General Sign Treatments for Rural Intersections & Junctions
Operational Instruction
2.27
Transport Services Division
TRAFFIC MANAGEMENT
Operational Instructions General Sign Treatments for Rural Intersections & Junctions - 2.27
AMENDMENT RECORD
Version E1/R2 Ver 2
Page(s) 3,4 &9 All
Date 7/01 21/05/08
Amendment Description Draft (prep by B Zhang) Format Changes
Init BZ DW
This document has been prepared by Traffic and Access Standards Section. It has been approved and authorised for use by Department for Transport, Energy and Infrastructure and its authorised agents by:
Manager, Traffic and Access Standards Section 2 / 7 / 2001
Extracts may be reproduced providing the subject is kept in context and the source is acknowledged. Every effort has been made to supply complete and accurate information. This document is subject to continual revision and may change. For information regarding the interpretation of this document please contact: Transport Services Division Telephone: (08) 8343 2289 Facsimile: (08) 8343 2630 For additional copies or to confirm the current status of this document please contact: Traffic and Access Standards Section Department for Transport, Energy and Infrastructure Telephone: (08) 8343 2849 Facsimile: (08) 8343 2630 email: david.widdrington@saugov.sa.gov.au
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General Sign Treatments for Rural Intersections & Junctions - 2.27 CONTENTS 1. Scope................................................................................................................................. 4 2. Background ...................................................................................................................... 4 3. Regulatory Signs .............................................................................................................. 4 3.1. Stop Signs .................................................................................................................. 4 3.2. Give Way Signs.......................................................................................................... 5 4. Advanced Warning Signs for Intersections and Junctions.......................................... 5 4.1. Side Road Approaches .............................................................................................. 6 4.2. Main Road Approaches.............................................................................................. 7 5. Hazard Markers................................................................................................................. 7 5.1. Single Lane Approach ................................................................................................ 8 5.2. Multi-Lane Approach ................................................................................................. 9 5.3. Hazard Marker Height ............................................................................................. 10 5.4. Curves on the Approach to a T-Junction................................................................. 11 5.5. Divided Carriageway ............................................................................................... 12 5.6. Bidirectional Hazard Markers .................................................................................. 14 6. Pedestrian Actuated Traffic Lights ............................................................................... 16 7. Indented Parking Bays................................................................................................... 16
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General Sign Treatments for Rural Intersections & Junctions - 2.27
1.
Scope
This Operational Instruction outlines the principles and uses of regulatory signs, advanced warning signs and hazard markers at junctions and intersections, and should be used in conjunction with AS 1742.2. It discusses the use of advanced direction signs in relation to advanced warning signs but does not specify when advanced direction are necessary. Intersection treatments for divided roads is outlined in Operational Instruction 2.21.
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2. Background
There is a need to ensure road users are aware of approaching road characteristics. Where sight distance to junctions and intersections is limited devices such as advanced direction signs and warning signs can be used to inform road users. It is important to ensure that the correct messages are sent to road users and the amount of information received is kept to a minimum. The minimum amount of signs should be used to ensure that drivers have time to comprehend the messages and do not become confused. Also overuse of individual signs reduces their long-term credibility.
3.
Regulatory Signs
3.1 Stop Signs
Stop sign indicates to road users who has the right-of-way and should not be considered as a standard treatment at junctions or intersections. Stop signs shall be used only where warranted. Overuse of Stop signs reduces their effectiveness, and are often ignored by motorists and intentionally violated if used where they are not justified. At intersections where sight distance is limited to that specified in AS1742.2 Stop signs shall only be used if the sight distance cannot be improved by the removal of vegetation, buildings or other obstructions. At intersections with a high crash frequency, a detailed investigation shall be undertaken to determine the contributing factors to the crashes. Treatment, other than by the installation of a Stop sign, may be more beneficial to the reduction of crashes. Stop signs shall not be supplemented with any other sign.
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General Sign Treatments for Rural Intersections & Junctions - 2.27 3.2 Give Way Signs Give way signs (R1-2) and the associated pavement markings are not generally necessary on rural T-junctions. They may be used at T-junctions where it is not evidently clear to motorists which traffic route has the right of way, or where there is a perception to drivers that the incorrect route has right of way. Such scenarios may be encountered where a highway forms the stem of Tjunction and on leg of the top with an road of a lower classification. Motorists travelling on the highway on the side road approach may be under the impression that when turning of the stem of the junction, to continue on the highway, they have the right of over vehicles travelling on the arterial or local road.
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Rural arterial or local road
Highway
Highway
Figure 1 Where two roads cross over the minor road should display a Give Way sign provided sight distance is adequate. Where sight distance is limited a Stop sign may be installed.
4.
Advance warning signs for intersections and junctions
To maintain their effectiveness intersection and junction warning signs shall be limited to those with a greater than general hazard. Intersection and junction warning signs shall not be used where direction signs, other devices or geometric clues (day and night) give sufficient information to motorists about the existence of an intersection.
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General Sign Treatments for Rural Intersections & Junctions - 2.27 4.1 Side road approaches Advance warning signs shall be used on the minor road approach only when there is no advance direction sign and the stopping sight distance to the junction is less than the values given in table 1. An advance direction sign on the approach to intersections provides adequate warning to road users. W3-1 Where advance warning of an intersection is required the appropriate W3 series (advance warning of traffic control device) sign shall be used.
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Signing for advance warning of a traffic control device indicates to motorists the action that is required at the junction. This allows the motorist to be focused on the act of stopping for or giving way to vehicles on the main road.
W3-2
Previously intersection and junction series warning signs have been used to indicate the intersection type to motorists. By indicating the type of control at the approaching junction the emphasis is placed on complying to the regulatory device rather than on letting the driver consider the direction that they would like to travel when they reach the intersection.
T-junction warning signs (W2-3) shall only be used at junctions not controlled by give way or stop signs, if there is no advanced direction sign and if the stopping sight distance to the junction is less than the values given in table 1.
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General Sign Treatments for Rural Intersections & Junctions - 2.27 Approach Speed 31 - 40 41 - 50 51 - 60 61 - 70 71 - 80 81 - 90 91 - 100 100 - 110 111 - 120 Stopping sight distance, metres 35 45 65 85 115 140 170 210 250
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Note: This table has been adapted from Rural Road Design, Austroads, 1989 (Table 6.2). Values given for the speed ranges 70 km/h and below are based on a reaction time of 2.0 sec, and those above, of 2.5 sec. The Approach Speed is the representative speed (usually taken as the 85th percentile) of traffic approaching a site.
Table 1 Stopping sight distance on level sealed pavements 4.2 Main road approaches There is a tendency to over use junction warning signs on the main road. The main road traffic is not required to give way or take an action for minor road traffic. The responsibility for movements into the junction is held by the traffic exiting from the minor road. To maintain their effectiveness, intersection warning signs on the main road shall be limited to intersections where the stopping sight distance to the junction is less than the values given in table 1. Where advanced direction signs are installed on the approach to a side road, junction warning signs shall not be used. The cross road sign shall not be used on a side road approach to a controlled intersection. W2-4 W2-1
5.
Hazard Markers
Hazard markers are used to indicate the presence of a junction, to delineate traffic islands, to identify a hazard close to the carriageway or to indicate the presence of a low bridge or structure. Hazard markers shall be installed at the stem of a T-junction where the approach speeds from the stem of the T-junction are a minimum of 90km/h. Hazard markers are not necessary at T-junctions where there is a two way directional sign or two single direction signs (refer to figure 2). Hazard markers shall be centred on the approaching lane, not on the centre of the intersection.
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General Sign Treatments for Rural Intersections & Junctions - 2.27 Note: Hazard markers used by Transport SA have different dimensions to those specified by the Australian Standard. This Operational Instruction does not include the use of Chevron Alignment Markers CAMS (D4-6). The use of CAMS is detailed in OI 2.1.
Two direction signs or Two-way direction sign
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Figure 2 Direction signs alone indicate the options to road users
5.1
Single lane approach At junctions where the side road has a single lane approach D4-SA2-1 Hazard marker is normally adequate.
D4-SA2-1
Figure 3 Typical T-Junction
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General Sign Treatments for Rural Intersections & Junctions - 2.27
D4-SA2-1
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Figure 4 Placement of hazard marker at junction of less than 90 degrees 5.2 Multi-laned approach Where the side road is a non-channelled multi lane approach (designated left and right turn lanes) or a wide single lane approach two D4-SA1-1 may be used backto-back. In rare circumstances more than two D4-SA1-1 hazard markers may be used to give prominence to the junction where: • traffic volumes are high on the side road • sight restrictions exist due to a curve or crest preceding the junction
D4-SA1-1
D4-SA1-1
Figure 5 Unchannelised multi-laned approach Where the side road is a channelised multi laned road a D4-4 should be adequate.
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General Sign Treatments for Rural Intersections & Junctions - 2.27
D4-4
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Figure 6 Channelised multi laned approach 5.3 Hazard marker height Where the road level on the approach to the T-junction is generally flat or has a minor a slope, the hazard marker shall be installed so that the distance between the top of the marker and the projected line of the pavement where the side road vehicle approaches the junction is 1.5m. The height is selected to reflect a passenger vehicle headlights and be in a horizontal line with the drivers sight. Where the side road approaches the junction at a high angle an additional level of hazard markers may be necessary to alert motorists of the approaching junction as soon as possible. Hazard markers shall be placed 600mm behind the line of guide posts where adjacent lane use permits. Where guide posts are not present hazard markers shall be placed 600mm behind the edge of the road formation.
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General Sign Treatments for Rural Intersections & Junctions - 2.27
Line of guide posts or edge of formation
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Drivers line of sight 1.5m
Headlight focus 600mm
1.5m
Gentle slope
Figure 7 Hazard marker installation height 5.4 Curves on the approach to a T-Junction Unidirectional hazard markers shall be installed on curves which are closely followed by a T-junction. Speed advisory signs shall not be used under these circumstances. Advanced intersection warning shall only be used where the sight distance from the start of the curve to the intersection is less than the stopping sight distance given in table 1. Where there is no advanced direction sign and advanced warning is required due to limited sight distance at a controlled intersection the relevant W3-1 or W32 sign shall be used. Warning signs for junctions shall not be combined with curve warning signs for substandard curves. Where it is necessary to warn of a horizontal curve and an uncontrolled junction at or near the same location a W2-14 sign, T-junction beyond curve, shall be used. An advisory speed sign shall not be used in conjunction with this sign.
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General Sign Treatments for Rural Intersections & Junctions - 2.27
Figure 8
D4-SA2-1
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D4-1-2
5.5
Divided Carriageway Sight boards shall be installed at a T-junctions formed by a high speed rural road and a divided road, regardless of the median width. For further information regarding divided carriageway signage refer to Operational Instruction 2.21. Where a side road joins a divided carriageway but motorists must turn left because there is no break in the median a One way sign (R2-2) sign is adequate.
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General Sign Treatments for Rural Intersections & Junctions - 2.27
D4-4
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Figure 9 Divided carriageway use sight board
R2-2
Figure 10 Divided carriageway with unbroken median use One Way sign
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General Sign Treatments for Rural Intersections & Junctions - 2.27 5.6 Bidirectional Hazard Markers Where a through lane becomes a left turn lane at an intersection a bidirectional hazard marker (D4-2-2) may be used only of the sight distance of motorists entering the main road is restricted below the relevant values given in table 1.
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Figure 11
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General Sign Treatments for Rural Intersections & Junctions - 2.27 Where a left turn lane exists a bidirectional hazard marker is not necessary.
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Figure 12 Bidirectional hazard markers are not to used where they restrict motorists sight distance while exiting from a side road.
Figure 13
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General Sign Treatments for Rural Intersections & Junctions - 2.27
6.
Pedestrian Actuated Traffic Lights
D4-1-2 unidirectional hazard markers shall be displayed on traffic light poles for pedestrian actuated traffic lights where the light poles are placed on a kerb extension.
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D4-1-2
Figure 14
7.
Indented Parking Bays
Where consecutive parking bays have been formed by the use of kerb protrubences at side road junctions, a unidirectional hazard marker D4-1-2 shall be installed on the first kerb protrubences only.
Figure 15 Indented parking treatment
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