Cover Image

Not for Sale



View/Hide Left Panel
Click for next page ( 32


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 31
31 LAN) show that passing may be permitted in the single-lane The design standards for three other agencies show the direction. The design standards for Massachusetts also show broken lane line ending at a distance 0.75D upstream from that passing can be permitted in the climbing lane direction the upstream end of the transition taper, but with a different if sight distance allows, thus creating a third available lane means of determining the distance D. The means of deter- when there is a sufficient gap in opposing traffic. mining the distance D for these three agencies are as follows: The design standards for three agencies (AZ, MT, and FL--the values of D are 325 ft for 30 mph, 475 ft for WV) require that passing be prohibited in the single-lane 40 mph, 550 ft for 45 mph, 625 ft for 50 mph, and 700 ft direction. The design standards for Arizona also state that for 55 mph when uphill passing lanes are provided, the centerline for NC, OR--the values of D, which range from 175 ft for downhill traffic "shall be solid from 500 ft in advance of the 20 mph to 850 ft for 65 mph, are shown in a table. initial taper to 200 ft past the end of the terminal taper." The design standards for 12 agencies show the broken The design standards for California require that passing lane line ending at a specific distance upstream from the up- be prohibited in the single-lane direction if the ADT exceeds stream end of the transition taper. The distances for these 12 3,000. When the ADT is 3,000 or less, passing can be per- agencies are as follows: mitted in the single-lane direction provided that one or more YIELD TO UPHILL TRAFFIC signs are installed. CLT, LAN--0 ft NY--100 ft ID--200 ft LANE REDUCTIONS IA--190 ft for 25 mph, 300 ft for 35 mph, 415 ft for 45 mph, 565 ft for 55 mph 2003 MUTCD Provisions MN--200 ft GA--200 ft for 35 mph, 275 ft for 45 mph, 350 ft for Figure 3B-12 shows examples of the pavement markings that 55 mph are used where a lane is ending. Figure 3B-12 shows the bro- TUC--245 ft for 30 mph, 300 ft for 35 mph, 350 ft for ken lane line ending 0.75D upstream from the downstream 40 mph, 415 ft for 45 mph, 475 ft for 50 mph end of the full-width section, where D is the distance (based IN--375 ft on Section 2C.05) that a Lane Ends (W4-2) sign is placed AR--525 ft upstream from the downstream end of the full-width section. VT--550 ft This is consistent with Paragraph 5 of Section 3B.09, which MA--565 ft (shown as 170 m). says that, "Lane line markings should be discontinued one- quarter of the distance between the Lane Ends sign (see Sec- The design standards for Michigan show the broken lane tion 2C.33) and the point where the transition taper begins." line ending at a specified distance upstream from the upstream Lane-reduction arrows are not shown in Figure 3B-12 (see end of the transition taper. The distance in feet is calculated Appendix A for figures). using the formula 15(S - 10) + 25, where S is the higher of the posted or 85th percentile speed. Paragraph 19 of Section 3B.19 contains the following option: "In situations where a lane reduction transition The design standards for Maryland show the broken lane occurs, the lane reduction arrow markings shown in Figure line ending at a specified distance upstream from the upstream 3B-21 may be used." end of the transition taper based on speed (1,275 ft for 65 mph, 1,165 ft for 60 mph, 1,050 ft for 55 mph, 940 ft for 50 mph, and 825 ft for 45 mph). A 10-in.-wide dotted line (3-ft seg- Downstream End of Broken Lane Line ments with 9-ft gaps) is provided from the downstream end of (31 agencies) the broken lane line to the upstream end of the transition taper. The design standards for 11 agencies (AZ, CA, CO, DE, KY, The design standards for Mississippi show the broken LA, NV, ND, TN, UT, and PR) show the broken lane line lane line ending at an unspecified distance upstream from the ending at a distance 0.75D upstream from the upstream end upstream end of the transition taper. A 6-in.-wide dotted line of the transition taper. The design standards for Wyoming (2-ft segments with 12-ft gaps) is provided from the down- show the broken lane line ending 0.5D upstream from the stream end of the broken lane line to the upstream end of the upstream end of the transition taper. The design standards for transition taper. Pennsylvania show the broken lane line ending at a distance D upstream from the upstream end of the transition taper. For each of these 13 agencies, the distance D is the advance dis- Dotted Lane Line in Transition Area (1 agency) tance (based on Condition A in Table 2C-4 of the MUTCD) in feet that a Lane Ends warning sign is placed upstream from The design standards for North Carolina show a 4- to 6-in.- the upstream end of the transition taper. wide dotted line (2-ft segments with 13-ft gaps) from the end