Study on the number and location of measurement points for an MFD perimeter control scheme: a case study of Zurich

The goal of this paper is to evaluate the data requirements for a possible implementation of a macroscopic fundamental diagram (MFD) control scheme in an urban area. Particularly, we have studied the accuracy of MFDs created using only a percentage of the links (i.e., streets). This is especially useful because monitoring resources are often scarce, and most cities do not have access to the large amount of information that is typically associated with the construction of an MFD. We evaluated several strategies that cities typically use to place fixed monitoring devices (e.g., loop detectors), and compared them with a quasi-optimal way to choose the links. The results show that independently of the strategy used for link selection, a minimum of 25 % of network coverage, according to our accuracy methodology, ensures an average error in density ratios below 15 percentage points (ppts). Based on the particular case of the city of Zurich, we also analyzed the feasibility of implementing an MFD control scheme with the links that are currently monitored. Results are very encouraging, showing an average error below 9 ppts. Although all results were obtained with a VISSIM microsimulation model of the inner city of Zurich, we believe the knowledge and methodology presented here can be transferred to other urban areas. In fact, we are hopeful that this research can contribute to making the implementation of an MFD control scheme feasible for many cities.