Fig. 1

A visualization and example of the modified first step of the MH3SFCA method. Originating from the population location \(i\), the probability of interaction \(Huff_{ij}\) is calculated for the three pairings with the supply locations \(j_{1}\), \(j_{2}\) and \(j_{3}\). The supply locations are located within the travel time catchment (\(d_{max} = 10\)) of \(i\). The coefficient of friction is calculated for the chosen \(d_{max}\) by rearranging the Gaussian function \(f\left( d \right) = e^{{\frac{{ - d^{2} }}{\beta }}}\)