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47 Table 3. Participant responses to treatment effectiveness at CTL. Average of responses (N=13) 1=strongly disagree, 5=strongly Rating questions agree The sound strips helped me know when vehicles were approaching. 4.38 The sound strips helped me know when vehicles were slowing down. 3.54 The sound strips helped me know when vehicles had yielded. 2.92 The sound strips made me confident that I was starting to cross at a safe time. 3.46 Where there were beacons installed, I'd push the button each time I wanted 4.08 to cross. Knowing the beacon was flashing made me more confident that I was 3.83 starting to cross at a safe time. The speech message didn't interfere with my ability to hear traffic. 4.33 The locator tone on the beacon helped me know I was coming to the 3.77 crosswalk. The locator tone helped me go straight across the crosswalk. 2.64 The locator tone helped me know I was approaching the end of the crosswalk. 2.83 that may have formed at the main intersection. Consequently, Single-Lane Roundabout the average CTL vehicle delay (in the absence of pedestrians) was low compared to other movements, and drivers expected Study Overview largely free-flowing operations. The scope of NCHRP Project 3-78A originally included The observed vehicle free-flow speeds in the pretest con- only one single-lane roundabout site for a pretest and posttest dition were high at both CTL locations, with an average study, consistent with other locations. However, following the 32.8 mph upon entering the turn lane and 21.5 mph as vehi- pretest, the research team was directed not to pursue with cles crossed the plane of the crosswalk, determined from laser treatment installation and a posttest at the site. The site was speed measurements. The crosswalk speeds were lower during not considered suitable for treatment installation due to par- signal phases that resulted in traffic moving downstream of ticipant responses, low intervention rate, and low traffic vol- the CTL (opposing left-turn and cross-street through phases). umes during the pretesting. Consequently, the research funds During those phases, average free-flow speeds at the cross- were reallocated to revisit available video data collected at a walk were 18.5 mph, while the average during other phases single-lane roundabout in Raleigh, NC, and to study an addi- was 22.4 mph (p < 0.0001). This difference points to the fact tional single-lane roundabout in Golden, CO. The prior data that drivers are well aware of downstream traffic conditions. collection at the Raleigh site was comparable to the NCHRP This behavior further causes concerns regarding driver atten- Project 3-78A studies since the same general data collection tiveness to pedestrians at the crosswalk since the distance protocol was used. The Golden site was selected for supple- between the back of the crosswalk and the downstream merge point is only approximately 50 ft. It is one possible explana- mental study due to its proximity to the studied two-lane tion for the low observed yielding rate at this site. roundabout. The site was studied twice (concurrent with the With the installation of the sound strip and flashing beacon two-lane roundabout pretest and posttest), yet no treatments treatments, no significant effects on speeds were detected in were installed. This approach served two objectives: (1) the most segments of the turn lanes. A slight increase in speeds was ability to compare the crossing ability of the same participants measured just upstream of the crosswalk (increase from 21.5 to at a single-lane and two-lane roundabout, and (2) to test for a 22.5 mph, p = 0.0536), but this change is not considered to be a learning effect of the same participants repeating the study notable impact on driver behavior. Generally, no large queuing without any treatment installation. impacts were detected as a result of drivers yielding to pedestri- This section presents the crossing performance results ans. In some cases, queues from the downstream merge point sequentially for all three locations. It then discusses the impact spilled back across the crosswalk in both pretest and posttest on vehicle traffic and a summary of participant survey responses conditions, resulting in a few crossing attempts in between concurrently for all three locations. stopped cars. In several instances, participants were not aware The Charlotte, NC, single-lane roundabout (DAV-CLT) of a stopped vehicle on the crosswalk, resulting in O&M inter- was studied in the fall of 2007, and data from a total of 10 blind ventions as discussed above. Given the low yielding behavior, participants were used in the analysis. Even though there were the pedestrian presence and treatment installation were not a total of 19 participants in the study, the remaining data were considered to have a notable effect on traffic operations. not available for analysis due to video malfunction. For the