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OCR for page 115
115 Exhibit 22. O&M interventions by subject and Exhibit 23. Crossing performance by time of day. summary pre and post at single-lane roundabout. Single-Lane Roundabout Performance Measure Pre Post 20.0% Yield Availability 40.4% 43.8% PRE Gap Availability 23.5% 21.3% 15.0% POST Yield Utilization 79.4% 84.7% O&M Interventions Gap Utilization 85.1% 81.2% 10.0% 85th percentile Delay (s) 22.2 21.7 O&M interventions 1.4% 0.5% 5.0% 0.0% behavior or traffic volumes. The crossing opportunity avail- 1 3 6 9 11 16 4 7 10 12 14 17 2 5 8 13 15 18 ability measures, P(CG_ENC) and P(Y_ENC), remained un- -5.0% 9:00am 11:30am 3:30pm changed, as did the rate of utilization of these opportunities. The analysis of the delay performance of study participants Subject showed no conclusive pre and post difference. The number of experimenter interventions appeared to have dropped from of a risky decision at the rates 0.5% and 1.4% are 18.2% and four in the pre to only one intervention in the post; however, 43.1%, respectively. After 100 crossings, the entry intervention due to the low sample size and rare occurrence of this mea- rate of 2.8% in the pre condition results in a 94.2% likelihood sure, this effect is believed to be due to random variability. of a risky decision. Exhibit 23 summarizes the crossing performance for the Golden single-lane roundabout. In a comparison to other single-lane roundabouts, the Golden, CO, Single-Lane Golden roundabout showed a higher rate of driver yielding Roundabout Summary and a comparable rate of crossable gap occurrence. The rate of The field evaluation at the single-lane roundabout in Golden opportunity utilization was in the same general range as other did not provide statistical evidence of a learning effect by sites. For all compared sites, the between-subject variability the blind study participants or significant changes in driver was very large.