Principles and Guidance for Presenting Active Traffic Management Information to Drivers (2021) / Chapter Skim
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C O O P E R A T I V E R E S E A R C H P R O G R A M S CRP STAFF FOR NCHRP WEB-ONLY DOCUMENT 286 Christopher J Hedges, Director, Cooperative Research Programs Lori L
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i Table of Contents CHAPTER 1: INTRODUCTION ...............................................................................................................
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ii List of Tables TABLE 1.
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iii FIGURE 19.
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iv FIGURE 58.
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v List of Acronyms and Abbreviations AASHTO ................ American Association of State Highway and Transportation Officials ADT ...................................................................................................
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vi VPD............................................................................................................ Vehicles Per Day VSL .....................................................................................................
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1 Summary Active Traffic Management (ATM) strategies have become more common in the United States as State departments of transportation (DOTs)
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2 • Chapter 3 – Literature Review: This chapter synthesizes the available literature about displaying ATM information in key topic areas and identifies research gaps within those topics • Chapter 4 – Research Gaps: This chapter describes activities related to refining and prioritizing research gaps related displaying ATM information • Chapter 5 – Empirical Studies: This chapter describes the methodology and findings for three studies that were conducted during this project to address the key research gaps • Chapter 6 – Conclusions: This chapter integrates the available information about each research gap developed across all project activities To develop principles and guidance for presenting ATM information, different activities were conducted in both qualitative and quantitative ways. The key activities are described below.
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3 gaps, two driving simulator studies and a separate stakeholder engagement study were conducted. The first driving simulator study investigated the effects of the availability of the ATM information on driver behavior and distraction.
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4 the smartphone only presented navigation information)
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5 Guideline 1 stated that: Alternative ATM media must be coordinated with the primary information provided by infrastructure-based ATM media. The following attributes support good use of traditional and alternative ATM media.
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6 Chapter 1: Introduction ATM strategies have become more common in the United States, particularly in the last decade, as state DOTs grapple with increasing congestion and fewer dollars available to add capacity to keep pace. ATM strategies provide a more cost-effective solution to better manage traffic using the available capacity on the existing roadway network.
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7 Figure 1. Project sequence and tasks.
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8 Chapter 2: State of the Practice A variety of ATM systems have been deployed in the United States and internationally. This section first presents guidance from the MUTCD.
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9 Usage of these symbols is generally consistent on ATM lane use signage in the United States, although some locations use text instead of a yellow X to indicate that a lane is closed ahead, as shown in Figure 2. To minimize driver confusion, some locations also display text to accompany symbols.
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10 based on a static advisory speed sign that might be placed at a curve, for example. Figure 2 and Figure 3 show variations in how advisory speeds are displayed to drivers on dynamic signs.
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11 • Larger DMS are often on the gantries to display an additional text message, however, the size and position of DMS on the gantry vary, as well as the spacing. The supplemental DMS may be a full-size DMS in the center or right side of the gantry, or a medium-sized DMS on one or both sides of the roadway, for example.
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12 Table 1. Overhead dynamic lane control signage deployments and accompanying strategies in the United States.
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13 Figure 4. Lane use control signage on I-80 in the Bay Area (Caltrans)
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14 Figure 6. Lane use control signage on I-25 southbound in Denver (Google Maps)
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15 Illinois. The Illinois Tollway has erected gantries on the I-90 Jane Addams Tollway, as depicted in Figure 8 for lane use control operations that are expected to begin in 2017.
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16 • Gantries do not generally include supplemental DMS. Figure 10.
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17 • Gantries have a supplemental full-sized DMS at the same level as the lane control signs mounted on either the left or right side for the provision of messages, as shown in Figure 13 and Figure 14. • One HOV lane operates in each direction of the entire ATM corridor.
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18 Washington. Features of the Washington State DOT lane use control systems on I-5 northbound, I-90, and SR 520 in Seattle include: • A downward yellow arrow with "caution" text is used in the outside lane in advance of on-ramps with heavy traffic, as shown in Figure 15.
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19 Dynamic Lane Control and Dynamic Lane Reversal Lane control deployments exist in many locations to serve both arterial and freeway applications of lane reversal. However, most of these deployments operate on a static time-of-day basis, rather than dynamic, real-time congestion conditions.
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20 Figure 19. Lane reversal deployment on I-595 HOT Lanes in Miami (Sun Sentinel)
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21 Table 2. Current and planned dynamic shoulder lane deployments in the United States.
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22 was initially installed with in-pavement lighting at the beginning of the segment, as seen in Figure 23; however this was subsequently removed due to recurring maintenance issues. Dynamic shoulder lane usage will be suspended on this segment following a highway widening project that will begin in 2018.
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23 using the merge text and symbol at on-ramp locations when the dynamic shoulder is closed, instead of using the red X This segment had previously operated as a static time of day shoulder since 1992, using static and dynamic signage, as well as the colored pavement depicted in Figure 26.
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24 Figure 27. Dynamic shoulder lane on I-495 North in Northern Virginia (Google Maps)
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25 One additional item to note is the variations in how states provide information to drivers via supplemental DMS or dynamic elements on the dynamic speed limit signs to provide explanation for the reduced speed. For example, as depicted below in Table 5, an Oregon deployment on I-84 and a Washington deployment on I-90 at Snoqualmie Pass display a speed limit sign graphic on the left side of a full-size DMS and can provides text on the right side, e.g., "low visibility." Similarly, dynamic speed limit signs in Tennessee on I-75 includes a dynamic element that displays "fog." Supplemental medium- or full-sized DMS located in advance of or on the same gantry as dynamic speed limit signs can also provide explanation to drivers to justify and encourage travel at reduced speeds.
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26 Table 3. Current, planned, and discontinued dynamic speed limit deployments in the United States.
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