Win-win approach to designing cities for cars and pedestrians

Designing modern cities often means navigating a delicate trade-off: the more space allocated to cars, the less there is for pedestrians, green areas, and public spaces. But what if urban planners didn’t have to choose? New research from the Singapore University of Technology and Design (SUTD) suggests that walkable neighbourhoods and road accessibility can coexist—thanks to generative urban modelling.

Rethinking urban planning: from trade-offs to synergies

For decades, urban planners have grappled with the challenge of creating cities that serve both pedestrians and vehicles. Traditional approaches often assume that improving pedestrian networks—such as footpaths, crossings, and walkable blocks—must come at the expense of road infrastructure.

SUTD’s recent study, Generative urban modelling for walkable neighbourhoods: design optimisation for pedestrian-oriented street networks, challenges this long-held assumption. By leveraging generative urban models—computational tools that simulate and optimise thousands of potential layouts—researchers demonstrated that cities can achieve a balance between mobility and liveability.

What Is a generative urban model?

Generative urban modelling uses advanced algorithms to:

Simulate thousands of urban design scenarios.
Evaluate layouts against multiple performance criteria (e.g., accessibility, connectivity, environmental impact).
Identify optimal or near-optimal solutions faster than traditional planning methods.

Unlike conventional urban design, which often merges car and pedestrian networks into a single framework, SUTD’s model generates and assesses them separately. This allows planners to explore the complex interactions between road systems, pedestrian routes, crosswalks, and junctions—without assuming one must be sacrificed for the other.

Testing the model in Singapore

The research team applied their model to a 100-hectare test site in Singapore. Over 3,000 design variations were generated, each evaluated on key criteria such as:

Street reachability for both cars and pedestrians.
Walking distances to points of interest.
Number of crosswalks and intersections.
Construction and maintenance efficiency.

Two main scenarios were tested:

Resource-efficient design: Prioritised reducing land use and construction needs, often overlapping pedestrian and vehicular networks.
Pedestrian-oriented design: Focused on improving walking comfort, safety, and connectivity, with more direct footpaths and fewer crosswalks.

The results revealed that many layouts supported both road access and walkability—a finding that disrupts the conventional belief in inevitable trade-offs.

Key findings: walkability and road access are not mutually exclusive

The study highlighted several important insights for the future of sustainable urban design:

Pedestrian and vehicular networks can be complementary. Roads often improve walkability when they include pavements, while excessive crosswalks or intersections can slow pedestrians.
Direct pedestrian routes matter. Neighbourhoods with reduced crosswalks and well-separated footpaths provide safer and more pleasant walking environments.
Trade-offs are explicit, not hidden. Increasing pedestrian networks boosts walkability but consumes land; reducing roads helps pedestrians but increases driving distances. The model allows planners to weigh these trade-offs transparently.
Generative design supports evidence-based planning. By simulating thousands of outcomes in minutes, the tool equips planners with a data-driven foundation for decision-making.

Implications for future city design

In dense, land-scarce cities like Singapore, the ability to balance mobility, sustainability, and liveability is crucial. Pedestrian-oriented designs not only support healthier, more active lifestyles but also contribute to environmental and social goals, such as:

Lower reliance on private vehicles.
Reduced air and noise pollution.
Improved public well-being and inclusivity.
More resilient, adaptable neighbourhoods.

The SUTD researchers envision expanding the model to include factors such as:

Thermal comfort in hot climates.
Access to amenities and services.
Inclusive design for people with disabilities.

They also see Design AI—the collaboration between artificial intelligence and human expertise—becoming a cornerstone of urban planning.

Toward smarter, more liveable cities

The SUTD study demonstrates that walkability and road accessibility are not a zero-sum game. By using generative urban models, planners can identify design solutions that enhance both pedestrian experience and vehicular access.

As cities worldwide confront the challenges of climate change, rapid urbanisation, and increasing population density, tools like these will be essential. They empower planners to design neighbourhoods that are efficient, inclusive, and sustainable—making urban spaces more liveable for everyone.

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