The National Academies Press

Currently Skimming:

Pages 82-96

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 82... ... Again, two were posttests after installing a raised crosswalk and a pedestrian hybrid beacon at the two studied crosswalks. The remaining three studies were performed at two single-lane roundabouts. Read the entire page →
From page 83... ... Separate delay models were developed for each of the three facility types, and guidance was provided on how the models may be applied to other sites. The extension piece further provided guidance for how microsimulation models can be used to analyze pedestrian–vehicle interaction at roundabouts and channelized turn lanes. Read the entire page →
From page 84... ... It was therefore concluded that project resources would be better spent elsewhere. However, at this particular single-lane roundabout, participants experienced relatively long pedestrian delay, probably due to the very low yielding rate by drivers and the tendency of participants to wait for long gaps before initiating crossing rather than forcing yields. Read the entire page →
From page 85... ... Treatments such as sound strips, lane delineators, and pedestrian-actuated flashing beacons cannot be expected to provide adequate accessibility at two-lane CTLs. • That the three single-lane roundabouts varied considerably in the availability and usability of crossing opportunities, delay, and risk for pedestrians. Read the entire page →
From page 86... ... The RCW significantly reduced pedestrian delay and reduced risk while not being associated with any form of red signal display like the pedestrian hybrid beacon. After RCW treatment installation, only a small percentage of drivers passed in front of the waiting pedestrian without yielding at the tested location. Read the entire page →
From page 87... ... It is hypothesized that a traffic calming treatment like the raised crosswalk or a red signal display would be more appropriate at highspeed locations. However, more research on these treatments is necessary to solidify this claim, mainly due to the observed multiple threat incidents at the RCW in the posttest. Read the entire page →
From page 88... ... readily crossed at the DAV-CLT single-lane roundabout while others experienced over 80 s of average delay. Also coming into play was the situation behind the lead vehicle. Read the entire page →
From page 89... ... is less precise, the sound of a vehicle that has just passed the crosswalk can mask the sound of an approaching vehicle, and it is often difficult to detect the presence of a yielding vehicle. The presence of multiple vehicles exacerbates all these difficulties. Read the entire page →
From page 90... ... Viability of Interventions as a Measure of Risk The accessibility framework applied in this research ultimately focuses on the concepts of pedestrian delay and risk. Pedestrian delay is reliably and objectively measured. Read the entire page →
From page 91... ... The selected safety measure of O&M interventions had been used in several prior studies involving crossings of blind pedestrians. The measure is related to the concept of traffic conflicts, which is an increasingly common safety performance measure. Read the entire page →
From page 92... ... and through traffic should be considered and studied further. The sound strips 92 Read the entire page →
From page 93... ... . The raised crosswalk design showed potential at the tested location and resulted in significantly reduced pedestrian delay and interventions; however, there is concern related to observed multiple threat conflicts, and more research is need to clarify risk. Read the entire page →
From page 94... ... way and entering the vehicular way. Also, planting strips along the sidewalk serve as a barrier that discourages pedestrian access to the roadway at places other than the crosswalk and make it less likely that a blind pedestrian will inadvertently step from the paved walkway into the paved roadway at any point other than the crosswalk or begin crossing from the wrong point without realizing the intersection is a roundabout. Read the entire page →
From page 95... ... This study and other activities will provide additional information, which in combination with results of NCHRP Project 3-78A, can give more guidance and comparisons for evaluation of treatments in other locales. But there is much more that needs to be explored in developing crossing solutions for pedestrians with vision disabilities at roundabouts and channelized turn lanes. Read the entire page →
From page 96... ... . A field-based validation of the mixed-priority delay models and work toward extending these models to data from additional sites would provide greater confidence in the modeling. Read the entire page →

From page 82...

... Again, two were posttests after installing a raised crosswalk and a pedestrian hybrid beacon at the two studied crosswalks. The remaining three studies were performed at two single-lane roundabouts.