The safety in numbers (SiN) effect is often invoked as a mechanism by which increasing
numbers of vulnerable road users introduced into a transport network can result in
reduced per-capita risk of collision resulting in injury or death. Mechanisms underlying
SiN’s function, however, have not been well described. Extending previous agent-based
modelling work, this study explored the potential role of behavioural adaptation of drivers
to the presence of cyclists that followed patterns of Rescorla–Wagner (R–W) learning mod
els. Results indicated that SiN effects consistent with those present in real-world studies
were replicable in a simulated environment, and that R–W model input settings were able
to control the strength of the SiN effect in combination with the influence of increased
cyclist density. The combined theoretical and simulation model presented here provides
a novel means by which the potential safety effects of cycling policy settings and interven
tions may be academically and practically explored.