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51 The largest pedestrian-induced vehicle delay impact was evi- pants was randomized as to which roundabout participants dent at the PS-RAL site due to a combination of high traffic crossed at first. For crossings at the two-lane roundabout, the volumes and frequent background pedestrian (student) traffic. order of which of the two crosswalks was tested first was also Background pedestrian traffic was present at all three locations randomized. but was much lower at the other two. Thus, the overall delay The pretest was completed in July 2008, and a total of 18 impact is marginal relative to vehicle delay upon entering the blind travelers participated in the study. The treatment was roundabouts. installed following the pretest, and 13 of the original 18 par- At all locations, the team would occasionally observe a deter- ticipants returned for the posttest in September 2008. mined yielding driver, who would wait 10 or more seconds to allow the pedestrian to cross, which would then cause some Raised Crosswalk vehicle delay. Any queues that formed as a result of pedestrian presence dissipated quickly once the pedestrian was out of the Figure 17 summarizes the encountered and utilized events crosswalk. In fact, buses that stopped downstream of the exit at the RCW location during the pretest. As discussed, events portion of the tested crosswalks at PS-RAL and DAV-CLT fre- are shown for the condensed matrix of near lane and far lane quently caused more significant queuing than the pedestrians. that combines the different yield types. The raw event data is contained in Appendix A. The results in Figure 17 show that a total of 686 pedestrian Two-Lane Roundabout vehicle interaction events were observed in the pretest and The field study at the two-lane roundabout location focused that 443 of these (64.5%) were non-utilized events. This sug- on two crossing treatments. The treatments were (1) an RCW gests pedestrian delay since blind pedestrians wait longer on that was intended to reduce vehicle speeds and encourage average before utilizing an opportunity. The events are further yielding behavior, and (2) a PHB, also known as a HAWK sig- divided into three vehicle states in the near lane in the categories nal. The PHB is intended to stop traffic at a red signal indica- of yield (183 events, 26.7%), crossable gap (175, 25.5%), and tion while minimizing vehicular delay because it is not a full signal, and to supply auditory information to the pedestrian via RCW-Pretest (n=686) APS. All treatments were installed between the pretest and 60.0% posttest. A more detailed description of the site and treatments Non-Utilized (n=443) is given in Chapter 3. Percent of Total Events (n= 686) 50.0% Utilized (n=243) Crossing Performance Results 40.0% The evaluation of pedestrian crossing performance used 30.0% the measures defined in Chapter 4: the availability of crossing opportunities in the form of yields and crossable gaps, the rate 20.0% of utilization of these opportunities, the 85th percentile pedes- trian delay, and the rate of O&M interventions. As discussed in 10.0% that chapter, the analysis approach for two-lane crossing was revised slightly to reflect the fact that pedestrians are faced with 0.0% two conflicting lanes. For ease of understanding, this chapter Far Lane=Y Far Lane=Y Far Lane=Y Far Lane=nonCG Far Lane=nonCG Far Lane=nonCG Far Lane=CG Far Lane=CG Far Lane=CG combines the three yield classifications (rolling, stopped, and forced) and only discusses differences where necessary. The reader is encouraged to refer to Appendix A of this report for a more detailed evaluation of the results. Concurrent with the two-lane roundabout data collection, participants also crossed at a nearby single-lane roundabout. Near Lane = Y Near Lane = CG Near Lane = non- The use of this comparison site was intended to allow for a (n=183) (n=175) CG (n=328) direct comparison between the same participants' abilities to Y=Yield, CG=Crossable Gap, non-CG = Non-Crossable Gap cross at a single-lane versus a two-lane roundabout. It further This figure shows a bar chart of all observed pedestrianvehicle events during the RCW pretest. The graph shows a total of nine event allowed the team to test for a learning effect since no treatments categories, representing all combinations of event outcomes yield, were installed at the single-lane roundabout. The results of the crossable gap, and non-crossable gap for two conflicting lanes (near lane and far lane). single-lane roundabout study were discussed above, and no such learning effect was evident. The starting order of partici- Figure 17. RCW pretest event utilization.

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52 non-crossable gap (328, 47.8%). For each near-lane category, RCW-Posttest (n=269) 60.0% the events are broken down by vehicle state in the far lane as well as by whether the particular event combination was Non-Utilized (n=62) Percent of Total Events (n= 269) utilized or not. Overall, the majority of events fell into the 50.0% Utilized (n=207) category of a non-crossable gap in both lanes, which can also be interpreted as drivers who did not yield to pedestrians. 40.0% Expectedly, almost all of these events were not utilized by the pedestrians. The figure shows that some of the event combi- 30.0% nations correspond to crossing opportunities (yield or cross- able gap) in both lanes. The utilization statistics show that 20.0% most of those opportunities involving at least one crossable gap were utilized, but that almost a third of the dual-yield 10.0% events were not. Special attention should be paid to the events with a near- 0.0% lane yield and a far-lane non-crossable gap since these are Far Lane=Y Far Lane=Y Far Lane=Y Far Lane=nonCG Far Lane=nonCG Far Lane=nonCG Far Lane=CG Far Lane=CG Far Lane=CG related to the multiple-threat condition. This event combi- nation represents 7.6% of all events, and 5.8% of these events actually were utilized by pedestrians (0.4% of all events). These potentially risky events need to be interpreted in addition to the O&M interventions that are discussed below. Overall, 1.3% of events were utilized events with a non-crossable gap Near Lane = Y Near Lane = CG Near Lane = non- in one or both lanes. (n=138) (n=80) CG (n=51) Figure 18 shows the corresponding event distribution for Y=Yield, CG=Crossable Gap, non-CG = Non-Crossable Gap the RCW posttest. It shows a reduction in the number of This figure shows a bar chart of all observed pedestrianvehicle events events encountered by the pedestrian from 686 in the pretest during the RCW posttest. The graph shows a total of nine event categories, representing all combinations of event outcomes yield, to only 269 events. Accounting for the number of participants crossable gap, and non-crossable gap for two conflicting lanes in the pretest (18) and posttest (12) studies, the resulting aver- (near lane and far lane). age number of events was reduced from 38 to only 22 events Figure 18. RCW posttest event utilization. over 16 crossing attempts per participant. Consequently, par- ticipants in the posttest had much fewer non-utilized events (62) than in the pretest (443). This points to much improved and utilizing a crossing opportunity in both lanes, PA_Dual decision-making efficiency as well as more courteous and/or and PU_Dual, as well as in only one of the lanes PA_Half and compliant driver behavior. PU_Half. By definition, the remaining events correspond to A closer look at potentially risky events shows 3.0% of non-crossable events in both lanes (PA_No and associated events that correspond to a potential multiple-threat situation utilization rate PU_No). Table 7 summarizes these statistics with a near-lane yield and a far-lane non-crossable gap. Partic- for the RCW analysis and also presents the associated delay ipants utilized 12.5% of these events, which represents 0.4% and intervention statistics as defined previously. of all crossing events. Overall, 2.6% of events were utilized Table 7 indicates that the availability of dual crossing oppor- events with a non-crossable gap in one or both lanes. This tunities increased significantly, from 56.0% to 76.9%, after suggests some potential risk at the crossing, in addition to the RCW installation. The utilization of these events was already O&M interventions discussed below. high during the pretest condition (88.3%) but increased fur- A comparison of Figure 17 and Figure 18 further shows ther to 98.1%. This rate of utilization is rather extraordinary that with the installation of the RCW, the relative percentage considering that the blind participants make crossing deci- of yield events increased, and pedestrians also encountered sions about two conflicting lanes based on auditory infor- more yields in both lanes. In return, the percentage of non- mation alone. Due to the reduction in non-crossable events crossable gap opportunities decreased, suggesting that fewer that was discussed in relation to Figure 18, the occurrences of drivers proceeded through the crosswalk without stopping. PA_Half and PA_No events both decreased. The utilization The utilization of dual crossing opportunities also increased, rates of these opportunities did not change significantly. which is surprising since no audible message was associated With more frequent and better utilized dual crossing oppor- with this particular treatment. tunities, the delay experienced by participants decreased sig- Following the discussion in Chapter 4, the nine event cat- nificantly, from 17.0 s to 8.0 s. The maximum average delay egories were converted to the probabilities of encountering experienced by a single participant also decreased, from 84.9 s

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53 Table 7. Crossing performance summary at RCW, pretest and posttest. RCW Performance Measure Pre Post Difference p-value Dual Opportunities (PA_Dual) 56.0% 76.9% 20.9% 0.0003 Single Opportunities (PA_Half) 12.5% 7.8% 4.7% 0.0842 None Opportunities (PA_No) 31.5% 15.3% 16.2% 0.0016 Dual Utilization (PU_Dual) 88.3% 98.1% 9.8% 0.0062 Single Utilization (PU_Half) 12.9% 15.2% 2.3% 0.7980 None Utilization (PU_No) 2.0% 7.6% 5.7% 0.3257 Average Delay (s) 17.0 8.0 9.0 0.0434 Delay>Min (s) 3.4 2.3 1.1 0.2117 85th Percentile Delay (s) 29.8 12.9 16.9 O&M Interventions 2.8% 0.0% 2.8% 0.0230 to 18.2 s. The delay improvements are also mirrored in the rather increased their willingness to step in front of yielding Delay>Min and 85th percentile delay statistics. vehicles. (2) Driver stopping behavior may have been altered From a crossing risk perspective, the installation of the with the RCW installation. In the pretest condition, many RCW decreased the rate of O&M interventions from 2.8% to drivers were observed to slowly coast to a stop and to approach 0%. The 2.8% pretest interventions corresponds to a risk of the crosswalk cautiously. This form of a rolling yield is difficult 1 in 36 crossing attempts. The rate further represents eight to distinguish auditorily from background noise at the round- individual observations distributed across six of the 18 par- about. In the posttest condition, driver yielding behavior ticipants. No interventions were observed for the 12 returning seemed to be more rapid. In other words, cars quickly decel- posttest participants. It is important to emphasize that four erated to a stop in proximity of the crosswalk, much like they of these 12 did experience at least one intervention in the pretest would stop at a signalized intersection or a stop sign. This mod- condition. While the reduction of interventions to 0% is statis- ified deceleration rate seemed to be more discernable auditorily, tically significant, this number in all likelihood does not repre- which presumably aids utilization. sent an absolute zero. It should therefore not be interpreted as the RCW resulting in zero risk to blind pedestrians. It is very Pedestrian Hybrid Beacon unlikely that any treatment would result in zero risk to blind pedestrians or sighted pedestrians, as evident by pedestrian Figure 19 summarizes the encountered and utilized events injuries and deaths at intersections across the country. The 0% for the PHB location in the pretest. As discussed previously, intervention rate therefore should only be interpreted as the results are shown for the condensed matrix of near-lane and fact that no interventions were observed during the 16 cross- far-lane events. The raw event data is contained in Appendix A. ing attempts by each of the 13 participants during the posttest. Figure 19 shows similar trends at this crossing to those that Overall, the installation of the RCW resulted in drastic were observed at the RCW pretest. More than half of the events improvements in crossing performance at this location, both in (325 out of 603) represent non-utilized opportunities and terms of delay and safety. It is emphasized here that these find- indicate delay. Similar to the other studied crosswalk, over 30% ings are only representative of this one crossing location. How- of events correspond to non-crossable gaps in one or more ever, the results do seem to suggest that the RCW treatment lanes, signifying drivers that did not yield to the pedestrians. shows a lot of promise at two-lane roundabout approaches. Among those events that do represent crossing opportunities Prior research (Geruschat and Hassan 2005) has linked lower in both lanes, the rate of utilization is again lowest for dual- speeds to an increased likelihood of yielding, which likely yield events. explains the effect observed here. The figure further shows that 8.1% of events are associated More surprising is that while the RCW seemingly improved with a potential multiple-threat situation with a near-lane yield the utilization of crossing opportunities, no treatment was and a far-lane non-crossable gap. Participants utilized only installed that was intended to provide more information to 2.0% of those events at this crossing, which represents 0.2% blind pedestrians. Two possible explanations are offered: of all crossing events. Overall, 1.0% of events were utilized (1) The RCW gave pedestrians increased confidence in utiliz- events with a non-crossable gap in one or both lanes. ing crossing opportunities. It therefore may not have improved Similar to the RCW, the results in Figure 20 show a reduc- the ability of pedestrians to detect opportunities (yields), but tion in events encountered by the pedestrian, from 603 to 242

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54 PHB-Pretest (n=603) PHB-POST (n=242) 60.0% 60.0% Non-Utilized (n=325) Non-Utilized (n=31) Percent of Total Events (n= 603) Percent of Total Events (n= 242) 50.0% 50.0% Utilized (n=278) Utilized (n=211) 40.0% 40.0% 30.0% 30.0% 20.0% 20.0% 10.0% 10.0% 0.0% 0.0% Far Lane=Y Far Lane=Y Far Lane=Y Far Lane=nonCG Far Lane=nonCG Far Lane=nonCG Far Lane=CG Far Lane=CG Far Lane=CG Far Lane=Y Far Lane=Y Far Lane=Y Far Lane=nonCG Far Lane=nonCG Far Lane=nonCG Far Lane=CG Far Lane=CG Far Lane=CG Near Lane = Y Near Lane = CG Near Lane = non- Near Lane = Y Near Lane = CG Near Lane = non- (n=194) (n=173) CG (n=236) (n=185) (n=40) CG (n=17) Y=Yield, CG=Crossable Gap, non-CG = Non-Crossable Gap Y=Yield, CG=Crossable Gap, non-CG = Non-Crossable Gap This figure shows a bar chart of all observed pedestrianvehicle events This figure shows a bar chart of all observed pedestrianvehicle events during the PHB pretest. The graph shows a total of nine event during the PHB posttest. The graph shows a total of nine event categories, representing all combinations of event outcomes yield, categories, representing all combinations of event outcomes yield, crossable gap, and non-crossable gap for two conflicting lanes crossable gap, and non-crossable gap for two conflicting lanes (near lane and far lane). (near lane and far lane). Figure 19. PHB pretest event utilization. Figure 20. PHB posttest event utilization. events. Again, this reduction is primarily attributable to the Table 8 shows an increased probability of encountering greatly reduced number of non-utilized events, from 325 in the dual crossing opportunities, from 55.5% to 89.3%. The rate pretest to only 31 in the posttest, signifying improved decision- of utilization of these events was high in the pretest condition making efficiency and more courteous (signal compliant) (91.6%) and was increased further in the posttest (98.3%). driver behavior with installation of the PHB. Figure 20 fur- Similar to the RCW, the rate of PA_Half and PA_No opportu- ther shows that with the installation of the PHB, most encoun- nities decreased, which is explained by fewer non-crossable gap tered events fell into the yield category, which corresponds events and generally less non-utilized events (see Figure 20). to vehicles stopping at the red signal indication. Similar to the Accordingly, the average pedestrian delay statistics improved RCW, very few non-crossable gap events were encountered in significantly with PHB installation, from 16.0 to 5.8 s. This the posttest condition. trend is mirrored in the Delay>Min and 85th percentile delay The figure also shows that 4.5% of posttest events are asso- times. The single highest average delay was 46.5 s in the pretest ciated with a potential multiple-threat situation and that par- and 14.6 s in the posttest. ticipants utilized 9.1% of these events (0.4% of all crossing The PHB also improved pedestrian safety performance and events). Overall, only 0.4% of events were utilized events that reduced interventions from 2.4% to 0%. In the pretest, seven were associated with a non-crossable gap in one or both lanes. interventions were distributed among six of the 18 participants. Following the discussion in Chapter 4, the nine event cat- Five of those six participants returned for the posttest, and egories may be converted to the probabilities of encountering no interventions were observed for them or the other seven and utilizing a crossing opportunity in both lanes, PA_Dual posttest participants. A 2.4% intervention rate corresponds and PU_Dual, as well as in only one of the lanes PA_Half and to a risk of 1 in 42 crossing attempts. Similar to the RCW, it is PU_Half. Table 8 summarizes these statistics for the PHB important to emphasize that while the reduction of interven- analysis and also presents the associated delay and intervention tions to 0% is statistically significant, this number in all likeli- statistics as defined previously. hood does not represent an absolute zero. It should therefore