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 45
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.
OCR for page 46
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
OCR for page 47
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
OCR for page 48
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
OCR for page 49
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
