Supply curves for urban road networks

Supply curves are essential for demand prediction in aggregate networks, an d need to relate cost of use to flow demanded rather than to flow performed . The paper defines the parameters of relevance and the relationships requi red. A microsimulation model is used to generate such relationships for hyp othetical networks. Network performance curves can exhibit backward-bending relationships between speed and flow performed, but these curves are inapp ropriatefor demand prediction. Relationships between speed and flow demande d are monotonic, but not necessarily linear. They can exhibit spatial and t emporal dependencies, both of which requires them to be reestimated if dema nd patterns change.