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16 Somewhat dissatisfied; 3; Not satisfied at all; 1; 2% 7% Neutral; 5; 11% Somewhat satisfied; 8; 18% Very satisfied; 27; 62% FIGURE 4 Satisfaction of ATCS users with their systems. be specialists. Finally, 7% of the respondents have a limited overall signal population under their jurisdictions. Most of understanding of their systems' operations. the agencies used (although not exclusively) coordinated- actuated control before ATCSs were deployed. Handling daily In general, agencies are satisfied with their ATCSs. Eigh- and weekly fluctuations in traffic flows is the primary reason teen percent of the respondents claimed that they are very for ATCS deployments. Most of the agencies, in one way satisfied, whereas 61% are only somewhat satisfied. Figure 4 or another, considered multiple ATCSs before they decided also shows that approximately 11% of ATCS users do not see which ATCS to deploy. However, only a few of the agencies either advantages or disadvantages in using ATCSs, with went through a comprehensive process of reviewing other approximately 10% not satisfied. ATCSs. On average, an ATCS installation takes approximately 18 months, from the time funding is available to the time an ATCS becomes fully operational. Most of the ATCSs (90% SUMMARY to 95%) that were deployed during the last 20 years are still operational. Although the agencies reported various factors This chapter presented the operational backgrounds of ATCS that prevented them from expanding their ATCSs, most of deployments and the institutional capacities of the agencies the agencies (70%) have expanded their systems since the that deploy ATCSs. In general, agencies deploy ATCSs in initial installation. In general, most of the agencies (79%) are operational environments where ATCSs are known to pro- satisfied with operations of their ATCSs. The next chapter vide the best performance. For most of the agencies, traffic describes the working principles of ten major ATCSs used signals under an ATCS contribute from 10% to 30% of the throughout the world.