Principles and Guidance for Presenting Active Traffic Management Information to Drivers (2021) / Chapter Skim
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39 Figure 39. Static sign to explain dynamic shoulder lane symbols on I-495 in Northern Virginia (Google Maps)
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40 • ATM signs may be separate from or in conjunction with other static signage; • Australia presents a static sign to clarify a default speed limit when ATM signs are blank; • Some countries like Australia and New Zealand have flashing beacons adjacent to dynamic speed limit signs; • Some countries like the Netherlands use rotating drums with static images to convey information; • Some countries, including the Netherlands, Spain, and the United Kingdom use automated enforcement with dynamic speed limits to increase compliance, and may include static signs to convey the presence of speed cameras to drivers; • The United Kingdom has deployed pictogram displays on DMS to convey information about lane closures, instead of a sign over each lane.6 This practice is also seen in Figure 41 and is being considered as an alternative to signs over every lane in future Minnesota deployments. Figure 41.
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41 Table 9. Photos of international ATM strategy signage.
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42 Country, Strategy (Source) Photo of Deployment New Zealand Dynamic Speed Limit (New Zealand Transportation Agency)
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43 The Virginia DOT in conjunction with the Virginia Tech Transportation Institute (VTTI) has developed and is currently testing a smartphone app with 250 drivers that can replicate the I-66 ATM signs for in-vehicle messaging.
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44 Figure 42. In-vehicle display for INCZONE dynamic merge control and dynamic speed limit applications during closed field test demonstration in Maryland (Battelle)
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45 Chapter Summary The objective of the State of Practice review was to identify and document ATM deployments in the United States, as well as available guidance from the MUTCD. The review collected descriptions and photos of permanent and temporary ATM systems in 27 states, including deployments of multipurpose overhead lane use control signs, dynamic lane control and dynamic lane reversal, dynamic shoulder lanes, dynamic speed limits, dynamic junction control, dynamic merge control, and dynamic queue warning.
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46 Chapter 3: Literature Review The main objective of this activity was to search through ATM literature and to develop a literature synthesis based on those topics. Figure 45 illustrates an overview of our approach to the literature review.
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47 After the broad search process, two researchers assessed the total of 315 documents through a four-step process: (a) general relevance assessment with respect to ATM, (b)
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48 quality and quantity of applicable research findings vary greatly from topic to topic. A systematic approach is therefore needed for the literature review so that only the highest quality and most applicable data available will be used to inform content development of design principles and guidelines.
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49 From the literature, we have found general characteristics associated with effective traffic information. Previous studies have addressed specific information characteristics and their impact on driver performance and subjective ratings (e.g., Kantowitz et al., 1997)
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50 other topic areas, there were only a few studies that directly compared several ATM media. In this regard, the recently published Craig et al.
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51 The literature review identified a number of data sources that provide some very general design guidance for ATM messages. We had hoped to identify data sources/studies more focused on this study's objectives that could be used to provide answers to key research questions 1-4.
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52 Table 10: Research synthesis matrix. Kantowitz (1997)
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53 Chapter 4: Research Gaps Overview Based on the findings from the State of Practice and Literature reviews, we conducted an analysis to refine and prioritize research gaps. To complete the gap analysis, we used a structured approach utilized in previous gap analyses (e.g., Richard, Campbell, & Brown, 2012; Richard, Graving, Lichty, & Granda, 2013)
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54 4. Dynamic information can be disseminated to drivers using various media, whether agencies provide information for drivers via infrastructure, to vehicles for in-vehicle messaging, to third-party providers for smartphone applications, or a combination of these approaches.
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55 the various ATM strategies, drivers' preference regarding queue warning information will be asked (i.e., information type x ATM media x information receiving timing)
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56 Table 11: Definitions for rating within the three scales.
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57 Table 12. List of the key research questions and corresponding research gaps.
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58 Figure 47: Final scores of the 13 research gaps in three dimensions (color represents expected methods to conduct studies)
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59 (a) relevance, (b)
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60 Chapter 5: Empirical Studies This chapter describes the methods and findings from three research studies that were conducted to address the specific research gaps identified in earlier project activities. The studies consisted of two driving simulator experiments to examine some of the research gaps involving human factors issues regarding ATM message dissemination.
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61 General Approach to Experiments 1 and 2 The two experiments were conducted to examine human factors issues regarding ATM message dissemination and involved data collection in a driving simulator. In both simulator studies, participants drove for about 8 miles in a pre-designed straight four-lane highway.
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62 o average age = 45.33 (SD = 21.23) o n of male participants = 13 o n of female participants = 8 • Experiment 2 (eye-tracking data)
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63 speed was color-coded to indicate travel speed at or below the speed limit in blue, exceeding the speed limit by 10 mph or less in orange, and exceeding the speed limit by more than 10 mph in red. The application read a stream of data sent from the Battelle Driving Simulator.
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64 Figure 49. A screen capture from the smartphone application.
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65 Figure 50. Ergoneers head-mounted eye tracker.
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66 two baseline conditions for Experiment 118) before the main drive and had a short practice drive with the smartphone application across all experimental conditions.
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67 Experiment 1: Evaluating the Effects of Information Availability of Dynamic Lane Control on Driver Behavior and Distraction Overview The literature review found that there has been little to no research involving systematic comparisons of ATM media (including alternative media) in a situation where multiple types of ATM media are deployed and available at the same time.
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68 Driver distraction was measured by applying existing vehicle-industry guidelines for assessing the distraction impacts of in-vehicle devices. Two sets of guidelines were available for this objective.
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69 Methods While details of our general approach are described in the previous section, this section only includes methods specifically applied to Experiment 1. Independent Variable Experiment 1 included two baseline conditions.
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70 o Comparison of ATM applications o Comparison of presentation timing o Effectiveness of provisional signs Road layout The simulated road layout was designed to require drivers to change lanes according to the lane closure information. For each experimental condition (referred to as a block)
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71 Figure 53. Lane signal symbols.
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72 Results The results section consisted of three subsections: (a) driving measurements, (b)
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73 information from both the smartphone and the gantries significantly decreased percentage of time in merge/close lanes. • Post-hoc contrast testing showed that there was no significant difference between the always-on and just-in-time modes in lane compliance behavior (p = .83)
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74 Table 18. Glance measurement summary statistics for Experiment 1.
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75 Figure 57. Total glance time to the smartphone in seconds.
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76 Figure 58. Mean glance time to the smartphone in seconds.
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77 to understand. Only 42% of the participants thought they totally comprehended signs/symbols used in the junction control application.
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78 Figure 61. Ratings for how well each ATM application communicates.
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79 Figure 63. Usefulness ratings for overhead mounted sign and smartphone ATM applications.
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80 Survey responses (Comparison of Information Availability) This survey provided supplementary infomation about effectiveness and degree of distraction for the two different modes of information availability ("just-in-time" vs.
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81 Figure 67. Participants' timing assessment of the smartphone application in just-in-time mode.
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82 think that one of the presentation modes (always-on versus just-in-time) was more distracting than the other.
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83 Figure 72. Participants' self-reported likeliness to use the smartphone application to receive ATM information in the future.
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84 • Effectiveness Figure 77) • Ease of understanding (Figure 78)
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85 Figure 76. Importance ratings for provisional signs.
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86 participants (around 64%) indicated that the presentating timing of the "just-in-time" mode was fine, we interpreted this result as indicating that the "always-on" mode's information availability was preferred by drivers.
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87 Regarding research gap 1024, the survey asked participants' preferred way to receive ATM information for various applications and around 43-64% of the participants preferred to receive the ATM information through infrastructure. However, especially for "variable speed limit," "lane signaling," and "junction control," around 50% of the participants wanted to receive the information from either smartphone or in-vehicle displays along with the infrastructure display.
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88 Experiment 1 Summary Experiment 1 investigated the effects of the availability of the ATM information on driver behavior and distraction. The study focused on a dynamic lane signaling application and compared drivers' behavior under two levels of information availability ("always-on" mode, which displayed the lane closure information always vs.
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89 Experiment 2: Evaluating the Effects of Information Modality and Information Type of Dynamic Speed Limit Displays on Driver Behavior and Distraction. Overview Alternative ATM media can leverage unique information display characteristics compared to infrastructure-based ATM media.
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90 Table 19. Data sources for addressing gaps in Experiment 2.
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91 limits on the screen or gantry)
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