Cover Image

Not for Sale



View/Hide Left Panel
Click for next page ( 24


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 23
23 AR, NE, UT, WV, HI--12 in. Edge of island Chevron CT--at least 12 in. CA, ME, MN--12 to 18 in. in urban areas and 18 to 24 in. in rural areas OR, PA--12 to 24 in. KY--12 or 24 in. TUC--12 in., but 24 in. wide on approaches controlled by STOP signs with speed limits of 45 mph or more DE--16 in. MD--16 in. for approach speed limits of 35 mph or less and 24 in. for approach speed limits more than 35 mph AZ, NH--18 in. WI--typically 18 in., but can vary from 12 to 24 in. NY--18 in., but designer may also specify 12 or 24 in. AL, CO, FL, ID, IN, IA, KS, LA, MI, MO, MT, NV, NC, ND, OH, OK, SC, SD, TN, TX, VT, VA, WY, NYC--24 in. Placement of Stop Lines (38 agencies) (a) Right-turn channelizing island using pavement markings only The design standards for the 38 agencies that specify a stop Edge of island diagonal lines line placement use the following distances from the adjacent crosswalk: MI, MO, NE, NY, OK, PA, SD, WA--4 ft NH, ND, TX, UT, TUC--typically 4 ft island AZ, AR, CA, CO, CT, FL, ID, IN, IA, KY, LA, ME, MD, MT, NV, NC, SC, TN, VT, VA, WI--at least 4 ft WY--4 to 30 ft NYC--5 ft (and STOP messages are placed in approach lanes such that the top of the letters is 10 ft upstream Chevrons from the stop line) AL, KS--at least 5 ft. RIGHT-TURN CHANNELIZING ISLANDS Figure 8 shows examples of right-turn channelizing islands and their associated pavement markings. (b) Right-turn channelizing island 2003 MUTCD Provisions using a raised island FIGURE 8 Examples of right-turn channelizing islands. Paragraph 2 of Section 3B.05 contains the following option: "Channelizing lines may be used to form channelizing islands where traffic traveling in the same direction is per- Width of Lines That Mark the Edges of Right-Turn mitted on both sides of the island." Channelizing Islands (18 agencies) Paragraph 3 of Section 3B.05 contains the following stan- The design standards for the 18 agencies that specify a line dard: "Other pavement markings in the channelizing island width for the channelizing lines that mark the edges of right- area shall be white." Thus, the color of the markings in chan- turn channelizing islands use the following widths: nelizing islands is specified, but not their use, width, or pattern. PA--4 in. Paragraph 9 of Section 3B.10 contains the following MI--6 in. for painted islands and 12 in. for approaches to option: "If traffic can pass either to the right or left of the raised islands obstruction, additional white markings may be placed in the WV--6 in. to 8 in. neutral area between the channelizing lines as shown in Fig- AK, AR, CO, FL, GA, HI, IN, IA, MT, OK, UT, ure 3B-13" (see Appendix A for figures). WY--8 in.

OCR for page 23
24 WI--8 in. on approaches to raised islands only (the lines IL--10 ft for speed limits less than 30 mph, 15 ft for speed extend only 5 ft beyond the nose of the island) limits from 30 to 45 mph, and 20 ft for speed limits TN--8 in. if the area of the island is 400 ft2 or less or if more than 45 mph (in all of these cases, if the recom- the island is raised, and 24 in. if the area of the painted mended spacing does not provide at least five 12-in.- island is more than 400 ft2 wide diagonal lines in the area being marked, the spac- VT--48 in. if the area of the island is 450 ft2 or more (if ing from the next lowest speed range should be used) the area of the island is less than 450 ft2, the island is OH--12 ft painted in its entirety). GA--15 ft HI, IN, IA, MI--20 ft NC--equal in feet to the posted speed limit in mph. Width of Lines Within Right-Turn Channelizing Islands (18 agencies) Other Considerations Regarding Right-Turn The design standards for the 18 agencies that specify a line Channelizing Islands (9 agencies) width for the diagonal lines or chevrons within right-turn channelizing islands use the following widths: The design standards for Arkansas, Colorado, Vermont, and Wyoming specify that no diagonal lines or chevrons be used MI--6 in. when the speed is 45 mph or less and 12 in. within right-turn channelizing islands. when the speed is more than 45 mph IA, NC, OK, UT--8 in. The design standards for Colorado show raised right-turn CA, HI, IN, RI, WV, DC, CLT--12 in. channelizing islands being marked by 8-in.-wide solid lines TN--12 in. if area of island is 400 ft2 or less or if island is on both sides of the gore area leading up to the island, and raised and more than 6 ft of pavement width exists along the left edge line of the right-turn lane from the point between the edge line and the raised island, otherwise where the island ends to the point where the line intersects no markings are used within the island the right edge line of the intersecting roadway. The rest of the AK, FL--18 in. raised island is surrounded by 4-in.-wide edge lines. There GA, OH, SC--24 in. are no markings between the raised island and the 4-in.-wide edge lines or 8-in.-wide solid lines. Spacing of Lines Within Right-Turn Channelizing The design standards for Montana state that diagonal lines Islands (16 agencies) or chevrons are not used on the paved portion between the edge lines and raised islands. The curbs of the raised right- The design standards for the 16 agencies that specify the turn channelizing islands are painted yellow. spacing (the unmarked gap between the nearest edges of the lines) of the diagonal lines or chevrons within right-turn The design standards for Oklahoma and Pennsylvania channelizing islands use the following spacings: note that diagonal lines or chevrons are not used on the paved portion between the edge lines and raised islands. DC--5 ft SC, WV--6 ft The design standards for Oregon state that diagonal lines AK--7 ft or chevrons are optional in right-turn channelizing islands. FL, OK, UT--10 ft TN--10 ft if area of island is 400 ft2 or less or if island is The design standards for Utah show that diagonal lines or raised and more than 6 ft of pavement width exists chevrons are only placed in the painted island area before the between the edge line and the raised island, otherwise raised portion of the island and in the painted island area after no markings are used within the island the raised portion of the island.