Click for next page ( 37


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 36
36 Flashing Amber Beacons Characteristics Overhead flashing amber beacons are mounted on mast arms that extend over the roadway at or in advance of the crossing location. Flashing amber beacons can also be mounted on signposts at the roadside. The flashing beacons can be activated by either a pushbutton or a passive detection technology, such as bollards, video, or microwave sensors. Continuously flashing beacons are not included in this category; they are included in the enhanced and/or high-visibility category. This traffic control device is subject to requirements specified in the MUTCD. Pedestrian Crossing Flags Characteristics Pedestrian crossing flags are square flags (of various colors, typically orange, yellow, or fluorescent yellow-green) mounted to a stick that is held by pedestrians waiting to cross or while crossing the street. The flags are typically stored in sign-mounted holders on both sides of the street at crossing locations. This is an experimental device not currently included in the MUTCD. Figure 13. "Active When Present" devices. The staged pedestrian approached the crossing, activated the island curb line (or inside lane line) before crossing the the crossing treatment (where applicable), and stood fac- second direction of traffic. ing oncoming traffic within 1 ft (0.3 m) of the curb line Staged pedestrians aborted the crossing attempt after 1 (even when parking or bike lanes are present). Where no minute if no vehicles stopped or yielded. curb was present, the staged pedestrian stood within 1 ft A second research team member and a video recording (0.3 m) of the outside edge of the curb lane. device were always present but inconspicuous to motorists The staged pedestrian could approach the crossing at any during the staged pedestrian tests. time when vehicles were within sight distance of the crossing. Vehicles that were too close to comfortably stop--estimated as being inside the stopping sight dis- tance per AASHTO Green Book--were not counted in the Collection Approaches test (56). To obtain the general population and staged pedestrian Staged pedestrians avoided attempting to cross while other data, the following data collection approaches were used: pedestrians were attempting to cross. Motorists who did not stop were counted as not comply- Videocameras were used to provide a permanent record of ing. Motorists who slowed down without passing through the crosswalk to permit the staged pedestrian to safely cross pedestrian and motorist behavior. Palmtop computers were used on site to record certain were considered yielding vehicles. For multi-lane approaches, the staged pedestrian took one aspects of pedestrian and motorist behavior. or two steps into the street if the curb lane motorist Site condition sheets were used to document geometric stopped/yielded but a motorist in the inside lane was still characteristics of each site. approaching. For divided roadways with a median refuge island, the The specific protocol for each of these activities is described staged pedestrian paused as necessary within 1 ft (0.3 m) of in more detail in the following sections.

OCR for page 36
37 In-Street Pedestrian Crossing Signs Characteristics In-street crossing signs are regulatory signs placed in the street (on lane edge lines and road centerlines, or in medians) to remind road users of laws regarding right-of-way at an unsignalized pedestrian crossing. This traffic control device is subject to requirements specified in the MUTCD. R1-6 R1-6a High-Visibility Signs and Markings Characteristics High-visibility signs and markings are warning devices placed at or in advance of the pedestrian crossing. These include fluorescent-yellow-green pedestrian crossing signs, other pedestrian crossing signs, high-visibility crosswalk markings, and other devices that attempt to draw attention to the pedestrian crossing. Many of these high-visibility signs and markings are included in the MUTCD and are subject to requirements specified in the MUTCD. Median Refuge Islands Characteristics Median refuge islands are a design treatment that permits pedestrians to cross one direction of street traffic at a time. Median refuge islands are typically raised above the roadway surface with an accessible pedestrian path, typically offset to direct the view of crossing pedestrians at the second direction of street traffic. Two-way left-turn lanes and other median treatments that vehicles routinely enter are not considered appropriate refuge for pedestrians. Curb extensions, roadway narrowing, raised crosswalks, and other design treatments or traffic- calming elements can also be used to improve the safety of unsignalized pedestrian crossings. Figure 14. "Enhanced and/or High-Visibility" devices. Video Data Collection Approach 9 Originally the research team intended to collect the neces- 6 sary data by videotaping the crossing movements at the vari- ous study sites. Using video data would provide a record of 2 the events that took place during the study period. In the data 6 reduction process, it was possible to review these events 10 numerous times to consistently interpret and record needed 7 information about pedestrian crossing events. 2 The video recording of pedestrian activities primarily used one of TTI's two camera trailers, which can raise a camera 30 ft (9 m) in the air to record a bird's-eye view of the study area. The video trailer is normally outfitted with a single videocas- Figure 15. Location and number of study sites. sette recorder (VCR) and a monitor, along with a hydraulic

OCR for page 36
38 Table 17. Study sites and their characteristics. Site Number Speed Limit Distance to Distance to Transit (ft) Treatment Width (ft) Signal (ft) Extension Midblock Sidewalk Sidewalk Curb (ft) Crossing Parking Curb to Median Bicycle Lanes Curb Lane Lane Near Far AZ-TU-1 Hawk 40 6 20.00 100.17 N N N Y Y 45 1600 N AZ-TU-2 Hawk 35 6 20.00 103.50 N Y N Y Y 105 1255 N AZ-TU-3 Hawk 35 6 20.00 100.50 N Y N Y Y 125 1225 N AZ-TU-4 Hawk 35 4 13.00 72.00 N Y N Y Y 0 975 N AZ-TU-5 Hawk 35 4 12.00 63.75 N N N Y N 108 1274 N AZ-TU-6 HiVi 35 4 20.00 72.50 N N N Y Y 123 1280 N AZ-TU-7 HiVi 25 4 12.00 57.33 N N N Y Y 69 197 Y CA-LA-1 OfPa 35 4 11.00 75.00 Y N N Y Y 20 562 N CA-LA-2 OfPa 35 4 11.00 83.00 Y N N Y Y 325 684 N CA-LA-3 OfPa 30 2 12.50 60.50 Y N N Y Y 285 350 N CA-LA-4 Msig 25 4 10.00 70.00 Y N N Y Y 250 320 Y CA-LA-5 Msig 25 5 0.00 57.00 Y N N Y Y 90 295 Y CA-LA-6 Msig 35 4 0.00 60.00 Y N Y Y Y 200 360 Y CA-LA-7 Msig NP 4 10.00 80.00 N N N Y Y 60 850 Y CA-LA-8 OfPa 35 4 10.00 60.00 N N N Y Y 55 720 N CA-SM-2 Refu 30 4 6.00 66.00 Y N N Y Y >2600 420 N CA-SM-3 Refu 30 4 16.00 76.00 Y N N Y Y 20 370 N MD-P1 Refu 35 6 22.00 92.00 N N N Y Y 0 500 Y MD-TO-1 OfPb 35 4 0.00 46.00 N N N Y Y 400 950 N OR-PO-1 Refu 35 4 8.50 60.67 N Y Y Y Y 188 675 N OR-PO-2 Half 35 4 12.00 77.00 Y Y N Y Y 153 500 N OR-PO-3 Half 35 4 0.00 50.00 N N N Y Y 0 535 N OR-PO-4 Half 35 4 0.00 51.00 Y N N Y Y 0 780 N OR-PO-5 Refu 25 2 10.00 44.00 N N Y Y Y 0 785 N OR-PO-6 Refu 35 4 9.00 75.50 Y Y Y Y Y 110 1000 N TX-AU-1 HiVi 35 4 10.00 50.00 N N N Y Y 185 190 N TX-CS-1 Refu 35 4 10.00 54.50 N N N Y Y 1056 530 Y UT-SL-1 Flag 30 6 5.50 96.83 Y N Y Y Y 0 242 N UT-SL-2 OfPb 30 4 0.00 54.00 N N N Y Y 208 360 N UT-SL-3 OfPb 35 4 0.00 70.00 N N N Y Y 2600 800 N UT-SL-4 OfPb 35 4 0.00 56.75 N N N Y Y 0 1848 N UT-SL-5 Flag 35 4 9.08 68.00 N N N Y Y 71.5 1320 N UT-SL-6 Flag 30 4 12.33 83.33 Y N Y Y Y 600 600 N WA-KI-1 Flag 35 2 11.42 57.92 Y Y N Y Y 50 2640 N WA-KI-2 Flag 30 4 0.00 60.00 Y N Y Y Y 2600 215 N WA-KI-3 Flag 25 2 0.00 45.00 Y N Y Y Y 97 473 N WA-RD-1 InSt 25 2 0.00 38.25 N N N Y N >2600 2700 Y WA-RD-2 InSt 30 3 8.00 49.50 N N N Y N 2600 439 N WA-RD-3 InSt 30 2 10.50 43.50 N N N Y Y 234 345 N WA-SE-1 Half 35 4 0.00 54.50 Y N N Y Y 61 447 N WA-SE-2 Half NP 2 12.00 54.00 Y Y N Y Y 104 534 N WA-SE-3 Half 35 4 0.00 42.00 N N N Y Y 123 291 N lift system on the roof of the trailer that raises an attached obtain an unobstructed view of the entire crossing and videocamera. For this project, a second VCR and camera were approaches. In these instances, supplemental battery-powered added to the trailer. One camera provided a wide-angle view camcorders were used in conjunction with the video trailer to of the area around the crossing under observation, while complete the necessary visual record. the second camera was zoomed in for a more detailed view of the crossing itself and the pedestrians using the crossing. The Observation Data Collection Approach entire outfit in the trailer was powered by a portable genera- tor or, if available, a nearby fixed electrical outlet. Despite the advantages of video data collection, the use of A drawback of the video trailer was that it required the only video data would have had some significant drawbacks. trailer to be driven to the study sites, and a place to park First, the amount of time necessary to pull all pedestrian and the trailer at each site had to be found. An issue at each study motorist characteristics from the video for each crossing site was whether there would need to be a trade-off between would be immense. Although rewinding and fast-forwarding the necessary viewing angle of the trailer and the need to be the video to review specific characteristics of crossing events relatively inconspicuous. At selected sites, it was not possible would be possible, this would have to be done multiple times to position the trailer in an inconspicuous location and still for each crossing. Second, the images obtained from the video

OCR for page 36
39 palmtop computer. A program was written for the PDA to collect information on various types of pedestrian crossing characteristics and save them to a database. Through a series of drop-down menus and radio buttons, the observation data could be collected quickly and accurately. Initial tests of the PDA revealed that the PDA was more efficient, so much so that more items were added to the PDA program. One of the screens of the PDA program is shown in Figure 18. This screen was used to collect specific information on the pedestrian crossing. At the top of the screen, the observer would note the type of pedestrian crossing using the radio buttons at the top. In the two columns below, the observer could then record 10 characteristics about the pedes- trian and the crossing maneuver: crossing direction, lighting conditions, gender, age, activation conditions, looking behav- Figure 16. Video record of pedestrians crossing in ior, start-of-crossing behavior, crosswalk compliance, the twilight. number of vehicles not stopping, and the distance between the pedestrian and the nearest vehicle that did stop or yield. Finally, there was a button for the observer to indicate did not always provide the detail and resolution necessary to whether the record was complete with all the items for the record certain characteristics. Gathering characteristics such crossing recorded. Occasionally, especially during periods of as pedestrian age and gender would not be possible if video high pedestrian traffic, the observer might be unable to was the only data available for each crossing. Figures 16 and record one or more items; noting "Incomplete" would be a 17 illustrate video records with insufficient resolution; the signal to look for the unrecorded items on the video during crossing pedestrians are circled for emphasis. the reduction process. Tapping the "Save" button would save Because of these limitations, it was decided that members the information for that crossing record into the database; of the research team should make personal visual observa- tapping the "Back" button would return the observer to the tions on site during the intervals of video data collection. The previous screen. first approach was to record these observations on a printed The primary benefit of using the PDA to collect this por- data sheet. However, initial tests revealed that, especially in tion of the data was that a large amount of data could be cases of high pedestrian volumes, it was extremely difficult to stored and easily downloaded later. The information gathered write down the necessary information in a timely manner and on each screen was saved to a database file for more detailed still ensure the accuracy of the data. calculations and analysis. The downloaded data was already The next attempted method of collecting observation formatted and ready for integration with the data collected data was a personal digital assistant (PDA), also known as a from the video, which further improved the efficiency of the reduction process. Both video data and observation data were post-processed manually to determine pedestrian volumes, pedestrian gap acceptance levels, pedestrian delay threshold levels, and behavior as pedestrians wait for an adequately sized gap. Site Characteristics Data Collection Approach In addition to motorist and pedestrian behavior, the research team also collected data on the characteristics of the study site that included roadway, overall location, and pedes- trian characteristics. These site characteristics data would be used for explaining the variation in treatment effectiveness at different locations (e.g., were posted speed limit and average Figure 17. Video record of pedestrian partially daily traffic volume strong predictors of treatment effective- obscured by background clutter. ness within a particular group of treatments?). Most of these