The National Academies Press

Currently Skimming:

Pages 43-61

The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.

From page 43... ... Crossing Performance Results The evaluation of pedestrian crossing performance used the measures defined in Chapter 4: the availability of crossing opportunities in the form of yields and crossable gaps, the rate of utilization of these opportunities, pedestrian delay, and the rate of O&M interventions. The field evaluation at the CTL location generally showed that participants experienced significant delay and risk. Read the entire page →
From page 44... ... Similar to the effects above, these decreases were not statistically significant but suggest promise for the sound strips with some modifications or in combination with another treatment. This CTL crossing had the highest observed occurrence of interventions of any of the test locations, with the highest intervention rate per participant reaching 30% (six interventions in 20 crossings) Read the entire page →
From page 45... ... In the tested combination, the SS+FB treatments had a large effect on the pedestrian delay as well as a reduction in O&M interventions. Average delay and the delay over minimum were both reduced significantly, by 10–11 s, and the 85th percentile delay was reduced by over 20 s. Read the entire page →
From page 46... ... Participants in the posttests were asked several questions about the sound strips and about the push-button locator tone and audible information on the flashing beacon (Table 3) Read the entire page →
From page 47... ... Given the low yielding behavior, the pedestrian presence and treatment installation were not considered to have a notable effect on traffic operations. Single-Lane Roundabout Study Overview The scope of NCHRP Project 3-78A originally included only one single-lane roundabout site for a pretest and posttest study, consistent with other locations. Read the entire page →
From page 48... ... Table 4 shows a very low occurrence of yield opportunities at only 6.3%. The rate of encountering crossable gaps was higher, at 28.8%, which is explained by generally low traffic volumes at the site except for some peak-hour traffic surges. Read the entire page →
From page 49... ... The 85th percentile delay was somewhat higher at 19.6 s. As with other sites, individual participants experienced higher average delays, with the maximum average observed delay at 34.2 s (24.7 s delay over minimum) Read the entire page →
From page 50... ... Overall, this site appears to be the most accessible of the three tested single-lane roundabouts with low delay and risk. Participant Feedback Following each of the single-lane roundabout studies, participants were asked a series of questions about their perception of the crossing and the level of comfort in their crossing decisions. Read the entire page →
From page 51... ... Y=Yield, CG=Crossable Gap, non-CG = Non-Crossable Gap This figure shows a bar chart of all observed pedestrian–vehicle events during the RCW pretest. The graph shows a total of nine event categories, representing all combinations of event outcomes yield, crossable gap, and non-crossable gap for two conflicting lanes (near lane and far lane) Read the entire page →
From page 52... ... Y=Yield, CG=Crossable Gap, non-CG = Non-Crossable Gap This figure shows a bar chart of all observed pedestrian–vehicle events during the RCW posttest. The graph shows a total of nine event categories, representing all combinations of event outcomes yield, crossable gap, and non-crossable gap for two conflicting lanes (near lane and far lane) Read the entire page →
From page 53... ... Participants utilized only 2.0% of those events at this crossing, which represents 0.2% of all crossing events. Overall, 1.0% of events were utilized events with a non-crossable gap in one or both lanes. Read the entire page →
From page 54... ... The graph shows a total of nine event categories, representing all combinations of event outcomes yield, crossable gap, and non-crossable gap for two conflicting lanes (near lane and far lane) Read the entire page →
From page 55... ... The pedestrian delay therefore plateaus with increasing pedestrian demands, where the magnitude of this terminal delay is a function of the signal phasing. Participant Feedback Following each the pretest and posttest two-lane roundabout studies, participants were asked a series of questions about their perception of the crossing and the level of comfort in their crossing decisions. Read the entire page →
From page 56... ... As discussed in the previous sections on participant feedback, the participants' suggestions of intersection modifications after their crossings in the pretest may provide additional information about their concerns. Some suggested signals, even though some of those same individuals said that they were not fans of audible signals, and suggested that it would be good if the signal could be used optionally. Read the entire page →
From page 57... ... parable to the pretest condition as well as crossing performance at the RCW crossing. Nonetheless, the installation of the PHB is associated with some legal implications for when pedestrians should cross. Read the entire page →
From page 58... ... Given the apparent lack of understanding of the PHB, it seems that the flashing red indication of the traffic control was not intuitive to drivers. Impact on Vehicular Traffic Raised Crosswalk A pretest and posttest speed study was performed at the RCW installation to estimate the impact of the treatment installation on free-flow vehicle speeds. Read the entire page →
From page 59... ... Of the remaining sites, the two-lane roundabout crossings exhibited the highest average delay and the highest variability across participants. The two-lane roundabout delay was reduced significantly with installation of either crossing treatment (RCW and PHB) Read the entire page →
From page 60... ... The graph shows the average pedestrian delay observed for each of 12 studies as well as the standard error of that estimate. The results are discussed in the text. Read the entire page →
From page 61... ... average observed over all participants and the standard error of the estimate. The intervention comparison shows very high risk at the CTL crossings in the pretest condition along with a very high variability across participants. Read the entire page →

From page 43...

... Crossing Performance Results The evaluation of pedestrian crossing performance used the measures defined in Chapter 4: the availability of crossing opportunities in the form of yields and crossable gaps, the rate of utilization of these opportunities, pedestrian delay, and the rate of O&M interventions. The field evaluation at the CTL location generally showed that participants experienced significant delay and risk.