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45 CHAPTER SIX CONCLUSIONS AND FUTURE RESEARCH NEEDS Although Part 3 of the Manual on Uniform Traffic Control · Types and patterns of longitudinal lines, Devices contains provisions for pavement markings on streets · Use of black contrast markings on concrete surfaces, and highways across the United States, it does not require or · Centerline markings on two-lane roads approaching recommend uniformity for many of the aspects of pavement signals and STOP signs, marking layout that were studied in this synthesis. This flex- · No-passing zones on two-lane roads approaching inter- ibility and latitude given to the states and local governments sections and grade crossings, has resulted in a wide variety of policies and practices among · Railroadhighway grade crossings, the various agencies as documented in this report. Tables 1, · Transitions between divided and undivided highways, 2, and 3 show the range of values and the most common prac- · Dotted guidelines and lane line extensions through tices found in the design standards for the various agencies intersections, for pavement markings at intersections, pavement markings · Edge line extensions through medians and intersections, between intersections, and pavement markings at interchanges, · Yield lines and yield ahead symbols, respectively. · Markings on acceleration lanes downstream from the gore area, In some cases, such as the width of a line, road users · Markings on deceleration lanes upstream from the gore who travel from one state to another might be unaware area, of the difference. In other cases, road users might experi- · Exit ramps with through lane drops, ence confusion about pavement markings that are unfamil- · Exit ramps with through lane drop and option lane, iar to them. · Reversible lanes, · Curb markings, · Parking spaces, States and local government agencies most likely appre- · Accessible parking for persons with disabilities, ciate some degree of flexibility and latitude as they develop · Bypass lanes, and implement their various pavement marking policies and · Passing flare or auxiliary bypass lanes at the top of T practices. Variations in line widths and sizes of gaps between intersections, line segments in broken or dotted lines may be attributable to · Paved turnouts, the economics of construction and maintenance. States with · Bus turnouts, tight budgets might specify narrower lines and longer gaps to · Truck and bus turnouts at non-exempt railroad cross- save money, whereas states that have larger proportions of ings, older drivers might favor wider lines and shorter gaps. · Runaway truck ramps, · Speed measurement markings, It is hoped that this synthesis will be used by FHWA and · High-occupancy vehicle and other preferential lane the National Committee on Uniform Traffic Control Devices markings, in the development of the 2008 edition of Part 3 of the Man- · Approaches to narrow bridges, ual on Uniform Traffic Control Devices to develop new stan- · Bike lanes, dards, upgrade existing guidance to standards, and upgrade · Speed humps and speed tables, existing options to guidance. In addition, it is hoped that state · Roundabouts, and local governmental agencies will use the information in · Toll plazas, this synthesis to determine the most common policies and · Rest areas, practices in each area of interest as they develop or revise · Raised pavement markers, their pavement marking design standards. · Rumble strips, · Delineators, Because this synthesis was limited to a finite number of · Object markers, areas of interest, there remains a need to research and syn- · Cattle guards, thesize other aspects of pavement marking layouts. Among · Temporary traffic control, and the pavement markings not included in this synthesis were: · Markings that are presently in the experimental stage.
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46 TABLE 1 SUMMARY OF RANGES AND MOST COMMON PRACTICES IN CHAPTER TWO--PAVEMENT MARKINGS AT INTERSECTIONS Range Most Common Practice No. of Area of Interest Low End High End Practice Agencies Turn Lanes Type of lane line between a turn bay and the Broken lane line Solid lane line Solid lane line 42 of 47 adjacent through lane Width of lane line between a turn bay and the 4 in. 12 in. 8 in. 15 of 31 adjacent through lane Length of lane line between a turn bay and the Half the length of the Entire length of the Entire length of the 13 of 26 adjacent through lane full-width turn lane full-width turn lane full-width turn lane Type of lane line between a dropped lane and Broken lane line Solid lane line Solid lane line 10 of 14 the adjacent through lane Width of lane line between a dropped lane and 4 in. 8 in. 8 in. 3 of 5 the adjacent through lane Use versus non-use of turn arrows in turn bays Typically not used Required Required 38 of 47 Use versus non-use of only word markings in Not used Required Optional 12 of 30 turn bays Placement of turn arrow nearest to the stop 4 ft upstream 75 ft upstream 20 ft upstream 7 of 38 line in turn bays Placement of word or symbol marking nearest to the upstream end of the full-width turn 0 ft downstream 33 ft downstream 0 ft downstream 15 of 22 lane in turn bays Use versus non-use of turn arrows in dropped Required Required Required 14 of 14 lanes Use versus non-use of only word markings in Optional Required Required 10 of 14 dropped lanes Lane Lines for Dual Turn Lanes Type of lane line between the two lanes of Broken lane line Solid lane line Solid lane line 8 of 11 dual turn lanes Width of lane line between the two lanes of 4 in. 8 in. 8 in. 3 of 7 dual turn lanes Length of lane line between the two lanes of Entire length of the Entire length of the At least 100 ft 6 of 7 dual turn lanes full-width turn lanes full-width turn lanes Type of lane line between dual turn lanes and Combination solid Solid lane line Solid lane line 10 of 11 the adjacent through lane and dotted lane line Width of lane line between dual turn lanes and 4 in. 8 in. 8 in. 4 of 7 the adjacent through lane Entire length of the Length of lane line between dual turn lanes Entire length of the Entire length of the full-width turn lanes 6 of 7 and the adjacent through lane full-width turn lanes full-width turn lanes plus half of taper Lane Line Extensions into Intersection for Dual Turn Lanes Use versus non-use of dotted lines Optional Required Optional 13 of 23 0.5-ft segments with 3-ft segments with 2-ft segments with Pattern of dotted lines 13 of 26 2-ft gaps 9-ft gaps 4-ft gaps Width of dotted lines 4 in. 8 in. 4 in. 6 of 7 Use and Type of Dotted Lines in Turn Lane Tapers Use versus non-use of dotted lines Not used Required Not used 30 of 43 2-ft segments with 6-ft segments with 2-ft segments with Pattern of dotted lines 5 of 12 4-ft gaps 10-ft gaps 4-ft gaps
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47 TABLE 1 SUMMARY OF RANGES AND MOST COMMON PRACTICES IN CHAPTER TWO--PAVEMENT MARKINGS AT INTERSECTIONS (Continued ) Range Most Common Practice No. of Area of Interest Low End High End Practice Agencies Width of dotted lines 4 in. 8 in. 4 in. 3 of 6 Left-Turn Lanes Added Between Through Lanes of Two-Lane Highways Half of left-turn lane Full width of left- Full width of left- Amount of widening 17 of 21 width turn lane turn lane Distance from full shadowing to upstream end 0 ft Half of shifting taper 0 ft 13 of 17 of left-turn taper Length of left-turn taper 50 ft 180 ft No two alike 1 of 21 Solid Lane Lines Between Through Lanes on Signalized Approaches Use versus non-use of solid lane lines between Broken lane line Solid lane line Broken lane line 29 of 42 through lanes Length of solid lane line between through 27 ft 500 ft 50 ft 4 of 13 lanes Width of solid lane line between through lanes 4 in. 6 in. 4 in. 6 of 13 Crosswalks Standard or high- Standard crosswalks High-visibility Use of standard and high-visibility crosswalks visibility crosswalks 33 of 50 only crosswalks only may be used 6 ft (measured to 6 ft (measured to Minimum width of crosswalks outside edges of 20 ft inside edges of 17 of 44 transverse lines) transverse lines) Width of transverse crosswalk lines 6 in. 24 in. 12 in. 12 of 40 Longitudinal (or Longitudinal lines Longitudinal lines Design of high-visibility crosswalks diagonal) lines and 21 of 38 only only transverse lines Width of longitudinal and diagonal lines 12 in. 36 in. 24 in. 17 of 38 Spacing of longitudinal and diagonal lines 12 in. 60 in. 24 in. 14 of 37 Standard or high- Standard crosswalks High-visibility Use of standard and high-visibility crosswalks visibility crosswalks 33 of 50 only crosswalks only may be used Stop Lines Not used if Required on Required on Use versus non-use of stop lines crosswalks are signalized signalized 42 of 46 present approaches approaches Width of stop lines 12 in. 24 in. 24 in. 24 of 43 Placement of stop lines 4 ft At least 5 ft At least 4 ft 21 of 38 Right-Turn Channelizing Islands Width of lines that mark the edges of right- 4 in. 48 in. 8 in. 12 of 18 turn channelizing islands Width of lines within right-turn channelizing 6 in. 24 in. 12 in. 8 of 18 islands Number of feet Spacing of lines within right-turn channelizing Tie between 10 ft and 5 ft equals posted speed 4 of 16 islands 20 ft limit in mph
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48 TABLE 2 SUMMARY OF RANGES AND MOST COMMON PRACTICES IN CHAPTER THREE--PAVEMENT MARKINGS BETWEEN INTERSECTIONS Range Most Common Practice No. of Area of Interest Low End High End Practice Agencies Minimum Length of Passing Zones Minimum length of passing zones 200 ft 1,000 ft 400 ft 10 of 22 Minimum Length of No-Passing Zones Minimum length of no-passing zones 250 ft 550 ft 500 ft 12 of 14 Two-Way Left-Turn Lanes (2WLTLs) Use versus non-use of left-turn arrows Optional Required Required 33 of 37 Spacing between opposing left-turn arrows in 5 ft 33 ft 32 ft 13 of 36 a set of arrows Minimum spacing from one set of arrows to Tie between 100 ft 100 ft 1,300 ft 2 of 10 the next set of arrows and 200 ft Maximum spacing from one set of arrows to 200 ft 2,640 ft 300 ft 4 of 14 the next set of arrows Spacing from one set of arrows to the next set 200 ft 1,320 ft No two alike 1 of 12 of arrows Climbing or Passing Lanes Double broken Type of lane line Broken lane line Broken lane line 19 of 22 lane line Start (upstream end) of lane line (measured from upstream end of full-width climbing or 0 ft 250 ft downstream 0 ft 18 of 22 passing lane) 0.75D (where D is End (downstream end) of lane line (measured the advance from downstream end of full-width climbing 0 ft 650 ft upstream 7 of 18 placement distance or passing lane) for a Lane Ends sign) Use of lane-reduction arrows Not used Required Not used 14 of 18 Number of lane-reduction arrows At least 2 3 3 3 of 4 Passing permitted or prohibited in opposing Permitted Prohibited Permitted 17 of 21 (single-lane) direction Lane Reductions 0.75D (where D is Downstream end of broken lane line the advance (measured from upstream end transition 0 ft 565 ft upstream 11 of 31 placement distance taper) for a Lane Ends sign) Use of lane-reduction arrows Not used Required Not used 17 of 31 Number of lane-reduction arrows 2 5 3 7 of 14 Painted Medians, Paved Shoulders, and Approaches to Obstructions Use versus non-use of diagonal lines within Not used Used Used 27 of 39 painted medians Width of diagonal lines within painted 6 in. 24 in. 12 in. 12 of 34 medians Spacing of diagonal lines within painted 5 ft 100 ft 20 ft 5 of 33 medians Double yellow 12-in.-wide solid Double yellow Lane lines surrounding painted medians 37 of 39 centerlines lines centerlines Use versus non-use of diagonal lines on paved Not used Optional Optional 18 of 20 shoulders Width of diagonal lines on paved shoulders 6 in. 24 in. 12 in. 9 of 20 Spacing of diagonal lines on paved shoulders 5 ft 100 ft 20 ft 2 of 17 Width of diagonal lines or chevrons on 8 in. 18 in. 12 in. 6 of 8 approaches to obstructions Spacing of diagonal lines or chevrons on 5 ft 25 ft 5 ft 2 of 6 approaches to obstructions
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49 TABLE 3 SUMMARY OF RANGES AND MOST COMMON PRACTICES IN CHAPTER FOUR--PAVEMENT MARKINGS AT INTERCHANGES Range Most Common Practice No. of Area of Interest Low End High End Practice Agencies Entrance Ramp Gores Width of channelizing lines 4 in. 12 in. 8 in. 26 of 43 Upstream end of the channelizing line on the left-hand side of the entrance ramp 0 ft 50 ft 0 ft 25 of 42 (measured from the upstream end of the paved gore) Downstream end of the channelizing line on At point where ramp At upstream end of At downstream end the left-hand side of an entrance ramp with a and mainline lane are 11 of 26 paved gore of paved gore tapered acceleration lane 6 ft apart Use versus non-use of a channelizing line on Not used Required Required 26 of 42 the right-hand side of the mainline roadway Upstream end of the channelizing line on the right-hand side of the mainline roadway 0 ft 50 ft 0 ft 23 of 34 (measured from the upstream end of the paved gore) Use versus non-use of chevrons within the Not used Required Not used 36 of 44 paved gore Width of chevrons within the paved gore 8 in. 24 in. 12 in. 2 of 7 Spacing of chevrons within the paved gore 7 ft 100 ft 20 ft 2 of 7 Exit Ramp Gores Width of channelizing lines 6 in. 12 in. 8 in. 27 of 44 Use versus non-use of channelizing line on Required Required Required 44 of 44 right-hand side of mainline roadway At point where full At point where full At point where full Upstream end of channelizing lines for exit width of exit ramp width of exit ramp width of exit ramp 44 of 44 ramps with tapered deceleration lanes becomes available becomes available becomes available Downstream end of channelizing line on left- hand side of exit ramp (measured from the 0 ft 50 ft 0 ft 24 of 43 downstream end of the paved gore) Downstream end of channelizing line on right- hand side of mainline roadway (measured 0 ft 150 ft 0 ft 21 of 43 from the downstream end of the paved gore) Use versus non-use of chevrons or diagonal Not used Required Not used 18 of 44 lines within the paved gore Width of chevrons or diagonal lines within the 8 in. 24 in. 12 in. 11 of 25 paved gore Spacing of chevrons or diagonal lines within 7 ft 100 ft 20 ft 5 of 23 the paved gore Use versus non-use of dotted line in the Not used Required Required 20 of 41 departure area of a tapered deceleration lane Width of dotted line in the departure area of a 4 in. 8 in. 4 in. 15 of 28 tapered deceleration lane Type of dotted line in the departure area of a 2-ft segments with 5-ft segments with 2-ft segments with 12 of 28 tapered deceleration lane 4-ft gaps 20-ft gaps 4-ft gaps