9 Synthesis

9.5 System Effectiveness

Fourteen of the systems described in this report have been formally evaluated for system effectiveness. Three have been informally evaluated, and another six have received no formal evaluation. Eight have a formal evaluation planned or underway, and twelve of the systems are in the planning/development stage or have not been activated. These proportions are shown graphically in Figure 9.

For those systems that have received a system effectiveness evaluation, formal or informal, one or more of the following measures of effectiveness were used:

Speed;
Speed reduction;

Figure 9: System Effectiveness Formal Evaluation Status for the Systems Studied

Speed distribution;
Speed variation;
Number of crashes;
Driver behavior vs. weather/road conditions;
Use of escape ramps;
Driver awareness;
Driver compliance;
Stated compliance (survey);
Positive comments (survey);
Traffic fluency;
Lane distribution;
Number of forced merges;
Shockwave severity;
Projected time to collision;
Effect on driver behavior; and,
Headways (distance and time).

Most of the evaluated systems at least partially achieved their objective(s).

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