George Brown College: Slime Mould Campus Circulation — B+H Architects / Raphael Kay (Harvard)

Biological model: Physarum polycephalum (slime mould)

Company: B+H Architects / Raphael Kay (Harvard)

A campus master plan for George Brown College in Toronto that uses slime mould algorithms to optimise transportation routes between multiple urban campus patches, revealing resilient redundancies in the network.

The challenge

Multi-site urban campuses face complex circulation challenges where conventional traffic planning optimises for shortest distance but ignores resilience, creating networks that collapse when a single route is disrupted—a critical issue in congested cities like Toronto.

Nature's strategy

Physarum polycephalum (slime mould) forms tubular networks between food sources that optimise for both transport efficiency and network resilience. The organism naturally creates redundant pathways that maintain connectivity even when individual links fail.

What was emulated

Decentralised network formation; efficiency-resilience trade-off optimisation; redundant pathway creation; adaptive resource transport through tubular networks that thicken with use and thin with disuse.

The innovation

Using live slime mould and genetic algorithms to map optimal campus circulation routes that balance efficiency with redundancy, then layering indigenous cultural mapping to create transportation networks that serve educational, cultural, and reconciliation purposes.

Full case study

George Brown College presents a unique urban campus challenge: its facilities are broken up into multiple patches distributed throughout Toronto. As part of the circulation and transportation strategy for their campus master plan, B+H partnered with Harvard University student Raphael Kay to use Physarum polycephalum—slime mould—to discover more efficient and resilient transportation routes between campus locations. The approach builds on the famous Tokyo rail experiment where slime mould replicated the efficiency of the city's railway network. Food sources representing each campus location (Mount Dennis West, Casa Loma, DT District South) were placed in a petri dish, and the slime mould's network-forming behaviour revealed optimal connections. The beautiful insight was not just efficiency but resilience: the slime mould taught the team about building redundancies into the network. Toronto's notoriously congested traffic means that when one road is blocked, the entire system can fail. The slime mould network naturally creates backup pathways. The team also layered indigenous reconciliation mapping onto the transportation network, exploring how educational routes could connect indigenous historical areas in terms of both culture and farming, ensuring that road infrastructure and transportation serve future indigenous reconciliation opportunities.