National Academies Press: OpenBook

Pavement Markings--Design and Typical Layout Details (2006)

Chapter: Chapter Four - Pavement Markings at Interchanges

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Suggested Citation:"Chapter Four - Pavement Markings at Interchanges." National Academies of Sciences, Engineering, and Medicine. 2006. Pavement Markings--Design and Typical Layout Details. Washington, DC: The National Academies Press. doi: 10.17226/13947.
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Suggested Citation:"Chapter Four - Pavement Markings at Interchanges." National Academies of Sciences, Engineering, and Medicine. 2006. Pavement Markings--Design and Typical Layout Details. Washington, DC: The National Academies Press. doi: 10.17226/13947.
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Suggested Citation:"Chapter Four - Pavement Markings at Interchanges." National Academies of Sciences, Engineering, and Medicine. 2006. Pavement Markings--Design and Typical Layout Details. Washington, DC: The National Academies Press. doi: 10.17226/13947.
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Suggested Citation:"Chapter Four - Pavement Markings at Interchanges." National Academies of Sciences, Engineering, and Medicine. 2006. Pavement Markings--Design and Typical Layout Details. Washington, DC: The National Academies Press. doi: 10.17226/13947.
×
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Suggested Citation:"Chapter Four - Pavement Markings at Interchanges." National Academies of Sciences, Engineering, and Medicine. 2006. Pavement Markings--Design and Typical Layout Details. Washington, DC: The National Academies Press. doi: 10.17226/13947.
×
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Suggested Citation:"Chapter Four - Pavement Markings at Interchanges." National Academies of Sciences, Engineering, and Medicine. 2006. Pavement Markings--Design and Typical Layout Details. Washington, DC: The National Academies Press. doi: 10.17226/13947.
×
Page 41
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Suggested Citation:"Chapter Four - Pavement Markings at Interchanges." National Academies of Sciences, Engineering, and Medicine. 2006. Pavement Markings--Design and Typical Layout Details. Washington, DC: The National Academies Press. doi: 10.17226/13947.
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Figures 3B-8 and 3B-9 (see Appendix A) show examples of the pavement markings that are used in the gore areas of entrance and exit ramps, including channelizing lines and optional chevron markings. Figure 10 shows an example of the use of diagonal lines within the paved gore of an exit ramp. 2003 MUTCD Provisions Paragraph 1 of Section 3B.05 contains the following stan- dard: “A channelizing line shall be a wide or double solid white line.” A wide line is 8 to 12 in. wide. A double line consists of two parallel lines separated by a discernible space. Paragraph 6 of Section 3B.05 contains the following sup- port: “Channelizing lines at entrance ramps as shown in Fig- ure 3B-9 promote reasonably safe and efficient merging with the through traffic.” Paragraph 9 of Section 3B.05 contains the following guid- ance: “For entrance ramps, a channelizing line should be placed along the side of the neutral area adjacent to the ramp lane.” Paragraph 11 of Section 3B.05 contains the following option: “For entrance ramps with a tapered acceleration lane, lane line markings may be placed to extend the channelizing line, but not beyond a point where the tapered lane meets the near side of the through traffic lane as shown in Figure 3B-9.” Paragraph 5 of Section 3B.05 contains the following sup- port: “Channelizing lines at exit ramps as shown in Figure 3B-8 define the neutral area, direct exiting traffic at the proper angle for smooth divergence from the main lanes into the ramp, and reduce the probability of colliding with objects adjacent to the roadway.” Paragraph 7 of Section 3B.05 contains the following stan- dard: “For exit ramps, channelizing lines shall be placed along the sides of the neutral area adjacent to the through traffic lane and the ramp lane.” This standard is universally followed. Paragraph 8 of Section 3B.05 contains the following option: “White chevron markings may be placed in the neu- tral area for special emphasis as shown in Figure 3B-8.” Although this paragraph immediately follows a paragraph regarding exit ramps and although Figure 3B-9 does not mention the option of using chevrons in the paved gores for entrance ramps, there are no provisions in the MUTCD that 36 specifically prohibit the use of chevrons in the paved gores for entrance ramps. Figure 3B-9 provides examples of entrance ramps with parallel and tapered acceleration lanes. Chevrons are not shown in the paved gores. Wide channelizing lines that begin at the upstream end of the paved gore are shown on both sides of the paved gore for the parallel acceleration lane example. In the example with the tapered acceleration lane, a wide channelizing line that begins at the upstream end of the paved gore is shown only on the ramp side of the paved gore. The wide channelizing line ends before the down- stream end of the gore and a broken lane line is used to define the remainder of the ramp side of the paved gore. Figure 3B-8 provides examples of exit ramps with paral- lel and tapered deceleration lanes. Chevrons are shown in the paved gores, but a note indicates that they are optional. The note for Drawing “c” indicates that the markings within the paved gore may also be diagonal lines rather than chevrons. Wide channelizing lines that end at the downstream end of the paved gore are shown on both sides of the paved gores. In the example with the tapered deceleration lane, an optional dotted extension of the right edge line is shown upstream from the upstream end of the paved gore. Figure 3B-10 pro- vides an example of an exit ramp where chevrons are not shown in the paved gore (see Appendix A for figures). ENTRANCE RAMP GORES Width of Channelizing Lines (43 agencies) The following widths are explicitly specified in the design standards for the channelizing lines associated with entrance ramps: UT—4 in. for parallel acceleration lanes and 8 in. for tapered acceleration lanes WV—6 to 8 in. CA, CO, CT, FL, HI, IL, IN, IA, KS, LA, MA, MN, MO, MT, ND, OK, OR, PA, TN, TX, VA, WA, WI, WY, PR, NYC—8 in. AL, NC, OH—8 in. or 12 in. SC—8 in. for primary and secondary highways and 12 in. for expressways and freeways GA, MD—10 in. AZ, DE, MI, MS, NE, NH, NY, RI, VT—12 in. CHAPTER FOUR PAVEMENT MARKINGS AT INTERCHANGES

37 Upstream End of Channelizing Line on Left-Hand Side of Entrance Ramp (42 agencies) The following points (measured upstream from the upstream end of the paved gore) are explicitly specified in the design standards for the upstream end of the channelizing line on the left-hand side of the entrance ramp: AL, CA, FL, GA, IN, IA, KS, LA, MA, MI, MN, MS, MO, MT, NY, ND, OH, OR, TX, UT, VT, VA, WA, WY, PR—0 ft CO—just upstream NH—5 ft CT—20 ft WV—25 ft HI—40 ft AZ, DE, IL, MD, PA, TN, WI—50 ft NC—where the paved shoulders portion of the gore starts OK—downstream end of the paved shoulder on the ramp NE, SC, NYC—unspecified distance upstream. Downstream End of Channelizing Line on Left-Hand Side of Entrance Ramp (26 agencies) The design standards consistently show the channelizing line on the left-hand side of an entrance ramp extending to the downstream end of the paved gore (where the ramp and the mainline roadway become adjacent to one another) when a parallel acceleration lane is used. The following points are explicitly specified in the design standards for the downstream end of the channelizing line FIGURE 10 Examples of use of diagonal lines in paved gores (Source: West Virginia DOT 1994 Standard Details Book, Sheet TEM-1).

on the left-hand side of an entrance ramp when a tapered acceleration lane is used: NC—upstream end of the paved gore ND—195 ft downstream from the upstream end of the paved gore WV—midpoint of the paved gore WY—point where ramp and mainline roadway are the samedistanceapart as the width of the mainline shoulder CA, CO, GA, HI, IL, MN, MT, NY, OH, TN, WA—point where ramp and mainline roadway are 6 ft apart AZ, NH—point where ramp and mainline roadway are 5 ft apart UT—point where ramp and mainline roadway are 3 ft apart IA—point where ramp and left edge line of a 2-lane main- line roadway are 28 ft apart IN, OK, PA, VT, WI, PR—downstream end of the paved gore. Extension of Channelizing Line on Left-Hand Side of Entrance Ramp (26 agencies) The design standards consistently show the channelizing line extension on the left-hand side of an entrance ramp extending to the downstream end of the paved gore (where the left-hand side of the ramp reaches the edge of the mainline roadway) when a tapered acceleration lane is used. The following widths are used for the channelizing line extensions on the left-hand side of entrance ramps when a tapered acceleration lane is used: CA, CO, IA, MT, NC, ND, WY—4 in. GA—5 in. AZ, NH—6 in. The following patterns are used for the channelizing line extensions on the left-hand side of entrance ramps when a tapered acceleration lane is used: CA—7-ft segments with 17-ft gaps AZ, CO, GA, HI, IL, IA, MT, NH, NC, ND, OH, TN, UT, WV, WY—10-ft segments with 30-ft gaps. The design standards for New York show a partial barrier line (a 6-in.-wide solid line on the gore side and a 6-in.-wide broken line with 10-ft segments and 30-ft gaps on the ramp side) being used to extend the channelizing line on the left- hand side of the entrance ramp. Use Versus Non-Use of Channelizing Line on Right-Hand Side of Mainline Roadway (42 agencies) The design standards for 26 agencies (AL, AZ, DE, FL, HI, IN, KS, LA, MD, MA, MI, MS, MO, MT, NE, NH, NC, OK, 38 OR, PA, TN, TX, VT, VA, PR, and NYC) show that the use of a channelizing line on the right-hand side of the mainline roadway is required. The design standards for seven agencies (CA, CO, CT, OH, SC, UT, and WA) state that channelizing lines are not used on the right-hand side of the mainline roadway. The design standards for nine agencies (GA, IL, IA, MN, NY, ND, WV, WI, and WY) state that channelizing lines are not used on the right-hand side of the mainline roadway when a tapered acceleration lane is used, but are used on the right-hand side of the mainline roadway when a parallel acceleration lane is used. Upstream End of Channelizing Line on Right-Hand Side of Mainline Roadway (34 agencies) The following points (measured upstream from the upstream end of the paved gore) are explicitly specified in the design standards for the upstream end of the channelizing line on the right-hand side of the mainline roadway: AL, FL, GA, IL, IN, IA, KS, LA, MA, MI, MN, MS, MO, MT, NY, ND, OK, OR, TX, VT, VA, WY, PR—0 ft NH—5 ft WV—25 ft HI—40 ft DE—less than 50 ft (the point on the right edge line where a perpendicular line would line up with the upstream end of the gore striping on the ramp) AZ, MD, PA, TN—50 ft NC—where the paved shoulders portion of the gore starts NE, NYC—unspecified distance prior. Use Versus Non-Use of Chevrons Within Paved Gore (44 agencies) The design standards for four agencies (FL, OK, TN, and PR) show that the use of chevrons within the paved gores of entrance ramps is required. The design standards for Ten- nessee note that if the gore area is so short that at least five chevrons cannot be placed within the gore, the chevrons are omitted from the gore area. The design standards for three agencies (KY, MD, and VA) show that the use of chevrons within the paved gores of entrance ramps is optional. The design standards for 36 agencies (AL, AZ, CA, CO, CT, DE, GA, HI, IL, IA, KS, LA, MA, MI, MN, MS, MO, MT, NE, NH, NY, NC, ND, OH, OR, PA, RI, SC, TX, UT, VT, WA, WV, WI, WY, and NYC) state or show that chevrons are not used within the paved gores of entrance ramps. The design standards for Indiana state that chevrons are not used within the paved gores of entrance ramps when a parallel

39 acceleration lane is used, but are used within the paved gores of entrance ramps when a tapered acceleration lane is used. Width of Chevrons Within Paved Gore (7 agencies) The design standards for the seven agencies that specify a width for the chevrons (at a forward angle of 45°) that are placed within the paved gores of entrance ramps use the fol- lowing widths: OK—8 in. IN—12 in. when the posted speed limit is 45 mph or less and 24 in. when the posted speed limit is more than 45 mph TN, PR—12 in. MD—16 in. FL—18 in. VA—24 in. Spacing of Chevrons Within Paved Gore (7 agencies) The design standards for the seven agencies that specify the spacing (measured along the edge line of the mainline road- way) for the chevrons that are placed within the paved gores of entrance ramps use the following spacings: PR—7 ft (shown as 2.0 m) VA—8 ft OK—10 ft IN—20 ft when the posted speed limit is 45 mph or less and 40 ft when the posted speed limit is more than 45 mph FL—20 ft TN—20 ft (until the width of the gore becomes 6 ft) MD—50 ft for blunt angle gores and up to 100 ft for sharp angle gores. Other Considerations for Entrance Ramps (6 agencies) The design standards for Maryland show that the last chevron stripe is placed 50 ft upstream from the point where the gore width becomes 1 ft wide. The design standards for Massachusetts do not show pavement markings within the paved portion of the gore, but “rubble block” is shown as an option in this area unless travel is sometimes permitted in the breakdown lane (shoulder) of the mainline roadway. The design standards for Michigan show that at the down- stream end of the gore the two 12-in.-wide channelizing lines are side-by-side, thus resulting in a 24-in.-wide line. The design standards for North Carolina show a 4- to 6-in.-wide dotted line (2-ft segments with 13-ft gaps) being placed along the right-hand side of the adjacent mainline lane from the downstream end of the gore to the downstream end of the taper for the acceleration lane. Three through arrows at a 45° angle are placed at 100-ft intervals ending at the downstream end of the acceleration lane. The design standards for Tennessee show that for tapered acceleration lanes a 6-in.-wide dotted line (2-ft segments with 4-ft gaps) is placed along the right-hand side of the adja- cent mainline lane from the downstream end of the gore to the downstream end of the entrance ramp. The design standards for West Virginia show for tapered acceleration lanes a 4-in.-wide dotted line (2-ft segments with 13-ft gaps) being placed along the right-hand side of the adjacent mainline lane from the downstream end of the gore to the downstream end of the taper for the acceleration lane. EXIT RAMP GORES Width of Channelizing Lines (44 agencies) The following widths are explicitly specified in the design standards for the channelizing lines associated with exit ramps: WV—6 to 8 in. CA, CO, CT, FL, HI, IL, IN, IA, KS, LA, MA, MN, MO, MT, ND, OK, OR, PA, TN, TX, UT, VA, WA, WI, WY, PR, NYC—8 in. AL, NC, OH—8 in. or 12 in. SC—8 in. for primary and secondary highways and 12 in. for expressways and freeways GA, MD—10 in. AZ, DE, MI, MS, NE, NV, NH, NY, RI, VT—12 in. Use Versus Non-Use of Channelizing Line on Right-Hand Side of Mainline Roadway (44 agencies) The design standards consistently show that the use of a channelizing line on the right-hand side of the mainline road- way is required for exit ramps. Upstream End of Channelizing Lines for Exit Ramps with Tapered Deceleration Lanes (44 agencies) The design standards consistently show that the upstream end of channelizing lines for exit ramps with tapered decel- eration lanes to be the point where the full width of the exit ramp first becomes available. Downstream End of Channelizing Line on Left-Hand Side of Exit Ramp (43 agencies) The following points (measured downstream from the down- stream end of the paved gore) are explicitly specified in the

design standards for the downstream end of the channelizing line on the left-hand side of the entrance ramp: AL, CA, FL, GA, IN, IA, MA, MI, MN, MO, MT, NV, NY, NC, OH, OR, PA, SC, UT, VT, VA, WA, WY, PR—0 ft KS—0 ft for parallel deceleration lanes and an unspecified distance downstream for tapered deceleration lanes NH—5 ft CT—20 ft HI—40 ft ND—40 ft for parallel deceleration lanes and 240 ft from the upstream end of the paved gore for tapered decel- eration lanes AZ, DE, IL, MD, TN, WI—50 ft TX—at the downstream end of the paved shoulder por- tion of the gore CO—at the location of the Exit Gore sign WV—25 ft downstream from the location of the Exit Gore sign LA—at the point where the shoulder returns to normal width OK—at the point where the paved shoulder begins MS—at the point where the curvature on the ramp changes NE, NYC—unspecified distance downstream. Downstream End of Channelizing Line on Right-Hand Side of Mainline Roadway (43 agencies) The following points (measured downstream from the down- stream end of the paved gore) are explicitly specified in the design standards for the downstream end of the channelizing line on the right-hand side of the mainline roadway: AL, CA, FL, GA, IN, IA, MA, MI, MN, MO, MT, NV, NY, NC, OK, OR, UT, VT, WA, WY, PR—0 ft ND—0 ft for parallel deceleration lanes and 200 ft from the upstream end of the paved gore for tapered deceleration lanes NH—5 ft CT—20 ft HI—40 ft DE—less than 50 ft (the point on the right edge line where a perpendicular line would line up with the downstream end of the gore striping on the ramp) AZ, IL, MD, PA, TN, WI—50 ft VA—150 ft TX—at the downstream end of the paved shoulder portion of the gore CO—at the location of the Exit Gore sign WV—25 ft downstream from the location of the Exit Gore sign OH—at the point where the paved shoulder ends LA—at the point where the shoulder returns to normal width 40 KS—at the point where the extra roadway paving on the right of the right edge line of the mainline roadway ends (diagonal lines that are 12 in. wide at a 30° angle at 40-ft spacing are placed in the extra roadway paving) MS—at the point well beyond the downstream end of the gore where the portion of the shoulder that is paved with mainline roadway paving (as opposed to shoulder thickness paving) becomes only 6 ft wide NE, SC, NYC—unspecified distance downstream. Use Versus Non-Use of Chevrons or Diagonal Lines Within the Paved Gore (45 agencies) The design standards for 11 agencies (AZ, FL, HI, IN, KS, LA, OK, RI, TN, PR, and NYC) show that the use of chevrons within the paved gores of exit ramps is required. The design standards for Indiana state that when ramp volumes are low, diagonal lines may be used instead of chevrons. The design standards for Tennessee note that if the gore area is so short that at least five chevrons cannot be placed within the gore the chevrons are omitted from the gore area. The design standards for New York State show that the use of chevrons is required within the paved gores of exit ramps at major exits, and the use of diagonal lines is required within the paved gores of exit ramps at minor exits. The design standards for Texas and West Virginia show that the use of diagonal lines within the paved gores of exit ramps is required. The design standards for Massachusetts show that the use of diagonal lines within the paved gores of exit ramps is required unless travel is sometimes permitted in the break- down lane (shoulder) of the mainline roadway. The design standards for five agencies (CO, CT, KY, MD, and VA) state or show that the use of chevrons within the paved gores of exit ramps is optional. The design standards for four agencies (IL, OH, VT, and WI) state or show that the use of diagonal lines within the paved gores of exit ramps is optional. The design standards for Pennsylvania state or show that the use of chevrons or diagonal lines within the paved gores of exit ramps is optional. The design standards for Oregon state or show that chevrons or diagonal lines are not used within the paved gores of exit ramps with parallel deceleration lanes, but the use of chevrons or diagonal lines within the paved gores of exit ramps with tapered deceleration lanes is optional. The design standards for 18 agencies (CA, DE, GA, IA, MI, MN, MS, MO, MT, NE, NV, NH, NC, ND, SC, UT,

41 WA, and WY) state or show that chevrons or diagonal lines are not used within the paved gores of exit ramps. The design standards for Alabama show that chevrons are not used within the paved gores of exit ramps unless a recov- ery area or a parallel recovery lane is provided. Width of Chevrons or Diagonal Lines Within the Paved Gore (25 agencies) The design standards for the 25 agencies that specify a width for the chevrons (at a forward angle of 45°) or diagonal lines (at a forward angle of 45° from the right edge line of the main- line lane unless otherwise stated—they do not intersect the left edge line of the ramp at a 45° forward angle) that are placed within the paved gores of exit ramps use the following widths: CO, OK—8 in. AZ, HI, IL, KS, OR, RI, TN, VT, PR—12 in. MA—12 in. at a 3-to-1 slope forward angle from the right edge line of the mainline lane (they do not intersect the left edge line of the ramp at a forward angle) IN—12 in. when the posted speed limit is 45 mph or less and 24 in. when the posted speed limit is more than 45 mph MD, NYC—16 in. FL—18 in. TX—typically 24 in., but no less than 12 in. AL, LA, NY, OH, PA, VA, WV, WI—24 in. Spacing of Chevrons or Diagonal Lines Within Paved Gore (23 agencies) The design standards for the 23 agencies that specify the spacing (measured along the edge line of the mainline road- way) for the chevrons or diagonal lines that are placed within the paved gores of exit ramps use the following spacings: VT—7 ft PR—7 ft (shown as 2.0 m) VA—8 ft WV—8 to 12 ft WI—8 to 25 ft OK—10 ft IL—10 to 20 ft NY—11 ft (shown as 3.3 m) LA—12 ft for posted mainline speed limits of 45 mph or less, 18 ft for 50 or 55 mph, and 24 ft for 65 mph OH—12 ft for the first 48 ft, 24 ft for the next 48 ft, and 48 ft thereafter AL—15 ft in urban areas and 25 ft in rural areas PA—16 ft MA—16 ft (shown as 5 m) FL, HI, RI, TX—20 ft TN—20 ft (starting at the point where the gore becomes 6 ft wide) IN—20 ft when the posted speed limit is 45 mph or less and 40 ft when the posted speed limit is more than 45 mph CO—25 ft (starting at the point where the gore becomes 6 ft wide) AZ, KS—40 ft MD—50 ft for blunt angle gores and up to 100 ft for sharp angle gores. Use Versus Non-Use of Dotted Line in Departure Area of Tapered Deceleration Lane (41 agencies) The design standards for 20 agencies (AL, CO, CT, GA, HI, IN, IA, KS, MI, NH, NC, ND, OH, OK, TN, TX, UT, VT, WV, and WI) show that the use of a dotted line to extend the right edge line of the mainline roadway to the upstream end of the paved gore of exit ramps with tapered deceleration lanes is required. The design standards for New York City show that the use of a dotted line to extend the right edge line of the mainline roadway to the upstream end of the paved gore of exit ramps with tapered deceleration lanes is typically used. The design standards for nine agencies (AZ, IL, MS, MT, NY, OR, PA, WY, and PR) show that the use of a dotted line to extend the right edge line of the mainline roadway to the upstream end of the paved gore of exit ramps with tapered deceleration lanes is optional. The design standards for 11 agencies (CA, FL, LA, MD, MN, MO, NE, NV, SC, VA, and WA) state or show that dot- ted lines are not used to extend the right edge line of the mainline roadway to the upstream end of the paved gore of exit ramps with tapered deceleration lanes. Width of Dotted Line in Departure Area of Tapered Deceleration Lane (28 agencies) The following widths are used for the dotted line in the departure area of exit ramps with tapered deceleration lanes: AL, CO, HI, IL, IN, IA, MT, ND, OK, TX, UT, VT, WV, WI, WY—4 in. NC, OH—4 to 6 in. GA—5 in. AZ, CT, KS, MI, MS, NH, NY, TN—6 in. PA, NYC—8 in. Type of Dotted Line in Departure Area of Tapered Deceleration Lane (28 agencies) The following patterns are used for the dotted line in the departure area of exit ramps with tapered deceleration lanes: AL, AZ, CO, IA, KS, MT, OH, PA, TN, TX, VT, NYC— 2-ft segments with 4-ft gaps

GA, ND, OR, UT, WY—2-ft segments with 6-ft gaps HI, IN—2-ft segments with 8-ft gaps CT, NH, NY—2-ft segments with 10-ft gaps MS—2-ft segments with 12-ft gaps NC, WV—2-ft segments with 13-ft gaps OK, WI—3-ft segments with 12-ft gaps MI—5-ft segments with 20-ft gaps. The design standards for Ohio show that a 4- to 6-in.-wide broken lane line (10-ft segments with 30-ft gaps) is placed from the point where a full lane width first becomes available to the upstream end of the gore. An optional 4- to 6-in.-wide dotted line (2-ft segments with 4-ft gaps) may be placed along the right-hand side of the adjacent mainline lane from the upstream end of the ramp to the upstream end of the bro- ken lane line. The design standards for Oklahoma show that a 4-in.- wide dotted line (3-ft segments with 12-ft gaps) followed by a 4-in.-wide broken lane line is placed along the right-hand side of the adjacent mainline lane from the upstream end of the exit ramp to the upstream end of the gore. Other Considerations for Exit Ramps (5 agencies) The design standards for Alabama show that for exit ramps with a tapered deceleration lane and a parallel recovery lane, diagonal 12-in.-wide lines at 20-ft intervals in urban areas and 30- to 40-ft intervals in rural areas are used within the right shoulder of the parallel recovery lane for the recovery 42 lane’s entire length and within the left shoulder of the ramp for a distance of 80 ft beyond the point where the paved por- tion of the gore ends. For exit ramps with a recovery area, diagonal 12-in.-wide lines at 20-ft intervals in urban areas and 30- to 40-ft intervals in rural areas are used within the right shoulder of the mainline roadway for a distance of at least 320 ft beyond the point where the paved portion of the gore ends and within the left shoulder of the ramp for a dis- tance of 80 ft beyond the point where the paved portion of the gore ends. The design standards for Florida show that diagonal 18-in.- wide cross-hatching is placed beyond the gore on the right shoulder of the mainline roadway until the shoulder width returns to its normal width. The design standards for Maryland show that the first chevron stripe is placed 50 ft downstream from the point where the gore width becomes 1 ft. The design standards for Michigan show that at the up- stream end of the gore, the two 12-in.-wide channelizing lines are side-by-side, thus resulting in a 24-in.-wide line. The design standards for Washington State show that raised pavement markers forming diagonal lines that point at a 45° forward angle from the right edge line of the mainline lane (they do not intersect the left edge line of the ramp at a 45° forward angle) may be placed within the paved portion of the gore to increase visibility.

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TRB’s National Cooperative Highway Research Program (NCHRP) Synthesis 356: Pavement Markings—Design and Typical Layout Details identifies variations in pavement marking designs, practices, and policies, as provided by 48 of 50 state departments of transportation, and transportation agencies from the District of Columbia, Puerto Rico and four cities.

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