Principles and Guidance for Presenting Active Traffic Management Information to Drivers (2021)

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3 Chapter 2: State of the Practice A variety of ATM systems has been deployed in the United States and internationally. This section first presents guidance from the Manual of Uniform Traffic Control Devices (MUTCD). It is important to note that this effort excludes ATM deployments that use a standard traffic signal to present dynamic information to drivers (e.g., adaptive ramp metering, adaptive traffic signal control, and transit signal priority). Descriptions and photos of ATM systems in the United States are presented next, including: • Multi-Purpose Overhead Lane Use Control Sign Deployments; • Dynamic Lane Control and Dynamic Lane Reversal; • Dynamic Shoulder Lane Deployments; • Dynamic Speed Limit Deployments; • Dynamic Junction Control Deployments; • Dynamic Merge Control Deployments; and • Dynamic Queue Warning Deployments. Examples of Static Signage in Advance of ATM Deployments in the United States are also discussed, as well as descriptions of International ATM Deployments and existing In-Vehicle ATM Messaging. Documenting the state of practice by highlighting existing guidance for ATM deployments, and then presenting photos and descriptions of all identified ATM deployments in the United States and internationally, adds context to this effort by highlighting the variations in deployments and thus the needs for additional research and guidance for presenting dynamic ATM information to drivers. Use of Symbols in ATM Deployments and the Manual of Uniform Traffic Control Devices The MUTCD provides guidance in Chapter 4M on the use of lane control signals. Specifically, the following summarized guidance is provided for use of the following symbols in a steady mode, i.e., not flashing: • Downward Green Arrow: a road user is permitted to drive in the lane over which the arrow signal indication is located. • Yellow X: a road user is to prepare to vacate the lane over which the signal indication is located because a lane control change is being made to a red X signal indication. • Red X: a road user is not permitted to use the lane over which the signal indication is located and that this signal indication shall modify accordingly the meaning of other traffic controls present. • White Two-Way Left-Turn Arrow: a road user is permitted to use a lane over which the signal indication is located for a left turn, but not for through travel, with the understanding that common use of the lane by oncoming road users for left turns is also permitted. • White One-Way Left-Turn Arrow: a road user is permitted to use a lane over which the signal indication is located for a left turn (without opposing turns in the same lane), but not for through travel.

4 Use of these symbols are generally consistent on ATM lane use signage in the United States, although some locations use text instead of a yellow X to indicate a lane is closed ahead, as shown in Figure 2. To minimize driver confusion, some locations also display text to accompany symbols. Washington State DOT previously used a yellow X symbol with a distance text underneath, but found it to be less effective than the diagonal merge symbols and no longer uses it. Note that the Minnesota DOT sometimes uses a yellow X with text “1 mile” underneath instead of the text “lane closed ahead,” but only for a one-mile distance. Figure 2. ATM lane control displays used by different deployment sites to convey information to drivers (WSDOT, MnDOT, CDOT, Caltrans, and VDOT). Additionally, all known freeway applications of lane control signs in the United States have a blank sign for default conditions when there is no message to display, as permitted by the MUTCD. However, freeway applications of ATM lane control also display additional information like a caution message, merge, or a variable speed, as depicted in Figure 2. These additional uses are typically based on guidance provided in the MUTCD for other uses, such as the display of speed limits on a static sign or merging chevron arrows used for a work zone arrow board. Some symbols were implemented following the submission and approval of a request to experiment to FHWA, given the variation from the MUTCD guidance. Regulatory dynamic speed limit signs follow MUTCD guidance as black on white or white on black displays in a typical configuration, as seen on static signage. However, the way they are displayed can vary based on the coloration and extent of the dynamic element and the display technology, i.e., static sign with dynamic numbers versus a fully digital sign. Advisory dynamic speeds are less consistent in how they are displayed to drivers. Advisory dynamic speeds are generally based on MUTCD guidance in that they are yellow and black and often based on an / LOCATION WA: I-90, I-5, SR 520 2 + ONLY CAUTION MN: I-94, I-35W CO: I-25, US 36 CA: I-80 VA: I-66

5 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. Additional display examples will be exhibited below in Dynamic Speed Limit Deployments. The use of symbols (or not) for merging and caution also are inconsistent between sites. These symbols are mostly experimental due to the lack of guidance for these symbols in the MUTCD. One exception is that the Minnesota MUTCD, which provides additional guidance specific to the state of Minnesota, has long included guidance for use of the yellow arrow, as this symbol has been used on signage for a tunnel on I-94 for many years. Figure 3. Dynamic speed limit signs in Maine, left, and Oregon, right (MnDOT, Oregon DOT). Multipurpose Overhead Lane Use Control Sign Deployments Corridors in urban areas of several states currently have electronic signs over each lane on a series of gantries to support ATM strategies, and are under construction in three additional states (i.e., Illinois, Michigan, and Nevada), as presented in Table 1. Following the table are additional details and examples of multipurpose lane use control sign deployments. These deployments are generally similar in the information displayed to drivers: • Support display of regulatory or advisory dynamic speed limits, queue warning, and dynamic managed lane operations, including shoulder lane usage and restricted bus, high- occupancy vehicle (HOV), and high-occupancy toll (HOT) lanes for improved mobility by reducing crashes and managing recurring and non-recurring congestion. • Commonly a similar smaller-sized, full-color, dynamic sign, with capabilities to display various lane control symbols, as well as regulatory or advisory dynamic speed limits. • Green arrow and red X symbols are commonly used, consistent with MUTCD guidance. • Generally, default to blank for free-flow conditions. • Gantries are often spaced about a half-mile apart. These types of deployments are not always consistent in the types of information or how it is presented to drivers, including: • Different lane control symbols are used. A downward yellow arrow is sometimes used to denote “caution,” and diagonal arrows or a sequencing chevron are sometimes used for “merge” situations. Text is sometimes added above these symbols to facilitate driver understanding for “Merge,” “Closed,” or “Caution.” • ATM signs are sometimes presented on gantries with other static, regulatory signage.

6 • Larger dynamic message signs (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. A corridor may have supplemental DMS on every other gantry, for instance, or may have a mix of full-size DMS on some gantries and two medium-sized DMS on other gantries. • The display of regulatory or advisory dynamic speed limits can vary, as described in the dynamic speed limit deployments section. • The distance for providing advanced warning of a closed lane can vary by location. Deployments in Minnesota and Washington initially provided advanced warning a mile or more in advance, but have since shortened this distance. The following examples and photos of deployments highlight some of the different ways that overhead lane use signage presents information to drivers. Special attention is paid to the provision of supplemental DMS, including the number, size, and position, as well as particular features in the corridor, such as managed lanes. California. Features of the Caltrans lane use control system on I-80 in the San Francisco Bay Area include: • Gantries have two supplemental medium-sized DMS at the same level as the lane control signs mounted on the sides for the display of advisory dynamic speeds; it is more common at other sites to display speed information on the signage over the lanes. • In addition, a supplemental full-sized DMS is mounted on the right side of some gantries for the provision of messages. • Gantries do not include other static signage.

7 Table 1. Overhead dynamic lane control signage deployments and accompanying strategies in the United States. La ne C on tr ol Sp ee d Li m it Sh ou ld er L an e Q ue ue W ar ni ng O th er S tr at eg y State & Route System Details x x x x CA: I-80 The SMART corridor in the San Francisco Bay Area provides lane control symbols, DMS for queue warning, and advisory dynamic speeds, as well as dynamic alternate routing on arterials. x x x CO: US 36, I-25 South Systems support queue warning, dynamic lane control, and advisory dynamic speeds. A HOT lane is on each corridor. x x DE: I-295 Deployed on the Delaware Memorial Bridge as part of Advanced Traffic Management System. x MA: I-93 Lane control signage in Boston that can display only X and down arrow graphics. x x x x x MN: I-35W, I-94 Systems provide queue warnings and formerly displayed dynamic advisory speeds in Minneapolis. A short dynamic shoulder segment on I-35W extends a HOT lane to a major interchange, but will be retired following a highway reconstruction project. Dynamic junction control is used on a large dynamic message sign on I-94. x x x x x VA: I-66 Hard shoulder running for general purpose traffic during peak periods in peak directions began in 1992 on 7 miles of I-66 in Northern Virginia. Dynamic lane control, queue warning and dynamic speed limits installed in 2015 for all lanes on a longer segment allowed the dynamic shoulder lane segment to be based on real-time conditions. Entire system to be removed in 2017 due to a highway widening reconstruction project. x x x x WA: I-90, I-5 North, SR 520 Systems post dynamic speed limits and provide queue warning to drivers in Seattle. The signs can also quickly close entire lanes and caution drivers approaching an on-ramp with heavy merging traffic. Static signs with dynamic numbers provide travel times for alternate routes. x* x x* x OR: SR 217 Signs are used only for advisory speeds. Supplemental DMS provide travel time and incident information. *Software was pre-programmed with lane use control capabilities for future use, as necessary. x x x x IL: I-90 Under construction: will operate dynamic speed limits, dynamic lane control including a transit-only Flex Lane, and queue warning northwest of Chicago; managed by Illinois Tollway. x x x x MI: US 23 Under construction: includes a dynamic flex lane on the left shoulder, real-time queue warning, and possibly dynamic advisory speeds in Ann Arbor. x x x NV: I-15, I-515, US 95, US 93 Under construction: As part of Project NEON, a major construction project at the I-15 interchange with US 95, US 93, and I-515 in Las Vegas, a series of extra-large DMS are being installed to seamlessly span all lanes on those corridors to help manage traffic by displaying dynamic speed limits and lane control symbols. x TX: US 290 Discontinued: Signs in Austin are still in place, but have not been used for years.

8 Colorado. Features of the Colorado DOT lane use control systems on I-25 south and US 36 in the Denver area include: • Gantries on corridors in Denver have a mix of providing zero, one, or two medium-sized DMS on the side(s) of the gantry at differing levels relative to the signs over the lane, as shown in Figure 4 and Figure 5. • Some gantries include a large DMS above the lane control signs, and these gantries may also have medium-sized DMS, as shown in Figure 5. • Some of these gantries also include static guide signs and static signage with dynamic elements that support HOT lanes on US 36 and a part of I-25 as shown in Figure 4. Figure 4. Lane use control signage on US 36 in Denver (Google Maps). Figure 5. Lane use control signage on I-25 southbound in Denver (Google Maps). Delaware. Features of the Delaware Memorial Bridge lane use control systems on I-295 include: • Some gantries include static guide signs or full-size DMS. • Approximately every third gantry includes a two-part digital dynamic speed limit display in the middle, as seen in Figure 6. • Only a downward green arrow and X symbols can be displayed, as seen in Figure 6.

9 Figure 6. Lane use control signage on the I-295 Delaware Memorial Bridge (Google Maps). Illinois. The Illinois Tollway has erected gantries on the I-90 Jane Addams Tollway, as depicted in Figure 7 for lane use control operations that began in 2017. The slightly larger lane control sign on the left manages a dynamic shoulder “flex lane” for transit use only. Figure 7. Lane use control signage on I-90 Tollway northwest of Chicago (Google Maps). Massachusetts. Features of the Massachusetts DOT lane use control systems on I-93 in Boston include: • Some gantries include both static guide signs and full-sized supplemental DMS, as shown in Figure 8. • Lane control signs can only display a downward arrow and X. Figure 8. Lane use control signage on I-93 in Boston (Google Maps).

10 Minnesota. Features of the Minnesota DOT lane use control systems on I-35W and I-94 in the Minneapolis-St. Paul area include: • Gantries with lane control signage also contain static regulatory signage. • The deployment on I-35W also facilitates management of a HOT lane, which includes a dynamic shoulder lane segment, as seen in Figure 9. • The advisory dynamic speed shown in Figure 9 was not found to be effective and is no longer in use. • Gantries do not generally include supplemental DMS. Figure 9. Lane use control signage on I-35W in Minneapolis (Google Maps). Texas. Lane control signage on US 290 in Austin remains in place but is no longer used, as shown in Figure 10. Signs are capable of displaying only the downward arrow and X symbols. Figure 10. Lane use control signage on US 290 in Austin (Google Maps). Virginia. Features of the Virginia DOT (VDOT) lane use control system on I-66 in Northern Virginia include: • 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 11 and Figure 12. • One HOV lane operates in each direction of the entire ATM corridor. • Signage on a segment from US 50 to the I-495 Capital Beltway support dynamic shoulder lane operations, as seen in Figure 11.

11 • When the shoulder is closed, a red X is displayed over that lane, as seen in Figure 11, except at on-ramps where a diagonal yellow arrow is displayed under the text “merge.” • Gantries do not include other static signage, as seen in Figure 11 and Figure 12. • Additional gantries with a single lane control sign are provided at intermediate distances as necessary to help support dynamic shoulder operations. • Route symbols have been used as a dynamic junction control application in at least one location to help designate a lane exclusively for exiting traffic. Figure 11. Lane use control signage on I-66 in Northern Virginia (VDOT). Figure 12. Lane use control signage on I-66 in Northern Virginia (VDOT). 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 13. • Dynamic speed limits for the HOV lane may be up to 15 miles per hour higher or lower than general purpose lanes, depending on real-time traffic conditions, as shown in Figure 13. • A diagonal arrow (or arrows) is used with accompanying “merge” text, as shown in Figure 14. • A white diamond for the HOV lane is sometimes made smaller to include text, e.g., “2+ only” or “open to all,” as shown in Figure 14.

12 • Gantries on corridors in Seattle have a mix of providing one or two medium-sized DMS on the side(s) of the gantry at a slightly lower level than the signs over the lane, as shown in Figure 13, based on the number of lanes on the highway; one large DMS on the right side of the gantry, as shown in Figure 14; or no supplemental DMS in some locations. Figure 13. Lane use control signage on I-5 in Seattle (Google Maps). Figure 14. Lane use control signage on I-5 in Seattle (WSDOT).

13 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. Many of these deployments are found in bridges, tunnels, or managed lanes. Lane reversal on arterials is typically controlled with overhead lane control signs that use either a downward green arrow or red X to convey whether the lane is opened or closed. Additional dynamic signs may be used in advance of intersections to demark appropriate turning movements, as seen in Figure 15 and Figure 16. Static signs may support operations by presenting the hours that the reversible lane is open to traffic for the given direction. Figure 15. Arterial lane control signs on 5400 South in Taylorsville, Utah (Google Maps). Figure 16. Arterial lane control signs in Montgomery County, Maryland (Google Maps). Lane reversal on freeways often exists in barrier-separated managed lanes, either as a HOV lane or HOT lane. Given this context, signage for drivers is typically provided in advance of entry points to these lanes to convey whether the lane is opened or closed and, if applicable, the cost. Additionally, a moveable barrier or gates are generally present at the entry point to control access, as seen in Figure 17 and Figure 18.

14 Figure 17. Lane reversal deployment on I-595 HOT Lanes in Miami (Google Maps). Figure 18. Lane reversal deployment on I-5 HOV Lanes in Seattle (Google Maps). Alternatively, lane reversal on freeways may incorporate a moveable barrier system that can shift the barrier during peak traffic flows, which reduces or eliminates the need for signage. This approach has also been used in a work zone application in Minnesota. Dynamic Shoulder Lane Deployments As described above in the Multipurpose Overhead Lane Use Control Sign Deployments section, dynamic shoulder lanes are sometimes deployed in conjunction with other ATM strategies in urban areas. Currently, dynamic shoulder lane operations exist in five states, and will soon open in Michigan, as shown in Table 2. However, due to highway widening projects, dynamic shoulder lane operations in three locations will be ending within a year. Additional details on these deployments are provided below. Colorado. Dynamic shoulder lane use in Colorado is unique as it is a rural deployment. However, eastbound I-70 sometimes experiences high traffic volumes, particularly on Sundays in winter months due to travelers returning to Denver from skiing. The striping and full-size, overhead DMS displaying the red X and text indicating the lane can currently be used for emergency stopping only is visible in Figure 19. Figure 19. Dynamic shoulder lane on I-70 East in Colorado (Google Maps).

15 Table 2. Current and planned dynamic shoulder lane deployments in the United States. State & Route System Details CO: I-70 East The 13-mile dynamically-priced I-70 Mountain Express Peak Period Shoulder Lane near Idaho Springs opened in 2015, and operates only in peak periods. GA: I-85, SR 400 Dynamic Flex shoulder lanes include automatically controlled LED signs above the lane to indicate open/closed status in Atlanta. MN: I-35W North Ending soon: A 2-mile segment on I-35W in Minneapolis opened in 2009 to extend a managed lane to a major interchange, but will be retired in 2018 due to a highway widening reconstruction project. Dynamic lane control and dynamic queue warning is also present for all lanes, and advisory speeds were previously posted. NJ: I-78 Ending soon: Dynamic shoulder lanes on a segment of the I-78 New Jersey Turnpike in Newark is permitted at static times of day temporarily during a construction project on a parallel route. Dynamic speed limits are also present. VA: I-66 Ending soon: Hard shoulder running for general purpose traffic during peak periods in peak directions began in 1992 on a 7-mile segment of I-66 between US 50 and I-495 in Northern Virginia. ATM signs began operations in September 2015 to allow dynamic shoulder lane use on this segment based on real-time conditions, but will be retired in 2017 due to a highway widening reconstruction project. Dynamic lane control, queue warning and dynamic speed limits are also present for all lanes. VA: I-495 North This 1.5-mile segment opened in 2015 to allow traffic to travel on the left shoulder of northbound I-495 from where the 495 Express Lanes end to the George Washington Parkway in Northern Virginia. MI: US 23 Under construction: A dynamic flex lane on the left shoulder near Ann Arbor will be managed by a new system with signs over each lane that will provide real-time queue warning and possibly dynamic advisory speeds. Georgia. Near Atlanta, dynamic shoulder lane operations on SR 400 and a one-mile segment of I-85 north and are called Flex Lanes. The overhead dynamic lane control signage and explanatory roadside static signage that is used on I-85 north is visible in Figure 20. The middle section of the static sign covers a diagonal yellow arrow pointing up and to the right, which had initially been proposed to communicate to drivers to “merge” when the lane was closing. Figure 20. Dynamic shoulder lane on I-85 North near Atlanta (Google Maps). Minnesota. The dynamic shoulder lane on the two-mile segment of I-35W north is deployed in conjunction with the larger lane use control signage as presented above, using the same symbols, lane control signs, and managed lane signage. The dynamic shoulder lane deployment on I-35W

16 was initially installed with in-pavement lighting at the beginning of the segment, as seen in Figure 21; 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. Figure 21. Dynamic shoulder lane on I-35W North in Minneapolis (Minnesota DOT). New Jersey. During a construction project on a parallel route, the New Jersey Turnpike deployed lane control signs to temporarily allow a dynamic shoulder lane on I-78 in Newark, as seen in Figure 22. Figure 22. Dynamic shoulder lane on the I-78 New Jersey Turnpike in Newark (FHWA). Virginia. Dynamic shoulder lanes on the seven-mile segment of I-66 are currently deployed in conjunction with the larger lane use control signage as presented above, using the same symbols,

17 lane control signs, and managed lane signage. Additional gantries with a single lane control sign supplement the larger gantries to specifically support dynamic shoulder lane operations where needed, as shown in Figure 23. Figure 23 also shows how Virginia DOT is experimenting with 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, depicted in Figure 24. Installation of the overhead lane use control gantries for all lanes in 2015 also enabled dynamic shoulder lane operations on the segment, such that the lane is open to traffic almost twice as much as before, as warranted by real-time traffic conditions, including off-peak periods and weekends. Figure 23. Dynamic shoulder lane on I-66 in Northern Virginia (Google Maps). Figure 24. Previous static time-of-day shoulder lane on I-66 in Northern Virginia (FHWA). Additionally, in 2015 the Virginia DOT opened a 1.5-mile shoulder section for static time-of-day usage during peak periods downstream of the I-495 Express Lanes on the Capital Beltway in Northern Virginia, as shown in Figure 25.

18 Figure 25. Dynamic shoulder lane on I-495 North in Northern Virginia (Google Maps). Dynamic Speed Limit Deployments Deployments of dynamic speed limits, also known as variable speed limits (VSLs) are widespread across the United States, as presented in Table 3. Dynamic speed limit deployments are used in a variety of applications to improve safety, as well as mobility in both urban areas for recurring and non-recurring congestion, as presented in Table 4, and in rural areas for weather and work zone applications, as presented in Table 5 and Table 6, respectively. Table 3 presents a list of selected locations and routes of dynamic speed limit deployments in the United States, including those discussed above as a part of Multipurpose Overhead Lane Use Control Sign Deployments. Variations presented in this table include whether the deployment is: • A regulatory speed limit that can be enforced or an advisory speed. • Primarily deployed to help with urban congestion, weather issues, work zone management, or other purposes like downhill safe speeds for trucks. • Signage is placed on the roadside or overhead. • Signage is fully dynamic or is a static sign that has a cutout for the display of dynamic numeral digits. • Used on signage that is also used for other ATM strategies. Table 4, Table 5, and Table 6 present photos of the dynamic speed limit signs used in many of the current deployments in the United States, to help visualize the differences in how drivers receive the information. Specifically: • Advisory speeds are presented in a variety of ways, e.g., the provision of text to say, “reduce speed” or “advisory speed,” or not. • Regulatory dynamic speed limits generally conform to MUTCD specifications of black and white signage, however static signs with black text on a white background may have dynamic numerals that are either white on a black background or vice versa. • Some deployments include flashing beacons to attract driver attention when a reduced speed is displayed. • The dynamic displays fall on a spectrum, employing flip discs, older technology lights, or full-color LED displays.

19 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.

20 Table 3. Current, planned, and discontinued dynamic speed limit deployments in the United States. State and Route(s) Type Purpose Sign Location Sign Type W ith S ig ns F or O th er A TM S tr at eg ies System Location and Other Details R eg ul at or y A dv iso ry C on ge st io n W ea th er W or k Zo ne O th er R oa ds id e O ve rh ea d Fu lly D yn am ic D yn am ic D ig its AL: I-10 x x x x Low-visibility warning system with flashing beacons. Near Mobile. CA: I-80 x x x x x In San Francisco Bay Area. CO: US 36, I-25 x x x x x In Denver. CO: I-70 x x x x Downhill truck speed warning system. Displays safe speed for each truck >40,000 lbs. gross vehicle weight based on its axle configuration, gross vehicle weight, and the downgrade of the highway incline. In Eisenhower Tunnel. DE: I-295 x x x x x Older signage technology, not fully digital. On Delaware Memorial Bridge. DE: I-495 x x x x In Wilmington. FL: I-4, US 27 x x x x In Orlando and Fort Lauderdale. GA: I-285 x x x x In Atlanta. IA: I-35 x x x x Test project. For winter weather. Displayed on portable DMS. KS x x x x Eight portable dynamic speed limit trailers were retained. MD x x x x Eight portable dynamic speed limit trailers. ME: I-95, I-295 x x x x Sign says, “maximum speed,” but is black text on yellow. In Portland. MI: I-96 x x x x Test project. Portable orange trailer with flashing beacon. In Lansing. MN: I-35, I-494 x x x x Test project. Used on two work zone projects on I-35 and I-494. MO: US 54, US 63 x x x x Near Columbia. NH: I-93 x x x x Near Concord. NJ: I-95, I-78 x x x x Dynamic digits are flip segment/disks at this site. Near Newark. NV: I-80, US 395 Alt x x Near Reno.

21 State and Route(s) Type Purpose Sign Location Sign Type W ith S ig ns F or O th er A TM S tr at eg ies System Location and Other Details R eg ul at or y A dv iso ry C on ge st io n W ea th er W or k Zo ne O th er R oa ds id e O ve rh ea d Fu lly D yn am ic D yn am ic D ig its OH: US 33, I-270 x x x x Includes flashing beacon. Speeds reduce based only on workers being present, not congestion. Other routes have used dynamic speed zones in work zones. OR: US 26, I-84, SR 217 x x x x x x Near Portland. OR: I-84 x x x x Downhill truck speed advisory system. Near La Grande. OR: I-5, I-405 x x x x x In Portland. OR: US 26 x x x x At an intersection with SR 47. In Staley’s Junction. TN: I-75 x x x x x Near Calhoun. Began in 1973. TX: I-20 x x x x Test project: 6-months in 2014-2015. In Eastland County. TX: State Loop 1606 west x x x x Test project: 6-months in 2014. In San Antonio. TX: I-35 north x x x x Test project. In Temple. UT: I-80 x x x x Through Parley Canyon. UT: various x x x x 18 trailer-mounted signs in mostly rural work zones; an urban work zone application was unsuccessful. VA: I-66 x x x x x In Northern Virginia. VA: I-77 x x x x x Near Hillsville. VA: I-95/495 x x x x In Alexandria. WA: I-5 North, SR 520, I-90 x x x x x In Seattle. WA: I-90, US 2 x x x x x Dynamic digit signs are flip discs at this site. At Cascade Mountain passes. WY: I-80, I-25, SR 28 x x x x Four dynamic speed zones on over 100 miles of I-80, and over 25 miles on non-divided road SR 28. IL: I-90 x x x x x Under construction: On the Illinois Tollway northwest of Chicago. MI: US 23 x x x x x Under construction: In Ann Arbor.

22 State and Route(s) Type Purpose Sign Location Sign Type W ith S ig ns F or O th er A TM S tr at eg ies System Location and Other Details R eg ul at or y A dv iso ry C on ge st io n W ea th er W or k Zo ne O th er R oa ds id e O ve rh ea d Fu lly D yn am ic D yn am ic D ig its NV: I-15, I-515, US 95, US 93 x x x x x Under construction: In Las Vegas. MN: I-35W, I-94 x x x x x Discontinued: Other ATM strategies remain operational. In Minneapolis. MO: I-270 x x x x x Discontinued: Regulatory began in 2008, changed to advisory in 2011 until 2013. In St. Louis.

23 Table 4. Urban and congestion dynamic speed limit deployments in the United States. DE: I-295 (Google Maps) FL: I-4 – left (FHWA) CO: I-70 – right (Athey Creek Consultants) MN: I-35W (Google Maps) MO: I-270 – initial signs, left (Google Maps); later advisory signs, center (Google Maps) NH: I-93 – right (Google Maps)

24 NJ: I-78 New Jersey Turnpike (FHWA) OR: SR 217 –left (Oregon DOT) OR: I-405 – right (Google Maps) VA: I-66 (VDOT) WA: I-5 North (Google Maps)

25 Table 5. Weather dynamic speed limit deployments in the United States. AL: I-10 (Google Maps) DE: I-495 (Google Maps) IA: I-35 (Battelle) ME: I-295 (FHWA) OR: I-84 (Google Maps) TN: I-75 (FHWA) WA: I-90 UT: I-80 (Utah DOT) WY: I-80 (Wyoming DOT)

26 Table 6. Select dynamic speed limit deployments in work zones. MI: I-96 (FHWA1) MN (Minnesota DOT) MO (Iowa DOT) VA: I-495 (VDOT) UT (Utah DOT) 1 https://safety.fhwa.dot.gov/speedmgt/vslimits/docs/michiganvsl.pdf

27 Dynamic Junction Control Deployments In addition to the related practice presented above that is used in Seattle to caution drivers in the outside lane of heavy traffic at a downstream off-ramp and use of merge symbols on dynamic shoulder lane control signs at on-ramps when the shoulder is closed, there are two other examples of dynamic junction control that are presented here. California. On the SR 110 Arroyo Seco Parkway at I-5, dynamic junction control was deployed in 2010 to control access to allow a second exiting lane on the connector ramp shoulder during the afternoon peak period, 3-7pm Monday-Friday. In-pavement lighting was initially installed to show a solid white stripe across the lane when closed but was discontinued use after 2-3 years due to persistent maintenance issues and difficult access for maintenance staff. Overhead signs are fully dynamic, although not full color, and continue operations, as shown in Figure 26. A new project is underway to help manage lane movements with only digital overhead signage and improve compliance. Figure 26. Dynamic junction control on the SR 110 Arroyo Seco Parkway in Los Angeles (Caltrans2). Minnesota. The I-94 corridor in Minneapolis, where overhead lane use control signage is spaced every half-mile, includes one gantry an extra-large, full-color DMS instead of individual lane control signs. This DMS is capable of displaying lane control symbols when needed, but instead is often used for dynamic junction control, displaying a guide sign about a downstream exit that designates the outside lane as exit only based on real-time congestion conditions, as shown in Figure 27. Figure 27. Dynamic junction control on I-94 in Minneapolis displaying guide signs for an exit with and without an exit only lane designation (Google Maps). 2 https://ops.fhwa.dot.gov/publications/fhwahop14019/ch2.htm

28 Dynamic Merge Control Deployments A number of states have used dynamic merge control in work zone applications. In situations where one or more lanes is closed on a multi-lane roadway due to work zone activity, there are mobility and safety considerations for encouraging drivers to merge early or late, depending on the circumstances. A dynamic merge control system for a work zone application may consist of one or more portable DMS in series and placed on one or both sides of the roadway. As an example, the Florida DOT has used portable DMS for dynamic merge control in work zones and displayed “DO NOT PASS, MERGE HERE” when an early merge was desired, and “STAY IN LANE, MERGE AHEAD” when a late merge was desired. 3 A Minnesota DOT dynamic merge control deployment spaced several portable DMS at one-mile intervals to display “STOPPED TRAFFIC AHEAD, USE BOTH LANES” to encourage a late merge. Minnesota DOT also has used a static sign with flashing beacons to encourage a late merge based on real-time conditions, as seen in Figure 28. Figure 28. Dynamic merge control to encourage a late merge at a work zone in Minnesota (Minnesota DOT). Dynamic Queue Warning Deployments As described above in the Multipurpose Overhead Lane Use Control Sign Deployments section, dynamic queue warning is often deployed in conjunction with other ATM strategies in urban areas. However, many states also deploy temporary queue warning systems as a work zone mitigation strategy for improving safety. These systems often use fully dynamic, portable DMS to display messages to drivers depending on current speeds downstream, as depicted in Figure 29. These signs may be spaced at multiple locations upstream from the work zone, depending on expected queue length. Portable DMS may be placed on each side of the road on a multi-lane roadway so 3. http://www.fdot.gov/research/Completed_Proj/Summary_CN/FDOT_BD548-24_rpt.pdf

29 drivers will see the message even if there is a large truck obstructing the view; in this case, the Illinois DOT requires the sign displays to be synchronized, but since this is difficult to control the signs are staggered 500 feet apart so they are not directly side by side, which could confuse drivers trying to read both signs. As an example of messages displayed, Illinois DOT typically uses the system-provided recommendations, posting one of three messages on the signs based on real-time speeds downstream: • An advisory message if there is no congestion, e.g., left lane closed ahead, use caution; • A caution message when speeds drop below a certain threshold, e.g., slow traffic ahead; • A warning message when speeds are under 25 mph, e.g., slow traffic ahead, be prepared to stop. As an alternative, the Illinois DOT has also used static signs with flashing beacons as a queue warning system, e.g., “Slower traffic ahead when flashing.” Table 7 presents a list of dynamic queue warning systems that have been temporarily deployed in various states. It is likely that additional, similar temporary systems have been deployed in these and other states that are not documented. Table 7. Temporary dynamic queue warning system deployments in the United States. State Dynamic Queue Warning System Descriptions IA As part of the Traffic Critical Projects Program, Iowa DOT routinely uses portable DMS for queue warning systems and speed management in both urban and rural work zones around the state. IL Illinois DOT has deployed numerous queue warning systems on rural freeways for major construction projects, and several districts have on-call ITS contracts for the provision of queue warning systems on smaller, short-duration construction projects. MI Queue warning systems have been deployed for work zones in Jackson and Ann Arbor on I-94 and south of Detroit on I-275 and I-75 for a third project. MN Minnesota is testing a dynamic zipper merge including some queue warning using portable dynamic message sign in a work zone on US 52. Additionally, a couple recent projects on I-35 utilized a dynamic queue warning system with static signs and flashers. SD To manage high special event traffic volumes during the Sturgis Motorcycle Rally, an advanced queue detection system has been used to help warn motorists of stopped traffic on I-90. TX A queue warning system was deployed on I-35 to reduce the risk of crashes on a project in central Texas. The system included a portable work zone queue detection and warning system combined with portable rumble strips. WA Work zone projects at Snoqualmie Pass on I-90 sometimes use a shadow vehicle with a mounted dynamic message sign as a queue warning system to provide motorists with advanced warning of slowed or stopped traffic.

30 Figure 29. Typical, temporary dynamic queue warning system deployed for a work zone on I-35 in central Texas (Texas A&M Transportation Institute). Static Signage in Advance of ATM Deployments Because ATM deployments are relatively new to drivers in many parts of the United States, deploying agencies frequently take extra steps to facilitate driver understanding of the displays and symbols being used. In some cases, this may be a legal requirement that is mandated by the legislature, for example, as a condition for enforcement purposes or deploying a new strategy such as dynamic speed limits or a dynamic shoulder lane that is a change from current practices. Still, an often cited challenge and source of driver feedback to agencies is conveying the meaning of what the dynamic sign is displaying. For example, driver feedback in Seattle included confusion over whether the dynamic speed limit display was a feedback sign intended to convey an individual’s speed or the speed of traffic ahead, when it is intended as a regulatory speed limit; there was also driver confusion when the dynamic speed limit displayed was higher than congestion levels during stopped traffic. Agencies commonly conduct a public information campaign with local media before beginning a new type of ATM strategy in a region. Another approach is to add text, if possible, above or below the symbols displayed on lane control signage, such as “merge” or “closed” to convey the meaning of the symbols. Many ATM deployments post static signage in advance of the deployment to advise drivers. For a regulatory dynamic speed limit, some states may legally require a sign that alerts drivers that they are entering a dynamic speed zone for enforcement purposes. In other cases, a static sign may be placed in advance of a dynamic speed zone simply for informational purposes. A common example is a sign with text “variable speed zone ahead,” as used in Seattle, as seen in Figure 30, and one option for Utah DOT when using dynamic speed limits in work zones. An alternative example is shown in in Figure 31 for dynamic speed limits that have since been removed from I-270 in Missouri. These static signs may be accompanied by other features to grab driver attention, such as flags, as seen in Figure 30 for Seattle.

31 Figure 30. Static sign in advance of dynamic speed limits on SR 520 in Seattle (Google Maps). Figure 31. Static sign in advance of dynamic speed limits on I-270 in St. Louis (Courtesy of Missouri DOT) Dynamic shoulder lanes or lane control signage may also include static signage to advise drivers about the meaning of the symbols. The static signage used on the former dynamic shoulder lane deployment on I-66 in Northern Virginia was placed over the lane control sign on certain gantries to explain the symbols, and complemented by other roadside signs to present the hours of operation, as depicted in Figure 32. After lane control signs were placed over every lane on I- 66, the static roadside signs were updated, as seen in Figure 33. A similar overhead sign is used in advance of the dynamic shoulder on I-495 in Virginia, depicted in Figure 34, as well as a similar roadside sign used on I-85 in Georgia, shown in Figure 35. Figure 32. Static sign to explain former dynamic shoulder lane symbols and hours on I-66 in Northern Virginia (FHWA). Figure 33. Static sign to explain lane control symbols currently in use on I-66 in Northern Virginia (VDOT).

32 Figure 34. Static sign to explain dynamic shoulder lane symbols on I-495 in Northern Virginia (Google Maps). Figure 35. Static sign to explain dynamic shoulder lane symbols on I-85 near Atlanta (Google Maps). International ATM Deployments Many international deployments of ATM strategies in urban areas pre-date those found in the United States. Documentation of international ATM deployments has largely focused on those in Europe. For instance, an international scan conducted by Federal Highway Administration (FHWA), American Association of State Highway and Transportation Officials (AASHTO), and National Cooperative Highway Research Program (NCHRP) in 2006 examined ATM strategies in various European countries, as have subsequent FHWA and AASHTO reports.4,5,6 As a result of these efforts, most deployments described in the Multipurpose Overhead Lane Use Control Sign Deployments became operational within the last eight years and largely mirror the predecessor European deployments. For example, Minnesota DOT and Washington State DOT became the first agencies in 2009 and 2010 to deploy overhead lane signs for dynamic speed limits, dynamic queue warning, and dynamic lane control strategies in the United States, and these deployments have a similar design to those in Europe. Table 8 presents known examples of ATM strategies that are deployed internationally. 4. https://international.fhwa.dot.gov/pubs/pl07012/atm_eu07.pdf 5. https://international.fhwa.dot.gov/pubs/pl11004/pl11004.pdf 6. https://ops.fhwa.dot.gov/publications/fhwahop10031/fhwahop10031.pdf Table 8. International ATM strategy deployments. Country La ne C on tr ol Sp ee d Li m it Sh ou ld er L an e Q ue ue W ar ni ng Ju nc tio n C on tr ol Australia x Denmark x x Germany x x x x x Greece x x Netherlands x x x x x New Zealand x Spain x United Kingdom x x

33 As with deployments in the United States, many variations exist among international deployments in how information is presented to drivers. • ATM signs may be separate 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, as seen in Figure 36.7 This practice is being considered as an alternative to signs over every lane in future Minnesota deployments. Figure 36. Example of an ATM deployment in the United Kingdom (Capita Real Estate and Infrastructure) In-Vehicle ATM Messaging Connected vehicles and smartphone applications offer the potential to move messaging from infrastructure on the roadside into the vehicle. The current state of in-vehicle displays of ATM messages is mostly as research, test projects, or prototype applications, as described in this section. However, agencies are looking ahead to how technologies are evolving and how that may impact operations, but most continue to deploy traditional ITS and infrastructure-based ATM applications in locations it is warranted. Additional discussion on Agency Status and Considerations for the Provision of In-Vehicle Messages can be found in the following section. Several states have or are developing traveler information apps for smartphones that can provide real-time information to drivers as they travel down the roadway. While this information is not a 7. http://www.traffictechnologytoday.com/news.php?NewsID=83107

34 true example of in-vehicle ATM messaging, it is worth noting as a first step for states that are beginning to consider in-vehicle messaging that is possible with new technologies and a precursor to the connected vehicle environment. As research progresses and the reliability of these types of dynamic notifications is confirmed, enhancements may allow these types of notifications to become more advanced toward true in-vehicle ATM messaging. Currently, the 511 apps for Idaho, Iowa, Louisiana, and Minnesota all provide “hands-free, eyes-free audio notifications of traffic events while you drive,” that can alert drivers in advance similar to a dynamic queue warning.8,9,10,11 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. The app is not publicly available but is currently being tested to examine its utility in showing a virtual version of the gantry signs. VTTI is testing messages in this app that cannot be displayed on the ATM signs, e.g., issuing a truck entering warning as a work vehicle enters the travel lane. Similarly, Virginia DOT is also working with the University of Virginia to examine virtual DMS using geofence gateways to push information to the driver. Finally, the USDOT has supported the development and prototype testing of several Dynamic Mobility Applications that provide in-vehicle messaging of ATM information. The Response, Emergency Staging and Communications, Uniform Management, and Evacuation (R.E.S.C.U.M.E.) applications provide in-vehicle messaging, including an application called Incident Scene Work Zone Alerts for Drivers and Workers (INC-ZONE) that provides drivers both a visual and audio dynamic merge control and dynamic speed limit based on their current trajectory relative to a downstream temporary incident work zones, and is shown in Figure 37. This application was evaluated in a closed-track demonstration in Maryland.12 A second set of applications called Intelligent Network Flow Optimization (INFLO)13 includes two applications: • A dynamic queue warning application (Q-WARN) that provides real-time in-vehicle messages sufficiently far in advance for drivers to brake, change lanes, or change their route, as necessary, and • A dynamic speed limit application for Speed Harmonization (SPD-HARM) to dynamically adjust and coordinate maximum appropriate vehicle speeds based on real- time downstream conditions. The INFLO applications were evaluated as part of a small-scale demonstration test in Seattle that involved coordination of in-vehicle messages, seen in Figure 38 and Figure 39, with the messages displayed on the I-5 north overhead lane control signs.14 8 https://itunes.apple.com/us/app/idaho-511/id842945399?mt=8# 9 https://itunes.apple.com/us/app/louisiana-511/id1141141943?mt=8 10 https://itunes.apple.com/us/app/minnesota-511/id664709236?mt=8 11 https://itunes.apple.com/us/app/iowa-511/id528047799?mt=8 12 https://ntl.bts.gov/lib/57000/57000/57027/Rewrite_Final_1.13.16_FHWA-JPO-15-232.pdf 13 https://www.its.dot.gov/research_archives/dma/bundle/inflo_plan.htm 14 https://ntl.bts.gov/lib/56000/56200/56240/FHWA-JPO-15-223.pdf

35 Figure 37. In-vehicle display for INC- ZONE dynamic merge control and dynamic speed limit applications during closed field test demonstration in Maryland (Battelle). Figure 38. In-vehicle display for INFLO dynamic queue warning and dynamic speed limit applications during demonstration test in Seattle on I-5 north (Battelle). Figure 39. A smartphone was used as an in-vehicle display of information during the INC- ZONE and INFLO demonstrations (Battelle).