Chapter 22
Hazard Markers and
Sight Boards
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Traffic Engineering Manual Vol 2, Chapter 22 - Edition 2, December 2001
AMENDMENT RECORD
Ed/Rev No
Page(s)
Issue Date
Amendment Description
Ed 1
All
July 1986
Original Manual
Ed 2
All
December 2001 New Edition
Ed 2 Rev 1
17
November 2010
Minor amendments relating to
AS 1742.2
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Revision 1, November 2010
Contents
22.1 GENERAL ..................................................................................... 22-5
22.2 CHEVRON HAZARD MARKERS ................................................... 22-7
22.2.1 One-way Hazard Marker .................................................... 22-7
22.2.2 Two-way Hazard Marker ..................................................... 22-8
22.2.3 Installation of Hazard Markers ........................................... 22-9
22.3 WIDTH MARKERS ...................................................................... 22-11
22.4 OBSTRUCTION MARKERS ........................................................ 22-13
22.5 T-JUNCTION SIGHT BOARDS .................................................... 22-15
22.6 CHEVRON ALIGNMENT MARKERS ........................................... 22-17
22.6.1 General ............................................................................ 22-17
22.6.2 Guide for the Use of Chevron Alignment Markers ............ 22-17
22.6.3 Location of Chevron Alignment Markers .......................... 22-17
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Hazard markers comprise of signboards with either :
■ alternate black and white chevrons where an indication of both the presence
of an obstruction and directional information is required, ie. chevron markers,
■ alternate black and white diagonal stripes erected in pairs to indicate points
where the formation width narrows, generally at structures, and traffic is
required to pass between, ie. width markers, or
Hazard Markers and
Sight Boards
22.1
General
■ alternate black and white vertical stripes to indicate the presence of an
obstruction within or above the road.
An exception to the above is the Chevron alignment sign, Section 22.6, which
has a yellow background and is used for the delineation of substandard curves.
Hazard markers should not be used at any obstruction with which there is low
probability of a collision, or which is readily visible itself, or is more appropriately
delineated by other signs or devices. Overuse, or inappropriate use, of hazard
markers, with or without other delineating devices, can create confusing
delineation arrays and reduce their effectiveness at the more critical locations.
The total effect of such devices at any location should be checked by on-site
inspection, preferably at night, to ensure that traffic paths are clearly delineated.
Special hazard marker shapes should be used only where a standard shape will
not fit a particular situation.
Hazard markers in vulnerable locations should be erected on easily replaceable
frangible posts, see Section 22.2.3 and 6.4.1.
Size should be chosen so that the marker can be placed in the median, with
recommended horizontal clearances without being bent. The bending of markers
reduces the retroreflective performance for approaching drivers.
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22.2.1
Hazard Markers and
Sight Boards
One-way Hazard Marker
One-way hazard markers indicate to the approaching traffic the direction to be
taken if the marker appears in their driving path. They may point to the left or
right as appropriate and are used as follows :
■ To delineate an abrupt narrowing of pavement, for example, at a lane drop as
shown in Figure 12.11,
■ At exposed ends of raised medians where traffic is required to pass to one
side. They are generally located 5 to 10 m (urban) or 10 to 20 m (rural) from
the end of the median,
22.2
Chevron
Hazard
Markers
■ On the central island of a roundabout to face entering traffic, see Figure
10.13,
■ To delineate the curved approach just prior to entering an intersection,
including on a splitter island. Refer to Figure 12.7 and Figure 2.16 in AS 1742.2
for examples of use,
■ To form an extra-wide two-way hazard marker for T-Junction Sight Boards,
by placing two one-way markers end to end, as shown in Figure 22.3, Types
3, 4 and 5,
■ In any other situation where an exposed obstruction requires definition, and
where all traffic must pass to one side.
This sign should not be used to provide extra delineation on substandard curves,
(see Section 22.6 for use of chevron alignment sign in such cases), or in lieu of
width markers to delineate both sides of the carriageway, as specified in Section
22.3.
The following types of one-way hazard markers are used :
D4-1-1
(A - 1600 X 400 MM)
(B - 3200 X 800 MM)
D4-1-2
(A - 450 X 450 MM)
(B - 600 X 600 MM)
D4-1-3
(1800 X 300 MM)
The D4-1-1 chevron hazard marker shall generally be used at all median islands
and other central carriageway obstructions which are at least 2.2 m wide, except
where the use of a D4-1-3 would be appropriate, as described below.
The D4-1-3 may be used as an alternative to the D4-1-1 sign where approach
speeds are 70 km/h or less, or where the installation of D4-1-1 will restrict sight
lines, eg. on intersection approaches or at roundabouts. A median width of at
least 2.4 m will be required for the installation of this marker. It may also be
used to form an extra-wide two-way hazard marker for a T-junction sight board
by placing two one-way markers end to end, as shown in Figure 22.3, Type 3.
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The D4-1-2 chevron hazard marker is used at median islands and other central
carriageway obstructions which are less than 2.2 m wide where a smaller chevron
hazard marker is required. Similarly they are used to delineate a splitter island
on a curved approach to an intersection where the larger sign, D4-1-1 or D4-1-3
is inappropriate.
FIGURE 22.1: USE OF ONE-WAY HAZARD MARKERS AT EXPOSED
MEDIAN ENDS WIDER THAN 2.6 METRES
22.2.2
Two-way Hazard Marker
The two-way hazard markers are used where it is necessary to delineate an
exposed obstruction or a traffic island nose at which traffic may pass to either
side.
The following types of two-way hazard markers are used :
D4-2-1
(1800 X 300 MM)
D4-V103 (1800 X 600 MM)
D4-V108 (1080 X 500 MM)
D4-V105 (A - 450 X 300 MM)
(B - 600 X 400 MM)
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The D4-2-1 and D4-V103 markers are used at exposed ends of raised medians,
median islands, separators, or other central carriageway obstructions at least
2.4 m wide. The D4-V103 is used where a larger than standard hazard marker
is required for enhanced conspicuity. The D4-V103 may also be used in
conjunction with the D4-V102 chevron marker to form an extra-wide two-way
hazard marker for a T-junction sight board as shown in Figure 22.3, Type 5.
The D4-V108 marker is used where the median width is between 1600 and
2400 mm.
Where the island or separator is narrower than 1600 mm, the central obstruction
arrow board D4-V105 is used.
It should be noted that VicRoads does not subscribe to the use of the D4-2-2
two-way hazard marker (ie. a one way chevron marker orientated so that the
chevron points upwards) as shown in Section 3.6.7.2 (b) of AS 1742.2 because
it does not provide clear directional indication for drivers.
22.2.3
Installation of Hazard Markers
Hazard markers are normally erected on 32 mm pipe posts, each 1625 mm
long, and 500 to 700 mm mounting height above pavement level, measured to
the underside of sign. Adjustment of the height or location of such markers
may be required where :
■ the approach conditions will require the markers to be raised or located to
give sufficient advance sight distance to the intersection, eg. at a crest,
■ the hazard markers located in the vicinity of intersections obscure sight
distance to opposing or intersecting traffic streams or pedestrian movements.
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Hazard Markers and
Sight Boards
D4-3 (L)
D4-3 (R)
(A - 450 X 900 MM)
(B - 600 X 1200 MM)
22.3
Width
Markers
Width markers are used as follows :
■ At Railway Level Crossings as part of the Railway Crossing Width Marker
Assembly, or in conjunction with it, as described in AS 1742.7 and illustrated
in Figure 11.
■ At Bridges in accordance with the following guides:
❑ Two-way Unkerbed Approaches (Typically Rural)
~ Where the clearance to bridge kerb or non-frangible obstruction from edge
of running lane is less than the shoulder widths given in Table 3.6.3 in the
VicRoads Road Design Guidelines.
These are typically 2.5 m, for an approach pavement (excluding shoulders)
7.0 m or more wide and 2.0 m, for an approach pavement (excluding shoulders)
less than 7.0 m wide.
❑ Two-way Kerbed Approaches (Typically Urban)
~ Where the width between kerbs on the approach is greater than that on
the bridge, or
~ Where there are non-frangible vertical obstructions less than 600 mm
clear behind the bridge kerb.
❑ Two-way Unsealed Approaches
~ Any bridge less than 2 m wider than the approach pavement or running
portion of the formation.
❑ One-way Approaches (typically on freeways)
~ Any bridge where full approach shoulder width is not carried across the
bridge.
For the above cases, markers are always placed on both sides of the road,
including sites where the guide for a marker is met on one side only. The markers
are located in front of, and as near as practicable to, the bridge end post with
inner edges approximately 300 mm clear of the line of the kerb face, or if
unkerbed, flush with the inner edge of the end post, see Figure 22.2.
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FIGURE 22.2: LOCATION OF WIDTH MARKERS ON BRIDGE
APPROACHES
The size of markers to be used is as follows:
A Size - Rural areas where traffic volume is less than 300 vpd AADT
B Size - All other cases.
Bridge width markers may be omitted on roads carrying less than 50 vpd AADT.
■ At Underpass Piers, Etc.
Width markers are used at underpass piers or similar carriageway constrictions
when the width between obstructions is less than the approach formation width
(which includes shoulder and verge). The markers should be placed on or just
in front of the obstructions with inner edge flush with inner edge of obstruction,
see Figure 13.8.
■ At Other Vertical Obstructions
Width markers may be used singly at other obstructions located either within
the carriageway, or so close to it as to constitute a hazard, eg. utility poles,
central bridge piers. The left-hand marker is used where traffic passes to the
right of the obstruction, and vice versa. Special markers may be designed
where the size or shape of the standard marker is inappropriate. For treatment
of obstructions in the centre of the carriageway, eg. bridge piers, see
Section 22.2.
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Hazard Markers and
Sight Boards
D4-5
(1800 X 450 MM)
22.4
Obstruction
Markers
The D4-5 obstruction markers are used to delineate obstructions within or above
the road.
Typical uses of these markers are :
■ To highlight road closures, either mid-block or at the end of a road
(eg. cul-de-sac, service road), and
■ To delineate vertical clearance above the road where height restrictions exist,
ie. overhead structures that require the display of a sign R6-11, LOW
CLEARANCE x.x m, see Section 8.8.7, and Figure 13.8.
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T
-junction sight boards are placed opposite the stem of a T-junction as
illustrated in Figures 10.8 and 10.9 as a target, and for guidance of traffic
approaching along the terminating road. They are generally used in rural areas,
but may also be used in urban areas where extra delineation of the end of the
terminating road is desirable, eg. at poorly lit intersections.
The assemblies comprise one or more hazard markers displayed, as illustrated
in Figure 22.3, Types 1 to 5, together with intersection direction signs provided
in accordance with Section 10.1.2 (also shown on Figure 22.3, as illustrations
of typical assemblies only). A guide to the use in rural areas of the various
types illustrated is given in Table 22.1.
Hazard Markers and
Sight Boards
22.5
T-Junction
Sight
Boards
The assembly should be located so that as far as practicable it is directly in
front of the driver and visible over the last 100 to 300 m (depending on approach
speed) of the approach to the intersection. Where there is a curve in the
terminating road just before the intersection, the sight board may need to be
offset to improve its visibility.
The normal mounting height is 1 m to underside of the hazard markers, but the
whole assembly may need to be raised if there is a crest in the terminating road
just before the intersection.
SIDE (TERMINATING) ROAD APPROACH
CONDITIONS
T-JUNCTION
SIGHT BOARD
TYPE
(FIGURE 22.3)
(1)
TRAFFIC
VOLUME
(AADT)
APPROACH
SPEED
(km/h)
APPROACH
ALIGNMENT
Type 1
< 100 vpd
< 90
Straight
Type 2
< 100 vpd
> 90
Straight
< 100 vpd
< 90
Curve or crest
> 100 vpd
< 90
Straight
100 - 600 vpd
> 90
Straight
100 - 600 vpd
> 90
Curve or crest
> 600 vpd
> 90
All cases
Type 3
Type 4
Type 5
TABLE 22.1: GUIDE FOR THE SELECTION OF T-JUNCTION SIGHT
BOARDS IN RURAL AREAS
Notes:
1. Refers only to display of hazard markers. Direction signs in Figure 22.3 are added as
illustrations of typical assemblies only.
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FIGURE 22.3: T-JUNCTION SIGHT BOARDS
(GUIDES FOR USE OF EACH TYPE GIVEN IN TABLE 22.1)
Notes:
1. Type No. refers to hazard marker assembly only.
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2. Intersection direction signs or free standing route marker with arrow plate should be
provided in accordance with Section 10.1.2.
Traffic Engineering Manual Vol 2, Chapter 22 - Edition 2, December 2001
22.6.1
Hazard Markers and
Sight Boards
General
D4-6
(A - 600 x 750 mm)
(B - 750 x 900 mm)
(C - 900 x 1125 mm)
22.6
Chevron
Alignment
Markers
These markers are used to enhance the delineation of substandard or other
curves in accordance with requirements given in AS 1742.2, Clause 4.4.7.11
and as outlined below.
Chevron alignment markers should not be used for any other purpose, including
those situations for which Chevron hazard markers are appropriate, see Section
22.2. Misuse will undermine the effectiveness of this important delineation device.
A minimum of three markers is required at any one curve in any one direction.
A minimum of two markers should be visible from a point on each approach
to a curve from a distance equivalent of 3 seconds of travel time in advance
of the start of curve. However, markers are not normally required on single
curves whose deflection angle is less than about 45 degrees, unless there are
special curve visibility or other problems.
22.6.2
Guide for the Use of Chevron Alignment Markers
Guides for the size of sign and use of these markers at substandard curves
are given in Figure 4.6 of AS 1742.2.
In addition to the above guides, chevron alignment markers may be used :
■
to enhance the delineation of any curve which is hidden from view by the
vertical alignment, etc., and hence may not be appreciated by a driver,
■
as a crash countermeasure where there is a history of curve related crashes.
In either case, the markers should only be used where curve or turn warning
signs (Section 9.2.2), and post or other delineation (Section 23), are already
existing but not adequate by themselves.
22.6.3
Location of Chevron Alignment Markers
Chevron Alignment Markers are located as shown in Figures 4.7 and 4.8 and
spaced in accordance with Table 4.3 of AS 1742.2.
In general, the markers are erected at a height of approximately 1.2 m (but may
be increased up to 1.5 m to improve visibility where there is a preceding crest
or other visual impairment) and placed as close to the roadway on the outside
of the curve as practicable, within the lateral clearance limits given in Figure 5.1.
Mounting shall be such that their tops form a smooth line around the curve.
The principles in Appendix D of AS 1742.2 regarding installation and location
of signs should be observed. The markers should be angled towards oncoming
traffic such that they are at right angles to an approaching vehicle at the limit of
visibility of the marker (subject to the requirements of Section 5.5). On larger
radius curves, they may be mounted back to back, as shown in Figure 22.4.
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FIGURE 22.4: BACK TO BACK MOUNTING OF CHEVRON ALIGNMENT
MARKERS
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