Traffic Control Devices and Measures for Deterring Wrong-Way Movements (2018)

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C-1 A P P E N D I X C Suggested Revisions to MUTCD In this appendix, researchers provide an overview of the suggested revisions to the language in the 2009 Manual on Uniform Traffic Control Devices with Revision Numbers 1 and 2, including their reasoning for the changes. This is followed by the detailed suggestions. Summary of and Reasons for Suggestions Revisions Regarding Traffic Control Devices for Wrong-Way Movements Section 1A.13—Definition for “#94, Intersection” • The research indicates that the 30-ft threshold criterion may not be appropriate for distinguishing between one or two intersections. However, the focus of this research effort was on wrong-way movements, and there are many other factors that impact the function of a divided highway crossing as one intersection or two. • Whether a divided highway functions as one or two intersections is determined by whether there is right-of-way control on the interior approaches. Interior right-of-way control is appropriate when two conditions are present: (1) the paths of opposing left turns from the divided roadway cross one another, and (2) there is adequate storage on the interior approach for a vehicle to stop at the stop/yield line. If the opposing left-turn paths from the divided highway do not cross or there is not adequate storage in the interior, then the divided highway crossing functions as a single intersection. Thus, the key to intersection right-of-way control is based on left-turn paths and interior storage. Researchers have revised the definition of intersection in element (c) to represent this. The revision eliminates the 30-ft criterion and allows the engineer to determine the intended function of a divided highway crossing. • Replacing the existing paragraph (c) in the definition for an intersection with a new paragraph (c) eliminates the need for paragraph (d) in the definition. The new paragraph (c) deletes the reference to the 30-ft separation distance. Section 1A.13—Definition for “#115, Median” • The definitions in early editions of the MUTCD duplicated those in the Uniform Vehicle Code (UVC). • No edition of the UVC (including the three most recent editions: 1987, 1992, and 2000) contain a definition for the term median. • The 1971 edition included a list of terms and definitions. • The 1978 and the 1988 editions of the MUTCD removed the terms and definitions since the terms had the definitions as presented in the UVC or the American Association of State Highway and Transportation Officials (AASHTO) highway definitions. • The written definition for median first appeared in the MUTCD in the 2000 edition. The chair of the National Committee on Uniform Traffic Control Devices (NCUTCD) Edit Committee during the time the 2000 MUTCD was being prepared verbally indicated that the definition for median was developed

C-2 by the committee based on judgment. As such, there is no documentation to support the creation of this definition. • The measurement of the median width was first illustrated in the MUTCD in the 2003 edition. • The current MUTCD definition for median width conflicts with the definition used in the AASHTO Green Book. The AASHTO Green Book definition preceded the MUTCD definition. The AASHTO definition was used as the basis in prior National Cooperative Highway Research Program research on median intersection design (Harwood et al. 1995). • Researchers suggested changing the definition and deleting how the median width is measured. Once the 30-ft criterion is removed (see above), the portion of the definition related to measuring width becomes unnecessary. Researchers reviewed the MUTCD for sections that reference median width and suggested changes where needed to accommodate the deletion of this definition. • Researchers considered including the sentence “The median width defines the available storage distance for the interior of a divided highway” but decided not to include this sentence because it is overly restrictive and the actual storage distance could be as wide as the AASHTO median width definition, although such storage would prevent left turns from the divided highway. Section 2A.23—Median Opening Treatments for Divided Highways with Wide Medians • The existing guidance language has been deleted due to the changes in the definition for intersection and median to eliminate the use of the 30-ft criterion for defining divided highway crossings as one or two intersections. • There are numerous factors that establish the divided highway crossing as one or two intersections. Khazraee and Hawkins (2015, 2016) developed figures for guiding the decision for a limited number of conditions. Due to the number of factors that can impact the function of a divided highway crossing, it is not appropriate to add these figures to the MUTCD. • This section has been revised to suggest treating the crossing as separate intersections when two conditions exist: left-turn paths cross, and there is adequate storage for the design vehicle. – Support language is also provided to indicate a general range for a median where it may be possible for the crossing to function as one or two intersections, depending upon the site-specific conditions. Section 2B.32—KEEP RIGHT and KEEP LEFT Signs • An option has been added as Paragraph 09a to allow the use of the sign in the median of a divided highway crossing that functions as a single intersection to make it consistent with the provisions of Section 2B.40—ONE WAY Signs. A support statement referencing Section 2B.40 has also been added (Paragraph 09b). Section 2B.37—DO NOT ENTER Sign • Paragraph 1 has been revised to incorporate changes approved by the NCUTCD in June 2013. Additional changes were made to this paragraph to make it consistent with the research suggestions for MUTCD changes. • Researchers have revised the language in Paragraphs 2 and 5 to clarify that the suggested sign is the one placed on the right-hand side of a driver traveling on the wrong direction. The sign on the left side of the wrong-way driver is optional. • Researchers have added asterisks to Figure 2B-12 to indicate the optional installation of the DO NOT ENTER sign, added the left-turn paths, added lane-use arrows (see Section 3B-20), and revised the figure title. • Researchers have added a new Figure 2B-12a to address DO NOT ENTER signs at a single- intersection divided highway crossing. Left-turn paths do not cross in this new figure.

C-3 • Paragraph 05a, approved by the NCUTCD in June 2014, has been added. This allows the use of red light-emitting diodes (LEDs) in the DO NOT ENTER sign. Section 2B.38—WRONG WAY Sign • Guidance has been added as Paragraph 02a to indicate that the sign should be on the same side of the road as the DO NOT ENTER sign. • Paragraph 03a, approved by the NCUTCD in June 2014, has been added. This allows the use of red LEDs in the WRONG WAY sign. • Asterisks have been added to Figure 2B-12 to indicate the optional installation of the WRONG WAY signs. • Researchers have added a new Figure 2B-12a to address WRONG WAY signs at a single-intersection divided highway crossing. Left-turn paths do not cross in this new figure. Section 2B.40—ONE WAY Signs • The language in Paragraphs 3, 4, and 5 has been revised to reflect the function of the crossing as one or two intersections rather than on the median width. The revised language in Paragraph 5 allows for the use of the optional far right ONE WAY sign at any divided highway intersection, regardless of median width/intersection function, to be consistent with how it is shown in Figure 2B-15. • Figure 2B-15 has been revised to make it applicable to two separate intersections. Optional lane-use arrows (see Section 3B.20) and a second divided highway sign have been added. A note regarding the centerline in the median opening has also been added. • Figure 2B-16 has been revised to make it applicable to a single intersection. The notes have been revised to indicate that the far right ONE WAY sign is optional even if only the other ONE WAY signs are used. The notes referencing other figures have also been revised. The reference to the median width distance has been removed. Optional lane-use arrows have been added (see Section 3B.20). • The researchers suggested deletion of Figure 2B-17. With the elimination of the method of showing how to measure median width, this figure is the same as Figure 2B-16 except for the geometrics of the divided highway left-turn lanes. The traffic control devices shown in the two figures are the same. • An option has been added as Paragraph 06a to allow the installation of ONE WAY signs at only one corner of the intersection of ramps and a crossroad. The language in Section 2B.41 where ONE WAY signs are required at only one corner conflicts with the language in 2B.40 where ONE WAY signs are required on the near right and far left corners. Section 2B.40a—Wrong-Way Traffic Control at Divided Highway Crossings • This is a new section that has been added to address the use of traffic control devices as a system to deter wrong-way movement at a divided highway intersection. Some of the language in this new section duplicates language in other sections (such as the rotation of the KEEP RIGHT sign). If this new section is added to the MUTCD, the researchers suggested deleting the duplicated language from the other sections. • One of the challenges of adding this section is that it addresses the use of both signs and markings, even though the section is in Part 2. However, since Section 2B.41 also addresses pavement markings, the researchers felt comfortable addressing markings in this section.

C-4 Section 2B.41—Wrong-Way Traffic Control at Interchange Ramps • Paragraph 1A requires ONE WAY signs at only one corner of the intersection, but Figure 2B-18 shows all ONE WAY signs as optional. The researchers have no research basis for indicating which ONE WAY signs are the optional signs. • An option has been added to Paragraph 3 (Item F) to allow use of movement prohibition signs as indicated in Figure 2B-18. • The reference in Paragraph 7 to Section 2B.41 has been changed to 2B.40a. When Section 2B.41 was in Chapter 2E in the 2003 MUTCD, this cross-reference was to the DO NOT ENTER sign section (2B.37). The cross-reference was lost in the publication of the 2009 MUTCD. With the addition of a new section on wrong-way traffic control at divided highway crossings (2B.40a), this reference has been changed from the DO NOT ENTER sign to the new section. Section 2B.42—Divided Highway Crossing Signs • The language in Paragraph 2 has been revised to reflect the function of the crossing as one or two intersections rather than on the median width. The language has also been revised to read better. Section 3B.20—Pavement Word, Symbol, and Arrow Markings • An option has been added as Paragraph 22a to specifically allow the use of lane-use arrows on the divided highway to deter wrong-way movement. • The researchers have deleted the reference to Figure 2B-17 in Paragraph 23 since they are suggesting this figure be deleted. The figure could be moved to Section 3B.20 as an example of the use of lane-use arrows in offset left-turn lanes if desired. • An option has been added as Paragraph 37a to allow the wrong-way arrow markings to be used in lieu of or in addition to lane-use arrows. Additional Revisions Section 2B.09—YIELD Sign Applications • The reference to 30 ft in Item B of Paragraph 1 has been deleted. The text has been revised to reflect function as one or two intersections. Section 4C.01—Studies and Factors for Justifying Traffic Control Signals • The language in Paragraph 12 has been revised to delete reference to the width of the median and to simply state that a divided highway crossing that functions as two separate intersections should be considered as one intersection for the purpose of a signal warrant analysis. The additional changes listed below were necessitated by the elimination of the 30-ft criterion for distinguishing function as one or two intersections. The research team did a search for the term “median” and identified 229 occurrences of the term. Each of these was evaluated to determine if the use was affected by the removal of the 30-ft criterion for distinguishing between function as one or two intersections. Language in the following two sections was all that was identified as needing revisions (in addition to those already discussed above).

C-5 Suggested Changes to MUTCD Proposed additions are shown in blue underline, and proposed deletions are shown in red strikethrough. Changes previously approved by NCUTCD, but not yet adopted by the Federal Highway Administration, are shown in green double underline for additions and green double strikethrough for deletions. PART 1: GENERAL CHAPTER 1A. GENERAL Section 1A.13 Definitions of Headings, Words, and Phrases in this Manual Standard: When used in this Manual, the text headings of Standard, Guidance, Option, and Support shall be defined as follows: 94. Intersection—intersection is defined as follows: (a) The area embraced within the prolongation or connection of the lateral curb lines, or if none, the lateral boundary lines of the roadways of two highways that join one another at, or approximately at, right angles, or the area within which vehicles traveling on different highways that join at any other angle might come into conflict. (b) The junction of an alley or driveway with a roadway or highway shall not constitute an intersection, unless the roadway or highway at said junction is controlled by a traffic control device. (c) If a highway includes two roadways that are 30 feet or more apart (see definition of Median), then every crossing of each roadway of such divided highway by an intersecting highway shall be a separate intersection. (c) If a highway includes two roadways separated by a median, then every crossing of each roadway of such divided highway by an intersecting highway shall be a separate intersection if the opposing left-turn paths cross and there is sufficient interior storage for the design vehicle. (d) If both intersecting highways include two roadways that are 30 feet or more apart, then every crossing of any two roadways of such highways shall be a separate intersection. (de) At a location controlled by a traffic control signal, regardless of the distance between the separate intersections as defined in (c) and (d) above: (1) If a stop line, yield line, or crosswalk has not been designated on the roadway (within the median) between the separate intersections, the two intersections and the roadway (median) between them shall be considered as one intersection; (2) Where a stop line, yield line, or crosswalk is designated on the roadway on the intersection approach, the area within the crosswalk and/or beyond the designated stop line or yield line shall be part of the intersection; and (3) Where a crosswalk is designated on a roadway on the departure from the intersection, the intersection shall include the area extending to the far side of such crosswalk.

C-6 115. Median—the portion of a highway separating opposing directions of the traveled way area between two roadways of a divided highway measured from edge of traveled way to edge of traveled way. The median excludes turn lanes. The median width might be different between intersections, interchanges, and at opposite approaches of the same intersection. PART 2 SIGNS CHAPTER 2A. GENERAL Section 2A.23 Median Opening Treatments for Divided Highways with Wide Medians Guidance: 01 Where divided highways are separated by median widths at the median opening itself of 30 feet or more, median openings should be signed as two separate intersections. 01 A divided highway crossing should be signed and marked as separate intersections when both of the following conditions are present: A. The paths of opposing left turns from the divided highway cross each other (see Figure A). B. There is adequate storage in the interior approaches for the types of vehicles expected to cross the divided highway. 02 If both of the conditions in paragraph 2 do not exist, the divided highway crossing should be signed and marked as a single intersection. 03 At the crossing of two divided highways, engineering judgement should be used to determine the number of separate intersections. Support: 04 Research has indicated that median widths (including left-turn lanes) less than 30 ft typically function as a single intersection and that median widths greater than 85 ft typically function as two intersections. Divided highway crossings with median widths between 30 and 85 ft can function as one or two intersections depending upon the geometric design of the divided highway crossing. Factors that impact the function of a crossing as a single intersection or multiple intersections include the left-turn paths, the interior storage, the offset of the opposing left-turn lanes, the length of the median opening (measured parallel to the centerline of the divided highway), and the geometric design of the median noses. [Add Figure A to define left-turn paths.]

C-7 a. Opposing Paths Cross. b. Opposing Paths Do Not Cross. Figure A. Types of Left-Turn Paths at a Divided Highway Crossing. PART 2 SIGNS CHAPTER 2B. REGULATORY SIGNS, BARRICADES, AND GATES Section 2B.32 Keep Right and Keep Left Signs (R4-7, R4-8) Option: 01 The Keep Right (R4-7) sign (see Figure 2B-10) may be used at locations where it is necessary for traffic to pass only to the right-hand side of a roadway feature or obstruction. The Keep Left (R4-8) sign (see Figure 2B-10) may be used at locations where it is necessary for traffic to pass only to the left-hand side of a roadway feature or obstruction. Guidance: 02 At locations where it is not readily apparent that traffic is required to keep to the right, a Keep Right sign should be used. 03 If used, the Keep Right sign should be installed as close as practical to approach ends of raised medians, parkways, islands, and underpass piers. The sign should be mounted on the face of or just in front of a pier or other obstruction separating opposite directions of traffic in the center of the highway such that traffic will have to pass to the right-hand side of the sign. Standard: 04 The Keep Right sign shall not be installed on the right-hand side of the roadway in a position where traffic must pass to the left-hand side of the sign. Option: 05 The Keep Right sign may be omitted at intermediate ends of divisional islands and medians. 06 Word message KEEP RIGHT (LEFT) with an arrow (R4-7a or R4-7b) signs (see Figure 2B- 10) may be used instead of the R4-7 or R4-8 symbol signs. 07 Where the obstruction obscures the Keep Right sign, the minimum placement height may be increased for better sign visibility. 08 A narrow Keep Right (R4-7c) sign (see Figure 2B-10) may be installed on the approach end of a median island that is less than 4 feet wide at the point where the sign is to be located.

C-8 Standard: 09 A narrow Keep Right (R4-7c) sign shall not be installed on a median island that has a width of 4 feet or more at the point where the sign is to be located. Option: 09a The Keep Right sign may be installed in the median of a divided highway crossing that functions as a single intersection such that it is visible to traffic on the divided highway and the crossroad approach. Support 09b Section 2B.40 provides more information about the use of the Keep Right sign in combination with or in lieu of One Way signs at divided highway crossings. Section 2B.37 DO NOT ENTER Sign (R5-1) Standard: 01 The DO NOT ENTER (R5-1) sign (see Figure 2B-11) shall be used where traffic is prohibited a two-way roadway becomes a one-way roadway as shown in Figure 2B-14, at divided highway crossings as shown in Figures 2B-12 and 2B-12a (see Section 2B.40a), and near the downstream end of an Interchange exit ramp as shown in Figure 2B-18 (see Section 2B.41).from entering a restricted roadway. [Note: Approved by NCUTCD on 6-28- 13.] Guidance: 02 The DO NOT ENTER sign, if used, should be placed directly in view of a road user at the point where a road user could wrongly enter a divided highway, one-way roadway, or ramp (see Figure 2B-12). The sign should be mounted on the right-hand side of a road user traveling in the wrong direction on the roadway, facing traffic that might enter the roadway or ramp in the wrong direction. 03 If the DO NOT ENTER sign would be visible to traffic to which it does not apply, the sign should be turned away from, or shielded from, the view of that traffic. Option: 04 The DO NOT ENTER sign may be installed where it is necessary to emphasize the one-way traffic movement on a ramp or turning lane. 05 A second DO NOT ENTER sign may be used on the left-hand side of a road user traveling in the wrong direction on the roadway may be used, particularly where traffic approaches from an intersecting roadway (see Figure 2B-12). 05a Red LEDs may be installed within the border of the DO NOT ENTER sign to enhance the conspicuity of the sign. The LEDs may be vehicle actuated to flash at the rates as shown in Section 2A.07 (paragraph 09). [Note: Approved by NCUTCD on 6/28/2014.] Support: 06 Section 2B.41 contains information regarding an optional lower mounting height for DO NOT ENTER signs that are located along an exit ramp facing a road user who is traveling in the wrong direction. [Revise Figure 2B-12 as shown.]

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C-10 [Add Figure 2B-12a to address DO NOT ENTER signs for single intersection.] Section 2B.38 WRONG WAY Sign (R5-1a) Option: 01 The WRONG WAY (R5-1a) sign (see Figure 2B-11) may be used as a supplement to the DO NOT ENTER sign where an exit ramp intersects a crossroad or a crossroad intersects a one-way roadway in a manner that does not physically discourage or prevent wrong-way entry (see Figure 2B-12). Guidance: 02 If used, the WRONG WAY sign should be placed at a location along the exit ramp or the one- way roadway farther from the crossroad than the DO NOT ENTER sign (see Sections 2B.40a and Section 2B.41). 02a The WRONG WAY sign should be placed on the same side of the road as the DO NOT ENTER sign. Support: 03 Section 2B.41 contains information regarding an optional lower mounting height for WRONG WAY signs that are located along an exit ramp facing a road user who is traveling in the wrong direction.

C-11 03a Red LEDs may be installed within the border of the WRONG WAY sign to enhance the conspicuity of the sign. The LEDs may be vehicle actuated to flash at the rates as shown in Section 2A.07(09). [Note: Approved by NCUTCD on 6/28/2014.] Section 2B.40 ONE WAY Signs (R6-1, R6-2) Standard: 01 Except as provided in Paragraph 6, the ONE WAY (R6-1 or R6-2) sign (see Figure 2B- 13) shall be used to indicate streets or roadways upon which vehicular traffic is allowed to travel in one direction only. 02 ONE WAY signs shall be placed parallel to the one-way street at all alleys and roadways that intersect one-way roadways as shown in Figure 2B-14. 03 At the crossing of a roadway with a divided highway that functions as separate intersections, At an intersection with a divided highway that has a median width at the intersection itself of 30 feet or more, ONE WAY signs shall be placed, visible to each crossroad approach, on the near right and far left corners of each intersection with the directional roadways (see Figure 2B-15). 04 At the crossing of a roadway with a divided highway that functions as a single intersection, At an intersection with a divided highway that has a median width at the intersection itself of less than 30 feet, Keep Right (R4-7) signs and/or ONE WAY signs shall be installed (see Figures 2B-16 and 2B-17). If Keep Right signs are installed, they shall be placed as close as practical to the approach ends of the medians and shall be visible to traffic on the divided highway and the applicable each crossroad approach. If ONE WAY signs are installed, they shall be placed on the near right and far left corners of the intersection and shall be visible to each crossroad approach. Option: 05 At the crossing of a roadway with a divided highway, regardless of function as a single or separate intersections, At an intersection with a divided highway that has a median width at the intersection itself of less than 30 feet, ONE WAY signs may also be placed on the far right corner of the intersection as shown in Figures 2B-15 and 2B-16 and 2B-17. 06 ONE WAY signs may be omitted on the one-way roadways of divided highways, where the design of interchanges indicates the direction of traffic on the separate roadways. 06a ONE WAY signs may be omitted from one corner of the intersection of a crossroad with an interchange ramp (see Section 2B.41). Standard: 07 If used at unsignalized intersections with one-way streets, ONE WAY signs shall be placed on the near right and the far left corners of the intersection facing traffic entering or crossing the one-way street (see Figure 2B-14). 08 If used at signalized intersections with one-way streets, ONE WAY signs shall be placed near the appropriate signal faces, on the poles holding the traffic signals, on the mast arm or span wire holding the signals, or at the locations specified for unsignalized intersections. 09 At unsignalized T-intersections where the roadway at the top of the T-intersection is a one-way roadway, ONE WAY signs shall be placed on the near right and the far side of the intersection facing traffic on the stem approach (see Figure 2B-14).

C-12 10 At signalized T-intersections where the roadway at the top of the T-intersection is a one-way roadway, ONE WAY signs shall be placed near the appropriate signal faces, on the poles holding the traffic signals, on the mast arm or span wire holding the signals, or at the locations specified for unsignalized intersections. Option: 11 Where the central island of a roundabout allows for the installation of signs, ONE WAY signs may be used instead of or in addition to Roundabout Directional Arrow (R6-4 series) signs (see Section 2B.43) to direct traffic counter-clockwise around the central island. Guidance: 12 Where used on the central island of a roundabout, the mounting height of a ONE WAY sign should be at least 4 feet, measured vertically from the bottom of the sign to the elevation of the near edge of the traveled way. Support: 13 Using ONE WAY signs on the central island of a roundabout might result in some drivers incorrectly concluding that the cross street is a one-way street. Using Roundabout Directional Arrow signs might reduce this confusion. However, using ONE WAY signs might be necessary in States that have defined a roundabout as a series of T-intersections. Option: 14 The BEGIN ONE WAY (R6-6) sign (see Figure 2B-13) may be used notify road users of the beginning point of a one direction of travel restriction on the street or roadway. The END ONE WAY (R6-7) sign (see Figure 2B-13) may be used notify road users of the ending point of a one direction of travel restriction on the street or roadway. [Revise Figures 2B-15 and 16 as shown.]

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C-14 Section 2B.40a Wrong-Way Traffic Control at Divided Highway Crossings Support: 01 At the crossing of a divided highway with a roadway, the type and location of traffic control devices used to deter wrong-way movements depend upon the classification of the crossing as a single intersection or two intersections (see Section 2A.23). Standard: 02 When a divided highway crossing functions as a single intersection, the following traffic control devices shall be used to deter wrong-way movements: A. ONE WAY signs shall be installed on the near right and far left corners of the intersection (see Figure 2B-16). B. A DO NOT ENTER sign shall be installed on the median side of the roadway (the right-hand side of a road user traveling in the wrong direction) (See Figure 2B-12a). C. A centerline marking shall not be installed in the median portion of the crossroad when the divided highway crossing functions as a single intersection. Option: 03 When a divided highway crossing functions as a single intersection, the following traffic control devices may be used to deter wrong-way movements: A. A DO NOT ENTER sign may be installed on the left-hand side of a road user traveling in the wrong direction.

C-15 B. A WRONG WAY sign may be used to supplement any DO NOT ENTER signs (see Section 2B.38) (see Section 2B.37). C. A KEEP RIGHT sign may be installed in the median in lieu of, or as a supplement to, the required ONE WAY signs. D. Lane-use arrows may be used on the through lanes of the divided highway near the crossroad (see Section 3B.20). Wrong-way arrow markings may be used in a through or shared-use lane upstream of the intersection (see Section 3B.20). Guidance: 04 If used in the median of a divided highway crossing, the KEEP RIGHT sign shall be oriented so that it is visible to traffic on the divided highway and the applicable crossroad approach. Standard: 05 When a divided highway crossing functions as two separate intersections, the following traffic control devices shall be used to deter wrong-way movements: A. ONE WAY signs shall be installed on the near right and far left corners of each intersection (see Figure 2B-15). B. A DO NOT ENTER sign shall be installed on the median side of the roadway (the right-hand side of a road user traveling in the wrong direction) (see Figure 2B-12). C. A STOP or YIELD sign shall be installed on the interior approaches (median portion of the crossroad). Guidance: 06 When a divided highway crossing functions as two separate intersections, the following traffic control devices should be used to deter wrong-way movements: A. Where Stop or Yield lines are provided on the interior approaches, a centerline marking should be installed between the Stop or Yield lines on each interior approach. Option: 07 When a divided highway crossing functions as two separate intersections, the following traffic control devices may be used to deter wrong-way movements: A. A DO NOT ENTER sign may be installed on the left-hand side of a road user traveling in the wrong direction (see Section 2B.37). B. A WRONG WAY sign may be used to supplement any DO NOT ENTER sign (see Section 2B.38). C. Lane-use arrows may be used on the through lanes of the divided highway near the crossroad (see Section 3B.20). Wrong-way arrow markings may be used in a through or shared-use lane upstream of the intersection (see Section 3B.20). D. Stop or Yield lines may be used on the interior approaches (see Section 3B.16). Section 2B.41 Wrong-Way Traffic Control at Interchange Ramps Standard: 01 At interchange exit ramp terminals where the ramp intersects a crossroad in such a manner that wrong-way entry could inadvertently be made, the following signs shall be used (see Figure 2B-18): A. At least one ONE WAY sign for each direction of travel on the crossroad shall be placed where the exit ramp intersects the crossroad.

C-16 B. At least one DO NOT ENTER sign shall be conspicuously placed near the downstream end of the exit ramp in positions appropriate for full view of a road user starting to enter wrongly from the crossroad. C. At least one WRONG WAY sign shall be placed on the exit ramp facing a road user traveling in the wrong direction. Guidance: 02 In addition, the following pavement markings should be used (see Figure 2B-18): A. On two-lane paved crossroads at interchanges, double solid yellow lines should be used as a center line for an adequate distance on both sides approaching the ramp intersections. B. Where crossroad channelization or ramp geometrics do not make wrong-way movements difficult, a lane-use arrow should be placed in each lane of an exit ramp near the crossroad terminal where it will be clearly visible to a potential wrong-way road user. Option: 03 The following traffic control devices may be used to supplement the signs and pavement markings described in Paragraphs 1 and 2: A. Additional ONE WAY signs may be placed, especially on two-lane rural crossroads, appropriately in advance of the ramp intersection to supplement the required ONE WAY sign(s). B. Additional WRONG WAY signs may be used. C. Slender, elongated wrong-way arrow pavement markings (see Figure 3B-24) intended primarily to warn wrong-way road users that they are traveling in the wrong direction may be placed upstream from the ramp terminus (see Figure 2B-18) to indicate the correct direction of traffic flow. Wrong-way arrow pavement markings may also be placed on the exit ramp at appropriate locations near the crossroad junction to indicate wrong-way movement. The wrong-way arrow markings may consist of pavement markings or bidirectional red-and-white raised pavement markers or other units that show red to wrong-way road users and white to other road users (see Figure 3B-24). D. Lane-use arrow pavement markings may be placed on the exit ramp and crossroad near their intersection to indicate the permissive direction of flow. E. Freeway entrance signs (see Section 2D.46) may be used. F. Movement prohibition signs may be used on the approaches to the exit ramp. Guidance: 04 On interchange entrance ramps where the ramp merges with the through roadway and the design of the interchange does not clearly make evident the direction of traffic on the separate roadways or ramps, a ONE WAY sign visible to traffic on the entrance ramp and through roadway should be placed on each side of the through roadway near the entrance ramp merging point as illustrated in Figure 2B-19. Option: 05 At locations where engineering judgment determines that a special need exists, other standard warning or prohibitive methods and devices may be used as a deterrent to the wrong- way movement. 06 Where there are no parked cars, pedestrian activity or other obstructions such as snow or vegetation, and if an engineering study indicates that a lower mounting height would address

C-17 wrong-way movements on freeway or expressway exit ramps, a DO NOT ENTER sign(s) and/or a WRONG WAY sign(s) that is located along the exit ramp facing a road user who is traveling in the wrong direction may be installed at a minimum mounting height of 3 feet, measured vertically from the bottom of the sign to the elevation of the near edge of the pavement. Support: 07 Section 2B.40a 2B.41 contains further information on signing to avoid wrong-way movements at at-grade intersections on expressways. Section 2B.42 Divided Highway Crossing Signs (R6-3, R6-3a) Standard: 01 On unsignalized minor-street approaches from which both left turns and right turns are permitted onto a divided highway that has a median width at the intersection itself of 30 feet or more, except as provided in Paragraph 2, a Divided Highway Crossing (R6-3 or R6-3a) sign (see Figure 2B-13) shall be used to advise road users that they are approaching an intersection with a divided highway (see Figure 2B-15). Option: 02 If a divided highway that has a median width at the intersection itself of 30 feet or more crossing functions as separate intersections (see Section 2A.23) and meets both of the following criteria, the Divided Highway Crossing signs facing the unsignalized minor-street approaches may be omitted. A. Traffic volume on the cross road of less than 400 AADT. B. Speed limit on the cross road of 25 mph or less. 03 A Divided Highway Crossing sign may be used on signalized minor-street approaches from which both left turns and right turns are permitted onto a divided highway to advise road users that they are approaching an intersection with a divided highway. Standard: 04 If a Divided Highway Crossing sign is used at a four-legged intersection, the R6-3 sign shall be used. If used at a T-intersection, the R6-3a sign shall be used. 05 The Divided Highway Crossing sign shall be located on the near right corner of the intersection, mounted beneath a STOP or YIELD sign or on a separate support. Option: 06 An additional Divided Highway Crossing sign may be installed on the left-hand side of the approach to supplement the Divided Highway Crossing sign on the near right corner of the intersection.

C-18 PART 3 MARKINGS CHAPTER 3B. PAVEMENT AND CURB MARKINGS Section 3B.20 Pavement Word, Symbol, and Arrow Markings Support: 01 Word, symbol, and arrow markings on the pavement are used for the purpose of guiding, warning, or regulating traffic. These pavement markings can be helpful to road users in some locations by supplementing signs and providing additional emphasis for important regulatory, warning, or guidance messages, because the markings do not require diversion of the road user’s attention from the roadway surface. Symbol messages are preferable to word messages. Examples of standard word and arrow pavement markings are shown in Figures 3B-23 and 3B- 24. Option: 02 Word, symbol, and arrow markings, including those contained in the “Standard Highway Signs and Markings” book (see Section 1A.11), may be used as determined by engineering judgment to supplement signs and/or to provide additional emphasis for regulatory, warning, or guidance messages. Among the word, symbol, and arrow markings that may be used are the following: A. Regulatory: 1. STOP 2. YIELD 3. RIGHT (LEFT) TURN ONLY 4. 25 MPH 5. Lane-use and wrong-way arrows 6. Diamond symbol for HOV lanes 7. Other preferential lane word markings B. Warning: 1. STOP AHEAD 2. YIELD AHEAD 3. YIELD AHEAD triangle symbol 4. SCHOOL XING 5. SIGNAL AHEAD 6. PED XING 7. SCHOOL 8. R X R 9. BUMP 10. HUMP 11. Lane-reduction arrows C. Guide: 1. Route numbers (route shield pavement marking symbols and/or words such as I-81, US 40, STATE 135, or ROUTE 10) 2. Cardinal directions (NORTH, SOUTH, EAST, or WEST) 3. TO 4. Destination names or abbreviations thereof

C-19 Standard: 03 Word, symbol, and arrow markings shall be white, except as otherwise provided in this Section. 04 Pavement marking letters, numerals, symbols, and arrows shall be installed in accordance with the design details in the Pavement Markings chapter of the “Standard Highway Signs and Markings” book (see Section 1A.11). Guidance: 05 Letters and numerals should be 6 feet or more in height. 06 Word and symbol markings should not exceed three lines of information. 07 If a pavement marking word message consists of more than one line of information, it should read in the direction of travel. The first word of the message should be nearest to the road user. 08 Except for the two opposing arrows of a two-way left-turn lane marking (see Figure 3B-7), the longitudinal space between word or symbol message markings, including arrow markings, should be at least four times the height of the characters for low-speed roads, but not more than ten times the height of the characters under any conditions. 09 The number of different word and symbol markings used should be minimized to provide effective guidance and avoid misunderstanding. 10 Except for the SCHOOL word marking (see Section 7C.03), pavement word, symbol, and arrow markings should be no more than one lane in width. 11 Pavement word, symbol, and arrow markings should be proportionally scaled to fit within the width of the facility upon which they are applied. Option: 12 On narrow, low-speed shared-use paths, the pavement words, symbols, and arrows may be smaller than suggested, but to the relative scale. 13 Pavement markings simulating Interstate, U.S., State, and other official highway route shield signs (see Figure 2D-3) with appropriate route numbers, but elongated for proper proportioning when viewed as a marking, may be used to guide road users to their destinations (see Figure 3B- 25). Standard: 14 Except at the ends of aisles in parking lots, the word STOP shall not be used on the pavement unless accompanied by a stop line (see Section 3B.16) and STOP sign (see Section 2B.05). At the ends of aisles in parking lots, the word STOP shall not be used on the pavement unless accompanied by a stop line. 15 The word STOP shall not be placed on the pavement in advance of a stop line, unless every vehicle is required to stop at all times. Option: 16 A yield-ahead triangle symbol (see Figure 3B-26) or YIELD AHEAD word pavement marking may be used on approaches to intersections where the approaching traffic will encounter a YIELD sign at the intersection.

C-20 Standard: 17 The yield-ahead triangle symbol or YIELD AHEAD word pavement marking shall not be used unless a YIELD sign (see Section 2B.08) is in place at the intersection. The yield- ahead symbol marking shall be as shown in Figure 3B-26. Guidance: 18 The International Symbol of Accessibility parking space marking (see Figure 3B-22) should be placed in each parking space designated for use by persons with disabilities. Option: 19 A blue background with white border may supplement the wheelchair symbol as shown in Figure 3B-22. Support: 20 Lane-use arrow markings (see Figure 3B-24) are used to indicate the mandatory or permissible movements in certain lanes (see Figure 3B-27) and in two-way left-turn lanes (see Figure 3B-7). Guidance: 21 Lane-use arrow markings (see Figure 3B-24) should be used in lanes designated for the exclusive use of a turning movement, including turn bays, except where engineering judgment determines that physical conditions or other markings (such as a dotted extension of the lane line through the taper into the turn bay) clearly discourage unintentional use of a turn bay by through vehicles. Lane-use arrow markings should also be used in lanes from which movements are allowed that are contrary to the normal rules of the road (see Drawing B of Figure 3B-13). When used in turn lanes, at least two arrows should be used, one at or near the upstream end of the full-width turn lane and one an appropriate distance upstream from the stop line or intersection (see Drawing A of Figure 3B-11). Option: 22 An additional arrow or arrows may be used in a turn lane. When arrows are used for a short turn lane, the second (downstream) arrow may be omitted based on engineering judgment. 22a Lane-use arrows may be used in the lanes of a divided highway to deter wrong-way movements at the crossing of the divided highway with a crossroad (see Figures 2B-15 and 2B- 16). Guidance: 23 Where opposing offset channelized left-turn lanes exist, lane-use arrow markings should be placed near the downstream terminus of the offset left-turn lanes to reduce wrong-way movements (see Figure 2B-17). Support: 24 An arrow at the downstream end of a turn lane can help to prevent wrong way movements. Standard: 25 Where through lanes approaching an intersection become mandatory turn lanes, lane- use arrow markings (see Figure 3B-24) shall be used and shall be accompanied by standard signs.

C-21 Guidance: 26 Where through lanes approaching an intersection become mandatory turn lanes, ONLY word markings (see Figure 3B-23) should be used in addition to the required lane-use arrow markings and signs (see Sections 2B.19 and 2B.20). These markings and signs should be placed well in advance of the turn and should be repeated as necessary to prevent entrapment and to help the road user select the appropriate lane in advance of reaching a queue of waiting vehicles (see Drawing A of Figure 3B-11). Option: 27 On freeways or expressways where a through lane becomes a mandatory exit lane, lane-use arrow markings may be used on the approach to the exit in the dropped lane and in an adjacent optional through-or-exit lane if one exists. Guidance: 28 A two-way left-turn lane-use arrow pavement marking, with opposing arrows spaced as shown in Figure 3B-7, should be used at or just downstream from the beginning of a two-way left-turn lane. Option: 29 Additional two-way left-turn lane-use arrow markings may be used at other locations along a two-way left-turn lane where engineering judgment determines that such additional markings are needed to emphasize the proper use of the lane. Standard: 30 A single-direction lane-use arrow shall not be used in a lane bordered on both sides by yellow two-way left-turn lane longitudinal markings. 31 Lane-use, lane-reduction, and wrong-way arrow markings shall be designed as shown in Figure 3B-24 and in the “Standard Highway Signs and Markings” book (see Section 1A.11). Option: 32 The ONLY word marking (see Figure 3B-23) may be used to supplement the lane-use arrow markings in lanes that are designated for the exclusive use of a single movement (see Figure 3B- 27) or to supplement a preferential lane word or symbol marking (see Section 3D.01). Standard: 33 The ONLY word marking shall not be used in a lane that is shared by more than one movement. Guidance: 34 Where a lane-reduction transition occurs on a roadway with a speed limit of 45 mph or more, the lane-reduction arrow markings shown in Drawing F in Figure 3B-24 should be used (see Figure 3B-14). Except for acceleration lanes, where a lane-reduction transition occurs on a roadway with a speed limit of less than 45 mph, the lane-reduction arrow markings shown in Drawing F in Figure 3B-24 should be used if determined to be appropriate based on engineering judgment. Option: 35 Lane-reduction arrow markings may be used in long acceleration lanes based on engineering judgment.

C-22 Guidance: 36 Where crossroad channelization or ramp geometrics do not make wrong-way movements difficult, the appropriate lane-use arrow should be placed in each lane of an exit ramp near the crossroad terminal where it will be clearly visible to a potential wrong-way road user (see Figure 2B-18). Option: 37 The wrong-way arrow markings shown in Drawing D in Figure 3B-24 may be placed near the downstream terminus of a ramp as shown in Figures 2B-18 and 2B-19, or at other locations where lane-use arrows are not appropriate, to indicate the correct direction of traffic flow and to discourage drivers from traveling in the wrong direction. 37a The wrong-way arrow marking may be used upstream of the intersection at a divided highway crossing to deter wrong-way movements. They may be used in lieu of or in addition to lane-use arrows. Section 2B.09 YIELD Sign Applications Option: 01 YIELD signs may be installed: A. On the approaches to a through street or highway where conditions are such that a full stop is not always required. B. At the second intersection crossroad of a divided highway crossing or median break functioning as two separate intersections, where the median width at the intersection is 30 feet or greater. In this case, a STOP or YIELD sign may be installed at the entrance to the first intersection roadway of a divided highway crossing, and a YIELD sign may be installed at the entrance to the second intersection roadway. C. For a channelized turn lane that is separated from the adjacent travel lanes by an island, even if the adjacent lanes at the intersection are controlled by a highway traffic control signal or by a STOP sign. D. At an intersection where a special problem exists and where engineering judgment indicates the problem to be susceptible to correction by the use of the YIELD sign. E. Facing the entering roadway for a merge-type movement if engineering judgment indicates that control is needed because acceleration geometry and/or sight distance is not adequate for merging traffic operation. Standard: 02 A YIELD (R1-2) sign shall be used to assign right-of-way at the entrance to a roundabout. YIELD signs at roundabouts shall be used to control the approach roadways and shall not be used to control the circulatory roadway. 03 Other than for all of the approaches to a roundabout, YIELD signs shall not be placed on all of the approaches to an intersection.

C-23 Section 4C.01 Studies and Factors for Justifying Traffic Control Signals Standard: 01 An engineering study of traffic conditions, pedestrian characteristics, and physical characteristics of the location shall be performed to determine whether installation of a traffic control signal is justified at a particular location. 02 The investigation of the need for a traffic control signal shall include an analysis of factors related to the existing operation and safety at the study location and the potential to improve these conditions, and the applicable factors contained in the following traffic signal warrants: Warrant 1, Eight-Hour Vehicular Volume Warrant 2, Four-Hour Vehicular Volume Warrant 3, Peak Hour Warrant 4, Pedestrian Volume Warrant 5, School Crossing Warrant 6, Coordinated Signal System Warrant 7, Crash Experience Warrant 8, Roadway Network Warrant 9, Intersection Near a Grade Crossing 03 The satisfaction of a traffic signal warrant or warrants shall not in itself require the installation of a traffic control signal. Support: 04 Sections 8C.09 and 8C.10 contain information regarding the use of traffic control signals instead of gates and/or flashing-light signals at highway-rail grade crossings and highway-light rail transit grade crossings, respectively. Guidance: 05 A traffic control signal should not be installed unless one or more of the factors described in this Chapter are met. 06 A traffic control signal should not be installed unless an engineering study indicates that installing a traffic control signal will improve the overall safety and/or operation of the intersection. 07 A traffic control signal should not be installed if it will seriously disrupt progressive traffic flow. 08 The study should consider the effects of the right-turn vehicles from the minor-street approaches. Engineering judgment should be used to determine what, if any, portion of the right- turn traffic is subtracted from the minor-street traffic count when evaluating the count against the signal warrants listed in Paragraph 2. 09 Engineering judgment should also be used in applying various traffic signal warrants to cases where approaches consist of one lane plus one left-turn or right-turn lane. The site-specific traffic characteristics should dictate whether an approach is considered as one lane or two lanes. For example, for an approach with one lane for through and right-turning traffic plus a left-turn lane, if engineering judgment indicates that it should be considered a one-lane approach because the traffic using the left-turn lane is minor, the total traffic volume approaching the intersection should be applied against the signal warrants as a one-lane approach. The approach should be considered two lanes if approximately half of the traffic on

C-24 the approach turns left and the left-turn lane is of sufficient length to accommodate all left-turn vehicles. 10 Similar engineering judgment and rationale should be applied to a street approach with one through/left-turn lane plus a right-turn lane. In this case, the degree of conflict of minor-street right-turn traffic with traffic on the major street should be considered. Thus, right-turn traffic should not be included in the minor-street volume if the movement enters the major street with minimal conflict. The approach should be evaluated as a one-lane approach with only the traffic volume in the through/left-turn lane considered. 11 At a location that is under development or construction and where it is not possible to obtain a traffic count that would represent future traffic conditions, hourly volumes should be estimated as part of an engineering study for comparison with traffic signal warrants. Except for locations where the engineering study uses the satisfaction of Warrant 8 to justify a signal, a traffic control signal installed under projected conditions should have an engineering study done within 1 year of putting the signal into stop-and-go operation to determine if the signal is justified. If not justified, the signal should be taken out of stop-and-go operation or removed. 12 For signal warrant analysis, a divided highway crossing that functions as two intersections location with a wide median, even if the median width is greater than 30 feet, should be considered as one intersection. Option: 13 At an intersection with a high volume of left-turn traffic from the major street, the signal warrant analysis may be performed in a manner that considers the higher of the major-street left- turn volumes as the “minor-street” volume and the corresponding single direction of opposing traffic on the major street as the “major-street” volume. 14 For signal warrants requiring conditions to be present for a certain number of hours in order to be satisfied, any four sequential 15-minute periods may be considered as 1 hour if the separate 1-hour periods used in the warrant analysis do not overlap each other and both the major-street volume and the minor-street volume are for the same specific one-hour periods. 15 For signal warrant analysis, bicyclists may be counted as either vehicles or pedestrians. Support: 16 When performing a signal warrant analysis, bicyclists riding in the street with other vehicular traffic are usually counted as vehicles and bicyclists who are clearly using pedestrian facilities are usually counted as pedestrians. Option: 17 Engineering study data may include the following: A. The number of vehicles entering the intersection in each hour from each approach during 12 hours of an average day. It is desirable that the hours selected contain the greatest percentage of the 24-hour traffic volume. B. Vehicular volumes for each traffic movement from each approach, classified by vehicle type (heavy trucks, passenger cars and light trucks, public-transit vehicles, and, in some locations, bicycles), during each 15-minute period of the 2 hours in the morning and 2 hours in the afternoon during which total traffic entering the intersection is greatest. C. Pedestrian volume counts on each crosswalk during the same periods as the vehicular counts in Item B and during hours of highest pedestrian volume. Where young, elderly,

C-25 and/or persons with physical or visual disabilities need special consideration, the pedestrians and their crossing times may be classified by general observation. D. Information about nearby facilities and activity centers that serve the young, elderly, and/or persons with disabilities, including requests from persons with disabilities for accessible crossing improvements at the location under study. These persons might not be adequately reflected in the pedestrian volume count if the absence of a signal restrains their mobility. E. The posted or statutory speed limit or the 85th-percentile speed on the uncontrolled approaches to the location. F. A condition diagram showing details of the physical layout, including such features as intersection geometrics, channelization, grades, sight-distance restrictions, transit stops and routes, parking conditions, pavement markings, roadway lighting, driveways, nearby railroad crossings, distance to nearest traffic control signals, utility poles and fixtures, and adjacent land use. G. A collision diagram showing crash experience by type, location, direction of movement, severity, weather, time of day, date, and day of week for at least 1 year. 18 The following data, which are desirable for a more precise understanding of the operation of the intersection, may be obtained during the periods described in Item B of Paragraph 17: A. Vehicle-hours of stopped time delay determined separately for each approach. B. The number and distribution of acceptable gaps in vehicular traffic on the major street for entrance from the minor street. C. The posted or statutory speed limit or the 85th-percentile speed on controlled approaches at a point near to the intersection but unaffected by the control. D. Pedestrian delay time for at least two 30-minute peak pedestrian delay periods of an average weekday or like periods of a Saturday or Sunday. E. Queue length on stop-controlled approaches. References Harwood, D. W., M. T. Pietrucha, M. D. Wooldridge, R. E. Brydia, and K. Fitzpatrick. 1995. NCHRP Report 375: Median Intersection Design. Transportation Research Board, Washington, D.C. Khazraee, S. H., and H. G. Hawkins, Jr. 2015. “Criteria for Determining Number of Intersections at Divided Highway Junctions: Recommended Changes to Manual on Uniform Traffic Control Devices.” Transportation Research Record: Journal of the Transportation Research Board, No. 2492, Transportation Research Board, Washington, D.C., p. 23. Khazraee, S. H., and H. G. Hawkins, Jr. 2016. “Revised Guidelines for Designing Median Openings to Accommodate Simultaneous Left Turns.” ASCE Journal of Transportation Engineering, Vol. 142, No. 10.

Abbreviations and acronyms used without definitions in TRB publications: A4A Airlines for America AAAE American Association of Airport Executives AASHO American Association of State Highway Officials AASHTO American Association of State Highway and Transportation Officials ACI–NA Airports Council International–North America ACRP Airport Cooperative Research Program ADA Americans with Disabilities Act APTA American Public Transportation Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials ATA American Trucking Associations CTAA Community Transportation Association of America CTBSSP Commercial Truck and Bus Safety Synthesis Program DHS Department of Homeland Security DOE Department of Energy EPA Environmental Protection Agency FAA Federal Aviation Administration FAST Fixing America’s Surface Transportation Act (2015) FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FRA Federal Railroad Administration FTA Federal Transit Administration HMCRP Hazardous Materials Cooperative Research Program IEEE Institute of Electrical and Electronics Engineers ISTEA Intermodal Surface Transportation Efficiency Act of 1991 ITE Institute of Transportation Engineers MAP-21 Moving Ahead for Progress in the 21st Century Act (2012) NASA National Aeronautics and Space Administration NASAO National Association of State Aviation Officials NCFRP National Cooperative Freight Research Program NCHRP National Cooperative Highway Research Program NHTSA National Highway Traffic Safety Administration NTSB National Transportation Safety Board PHMSA Pipeline and Hazardous Materials Safety Administration RITA Research and Innovative Technology Administration SAE Society of Automotive Engineers SAFETEA-LU Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (2005) TCRP Transit Cooperative Research Program TDC Transit Development Corporation TEA-21 Transportation Equity Act for the 21st Century (1998) TRB Transportation Research Board TSA Transportation Security Administration U.S.DOT United States Department of Transportation

TRA N SPO RTATIO N RESEA RCH BO A RD 500 Fifth Street, N W W ashington, D C 20001 A D D RESS SERV ICE REQ U ESTED N O N -PR O FIT O R G . U .S. PO STA G E PA ID C O LU M B IA , M D PER M IT N O . 88 ISBN 978-0-309-39056-9 9 7 8 0 3 0 9 3 9 0 5 6 9 9 0 0 0 0 Traffic Control D evices and M easures for D eterring W rong-W ay M ovem ents N CH RP Research Report 881 TRB