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43 CHAPTER 5 Results This chapter is devoted to the results of the field trials with rate of utilization of these opportunities, pedestrian delay, blind study volunteers at the selected treatment sites. It pres- and the rate of O&M interventions. ents a summary of findings that are most pertinent to the The field evaluation at the CTL location generally showed understanding of the specific crossing challenges at the site, as that participants experienced significant delay and risk. Despite well as the effect of the installed crossing treatments. Appendix the fact that only a single lane needed to be crossed, the com- A contains more detailed results for each site, and the reader is bination of background noise at the busy intersection and encouraged to refer to that material for a more in-depth dis- high approach speeds in the turn lane caused high delays and cussion. The results are presented sequentially for channelized frequent interventions. A comparison of the two crossing loca- turn lanes, single-lane roundabouts, and two-lane round- tions in the pretest did not show significant differences for abouts. The analysis uses the analysis framework, event defini- most of the measures, giving confidence that the two loca- tions, and performance measures defined in Chapter 4. The tions allow for a valid comparison of the different treatments chapter concludes with a summary comparison of all field installed. The starting order of participants was randomized trials and some discussion items related to the results. as to which crossing they started on. No consistent and signif- icant differences were identified between crossing attempts from the curb versus from the island, although some partici- Channelized Turn Lane pants stated that crossing from the island was harder due to Study Overview the traffic noise behind them. The pretest study was completed in May 2008, and a total The field study at the CTL location focused on two crossing of 16 blind travelers participated. Fourteen of the original 16 treatments. The treatments were (1) sound strips (SS) that participants returned for the posttest study in November were intended to increase the awareness of pedestrians of 2008. The treatments were installed in early October 2008, approaching vehicles and (2) sound strips in combination allowing six weeks for driver adaptation. with a pedestrian-actuated flashing beacon (FB) that was intended to increase driver yielding behavior. In the following discussion, the crosswalks will be identified by treatments Sound-Strips-Only Treatment (SS-ONLY) installed as SS-ONLY and SS+FB, respectively. Both turn lanes Table 1 summarizes the crossing performance for the were further supplemented with lane delineators that were CTL crossing that only had sound strips and lane delineators intended to prevent late merges into the turn lane. All treat- installed. The figures were obtained by averaging the mean ments, including the lane delineators, were installed between crossing performance of each of the study participants at this pretest and posttest. A more detailed description of the site location. and treatments is given in Chapter 3. Table 1 shows that the installation of the sound strips by themselves did not have a large or significant impact on yield and CG crossing opportunities. This confirms the underlying Crossing Performance Results research hypothesis since the treatment was primarily intended The evaluation of pedestrian crossing performance used to aid with the utilization of opportunities. The probability the measures defined in Chapter 4: the availability of crossing of utilizing a yield surprisingly decreased from 50.8% to 40.5%, opportunities in the form of yields and crossable gaps, the although this difference was not statistically significant. A closer

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44 Table 1. Crossing performance summary, pretest and posttest, at SS-ONLY CTL. Performance Measure Pre Post Difference p-value Yield Opportunities 18.40% 18.60% 0.20% 0.2728 CG Opportunities 34.90% 41.20% 6.30% 0.1666 Yield Utilization 50.80% 40.50% 10.30% 0.2878 CG Utilization 60.30% 68.20% 7.90% 0.4238 Average Delay (s) 26.2 18.5 7.7 0.1898 Delay>Min (s) 15.6 11.7 3.9 0.4224 85th Percentile Delay (s) 40.9 32.7 8.2 O&M Interventions 9.40% 2.9% 6.5% 0.0204 look at the yield utilization illustrates that the percentage of due to the high ambient noise at the busy intersection. For the yield events that were forced by the pedestrian decreased from remaining 23 interventions, vehicles were moving and there- 11.3% to 6.4% (not shown in Table 1 but discussed in Appen- fore represented situations were a potential collision would dix A). A forced yield occurs when a pedestrian steps out onto have been more severe. the roadway prior to the driver initiating the yielding process. After treatment installation, only eight interventions were The degree of risk associated with these events depends on the observed for five of the 14 posttest participants. This corre- relative position and speed of the vehicle at the time of cross- sponds to a significant reduction of O&M interventions, from ing initiation. Forced yield events should therefore not neces- 9.4% to 2.9%, which is noteworthy and further establishes sarily be interpreted as poor or risky decisions. However, the that the treatment has some potential. The reduction of inter- reduction in the occurrence of forced yields (though not sig- ventions supports the hypothesis that the sound-strip treat- nificant) may suggest that the sound strips were successful ment improved the ability of the study participants to audibly in assisting the pedestrians to distinguish yielding and non- interpret the vehicle patterns in the turn lane. However, even yielding vehicles. However, this hypothesis should be confirmed an intervention rate of 2.9% remains risky, as it corresponds with additional research with this treatment. to one potentially dangerous event in 34 crossing attempts. In The SS-ONLY treatment further increased the rate of cross- the pretest condition the intervention rate corresponded to a able gap utilization by approximately 8%. However, similar risk chance of approximately one in 11 crossing attempts. to other measures, this increase was not statistically significant. The analysis does suggest that additional treatments may In general, all observed measures experienced a large degree be necessary at this location, due to a combination of high of variability across participants, making it challenging to sta- volumes, high speeds, background noise, and driver disregard tistically validate small changes in a performance measure. of crosswalk laws and pedestrians. Overall, the installation of the sound strip and lane delineator treatments at the SS-ONLY turn lane did not have a large Sound Strip plus Flashing Beacon Treatment impact on most of the availability and utilization performance (SS+FB) measures when aggregated for all participants. The treatments did seem to reduce the average and 85th percentile pedestrian Table 2 summarizes the crossing performance for the delay, as well as the delay over minimum. Similar to the effects CTL crossing that had sound strips, lane delineators, and a above, these decreases were not statistically significant but sug- pedestrian-actuated flashing beacon installed. The figures were gest promise for the sound strips with some modifications or obtained by averaging the mean crossing performance of each in combination with another treatment. of the study participants at this location. No consistent and This CTL crossing had the highest observed occurrence of significant differences were identified between crossing attempts interventions of any of the test locations, with the highest from the curb versus from the island. intervention rate per participant reaching 30% (six interven- As hypothesized, Table 2 shows that the supplemental tions in 20 crossings). The pretest intervention rate corre- installation of the flashing beacon resulted in an increase in sponded to 30 individual interventions recorded among 10 of yielding from 15.2% to 22.0%. While statistically significant, the 16 participants. Of these 30 interventions, seven were asso- the resulting posttest yielding rate of 22.0% is still considered ciated with a stopped car on top of the crosswalk. For these low. The observed yielding rate with the flashing beacon cases, vehicles were queued back from the downstream merge installed is generally within the range of findings from a national point and did not leave the crosswalk unoccupied. Participants survey of the yield performance of overhead flashing beacons seemingly were not able to hear the fact that a car was stopped at unsignalized midblock crossings (Fitzpatrick et al. 2006).