All the networks were originally constructed in a flat 2D plane. Over the majority of Christchurch, this generalisation is not unrealistic. However in the Port Hills, errors between the slope distance and the 2-D plan distance begin to appear. To overcome this error, the network edge length should be set to the slope distance to improve the accuracy of the models.
Due to time constraints the effect of gradient on network traversal speed was only incorporated into the non-motorised networks (walking and cycling) where this effect would have the greatest impact.
All the above networks have been created based on time. The use of cost, either real or perceived are variables that would be useful for testing including public transport fares, penalties for public transport interchange and car parking charges.