Cover Image

Not for Sale



View/Hide Left Panel
Click for next page ( 14


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 13
13 Design of Turn Arrow Symbols (38 agencies) turn lanes at an intersection show a normal solid lane line between the two turn lanes. Drawing "b" in Figure 3B-21 in the 2003 MUTCD shows a design for a Turn Lane-Use Arrow that is 8 ft long. This same Paragraphs 3 and 4 of Section 3B.04 contain the follow- 8-ft-long and 6-ft 4-in.-wide turn arrow design is shown in ing standards: "Where crossing the lane line markings with greater detail on Page 10-10 of the 2004 Standard Highway care is permitted, the lane line markings shall consist of a Signs Book. The pattern for an optional narrow elongated turn normal [4- to 6-in.-wide] broken white line. Where crossing arrow is shown on Page 10-11 of the 2004 Standard Highway the lane line markings is discouraged, the lane line markings Signs Book; however, exact dimensions are not provided. shall consist of a normal [4- to 6-in.-wide] solid white line." The design standards for 36 agencies consistently show Paragraphs 5 and 6 of Section 3B.04 contain the follow- turn arrow symbol designs that are similar to the 8-ft-long ing options: "Solid white lane line markings may be used to turn arrow shown in Figure 3B-21 in the 2003 MUTCD and separate through traffic lanes from auxiliary lanes, such as on Page 10-10 of the 2004 Standard Highway Signs Book. uphill truck lanes, left- or right-turn lanes, and preferential The design standards for 5 of these 36 agencies (CA, HI, OH, lanes. They may also be used to separate traffic lanes approach- OR, and NYC) also show that narrow elongated lane use ing an intersection. Wide [8- to 12-in.-wide] solid lane line arrows that are similar to the turn arrow shown on Page 10- markings may be used for greater emphasis." 11 of the Standard Highway Signs Book are available for use. The design standards for one of these 36 agencies (IL) show that a shorter, 6-ft-long turn arrow that is similar to the shape Type of Lane Line Between the Two Lanes of the turn arrow shown in Figure 3B-21 of the 2003 MUTCD of Dual Turn Lanes (11 agencies) is used in urban areas. Except for the three agencies listed here, the design standards consistently show a solid lane line between the two turn lanes. The design standards for two agencies (PA and WA) show that the 8-ft-long turn arrow that is similar to the turn arrow The design standards for Maryland and Washington State shown in Figure 3B-21 of the 2003 MUTCD is not used. An require that the lane line between the two turn lanes is a bro- elongated 12-ft-long turn arrow that is similar to the turn ken line (10-ft segments with 30-ft gaps) that starts at the stop arrow shown on Page 10-11 of the Standard Highway Signs line and ends at the upstream end of the full-width turn lanes. Book is the only style of turn arrow that is available for use. The design standards for North Carolina require that the LANE LINES FOR DUAL TURN LANES solid lane line starts at the stop line and ends at the midpoint of the full-width turn lanes. From the midpoint to the up- Figure 4 illustrates some of the characteristics of dual turn stream end of the full-width turn lanes, a broken lane line lanes and their associated pavement markings (see Appendix (10-ft segments with 30-ft gaps) is used. A for figures). Width of Lane Line Between the Two Lanes 2003 MUTCD Provisions of Dual Turn Lanes (7 agencies) The MUTCD does not require or recommend a specific type The following widths are explicitly specified in the design stan- or width of lane line for use with dual turn lanes. Both of the dards for the lane line between the two lanes of dual turn lanes: figures in Part 3 (Figures 3B-11 and 3B-22) that show dual MI, TN--4 in. NC--4 or 6 in. Lane line between two Lane line extension FL--6 in. lanes of dual turn lanes into intersection CO, NV, TUC--8 in. Length of Lane Line Between the Two Lanes of Dual Turn Lanes (7 agencies) The following lengths are explicitly specified in the design standards for the lane line between the two lanes of dual turn lanes: Lane line between Solid line between dual turn lanes and through lanes on a CA--at least 100 ft adjacent through lane signalized approach MD, MI, NV, TN, LAN, TUC--entire length of full-width FIGURE 4 Characteristics of dual turn lanes. turn lanes.