Our recent work evaluated the safety impact of the DFSs, via before-and-after study using Empirical Bayes (EB) method in urban areas. The results indicate that they can reduce collision frequencies by 31.0 percent to 44.9 percent for different collision severities (e.g., fatality), collision types (e.g., lane-changing), road types (e.g., collector vs. arterial) and intervention types (e.g., combining DFS with/without automated enforcement). The economic analysis found that the benefit-cost ratios if combining severe and Property-Damage-Only collisions, ranged from 8.2 to 20.2 indicating that the DFS can be an extremely economical countermeasure.The public's opinion of this countermeasure is generally positive thus encouraging municipalities with an existing system to relocate some units to optimal positions or to expand their network. This has also convinced agencies who currently do not have any DFS installed to start considering them as a low-cost yet highly effective countermeasure. However, only a few past efforts were dedicated to the problem of locating optimal sites for DFS installation. Although these studies provided preliminary insights into locating DFSs, their findings can be inconclusive owing to the fact that the safety benefits of DFSs were not taken into consideration in their location models. In particular, what are the most important location factors that need to be considered when deploying a DFS? How can we quantitatively assess the goodness of solutions generated for benchmarking the current DFS network? How can we assist cities and municipalities with planning for future expansion of their existing DFS program? These questions represent the main concern of our study.
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