experiments easier to reproduce, challenge, and extend. Those advances could contribute to more resilient infrastructure, improved accessibility, and reduced exposure to environmental hazards.
The architecture supports applications built for different purposes. Developers can use the software development kit to build specialized tools, while AI assistants use the more constrained Model Context Protocol interface. The shared infrastructure supplies computational capabilities and what-if records; application builders determine how people encounter and use them. A community planning tool, an application for a local trade, and a research workflow can therefore use common capabilities while providing different experiences.
Innovation can also contribute to the public infrastructure. Researchers can contribute evaluated methods. Developers can build applications that make a capability useful to another group of people. Repeated what-ifs can identify missing data and errors, and commercial activity can help finance maintenance where operating arrangements direct revenue to that purpose. Those contributions require clear terms and sustained stewardship. The organizations responsible for the infrastructure must preserve its public commitments as demand grows.
A city need not collect everything first
A useful simulation capability can also provide a starting point for developing shared urban data resources. A what-if establishes which data are needed, what quality the analysis requires, and who benefits from maintaining them. A recurring question about access to a clinic, for example, creates a specific reason to improve information about streets, crossings, and barriers to movement. With permission, the preparation can support later what-ifs by other communities, service providers, and researchers.
Repeated what-ifs provide a basis for developing a data commons around demonstrated needs. Each what-if still requires suitable data and methods, but a comprehensive collection of city data need not precede every useful application. Participants can establish rules for contribution, access, correction, and maintenance as shared uses develop. Alongside shared datasets, they can maintain reusable scenarios, methods, and validation records. Contributors improve those resources by resolving errors and extending the evidence about where the methods work. Private what-ifs and restricted data retain their access conditions.
The civic and innovation purposes are interdependent. A public commitment provides a reason to maintain broad access and invest in work that individual customers may not support. That common provision gives more people the means to develop ideas, build applications, and conduct research. Their contributions can improve the shared capability, provided its stewards maintain the conditions under which public benefit is possible.
What we are building
Progress must be examined in the places and decisions where people use the platform. Evidence would include proposals originated by people with limited access to commissioned analysis, revisions developed through collaboration, and decisions that reflect participants' stated concerns. Researchers and developers should be able to reuse and evaluate one another's work. Participants should help assess whether tested changes improve conditions in their lives and determine whose experience needs attention. Funding must support the time, skills, local relationships, and continuing maintenance through which technical access becomes usable capacity.
Whathappensify is currently a working prototype in development, with no public sign-up. Establishing reliable public provision requires further work on the product, evaluation against real-world observations, and the institutional arrangements for access and stewardship. The project seeks civic, research, development, and philanthropic partnerships to establish that capacity and assess what difference it makes.
The technical material that follows describes how the platform records evidence, constrains AI operations, preserves human approval, and connects computation to what-ifs that can be inspected and revised. These design choices serve the public purpose: giving more people the practical capacity to develop ideas, examine consequences, and participate in shaping the places where they live.