This Guideline applies to all public roads in Western Australia.

Main Roads monitors all roads with a sign posted speed limit and approves changes to speed zones. For sealed roads subject to the Built-up area 50 km/h speed limit or the State 110 km/h speed limit, Main Roads will initiate a speed limit review or investigation on request from the agency responsible for the road or feedback from the public.

As recommended by Australian Standards, Main Roads does not speed zone or install advisory speed signs on unsealed roads. For these roads the built-up area 50 km/h speed limit, any other applied area speed limit, the State 110 km/h speed limit, or vehicle class default speed limit is applicable, subject to the driver driving at a speed appropriate to the road conditions.

All enquiries should be to the Road Services Officer (Speed Zoning) for the Metropolitan Region and the relevant Customer Services Manager in the Regional Office.  Contact details are provided on the website www.mainroads.wa.gov.au under Regions.

All enquiries should be to the relevant Project Manager for the roadwork in the Metropolitan or Regional Office.

Guidelines for temporary speed limit signs for roadwork are given on the website www.mainroads.wa.gov.au under Traffic/Roadworks.

All enquiries should be to the Road Services Officer (Events) in the Metropolitan Region and the relevant Customer Services Manager in the Regional Office. 

Guidelines for temporary speed limit signs for events are given on the website www.mainroads.wa.gov.au under Traffic/Events.

For Local Authority roads outside of the Perth Metropolitan Boundary, applications for advisory speed limit signing should be forwarded to the relevant Local Authority. For main roads, applications should be addressed to the Customer Services Manager in the Regional Office.

For all roads within the Perth Metropolitan Boundary, applications should be addressed to the Traffic Services Manager for the Metropolitan Region.

The road section shall be fully contained within a recognisable and dedicated tourist, recreation, conservation, shopping, commercial or industrial area / precinct / reserve subject to the following:

• Two-way single carriageway roads shall have a width of at least 5.0 metres,
  

• The start and end of the road section should have a threshold treatment,
  
  
• Minimum length of the speed zone shall be 400 metres,
  
  
• Mid-block speed-reducing devices shall be provided where the length exceeds 400 metres or where devices are necessary to create a speed environment consistent with the speed zone,
  
  
• Traffic volumes shall exceed 100 vpd on a typical weekday,
  
  
• The 85^th percentile speed for motor vehicles on existing roads, or expected on new roads, shall not be greater than 50 km/h or less than 30 km/h.

3.1.3.4. Speed Environment Road Characteristics

AS 1742.4-1999 Appendix B Section B3 shall be used except for sub-section B3.4 - Road Hazards, which is replaced with the following:

Speed limits should not be reduced for isolated road hazards, such as un-signalised intersections, railway level crossings and isolated curves. Features such as these should be treated with the appropriate warning and regulatory signs. However, where several hazards occur in close proximity to each other over a section of road 3 km or more, then a lower speed limit than that indicated by roadside development in Section 3.1.3.3 may be appropriate.

Traffic Signals, Roundabouts and Single Lane Bridges/Floodways are speed zoned as follows:

• Where the approach road is speed zoned at 90 km/h and above, the approach shall be a speed zone not greater than 80 km/h with a length not less than 300 metres before the feature,
  
  
• On divided carriageways, if offset speed zones are appropriate, the length of the speed zone should be reduced to 100 metres on the departure side of the feature.
  
  
• Due to the potential for high severity head-on and head-on evasion crashes at single lane bridges/floodways, associated traffic control devices should be provided in addition to normal speed zoning devices.

Road sections which have, or are proposed to have, a Winding Road sign (W1-5) and Next  ..km sign (W8-17-1) with a length of 3 km or more, shall be speed zoned.

3.1.3.5. Road Crash History

In addition to the requirements of AS 1742.4-1999 Section 2.3.2 (d) the following matters shall be considered:

• A high incidence of crashes along a section of road may indicate a road hazard (not apparent in consideration of Speed Environment Road Characteristics) and/or poor traffic conditions. If the road hazard and/or poor traffic conditions cannot be treated or treated in a reasonable period of time, or the reason for the crashes is not apparent, then a speed limit lower than the otherwise appropriate speed limit should be considered.

• Fully Built-up
  Description - Residential, business or industrial development extending along at least 90% of the road frontage on both sides of the road.  The development may include such facilities as commercial, industrial and playing fields.
  Speed Limit - The appropriate speed limit is 50 km/h but for urban arterial roads (District Distributor B and higher) 60 km/h is generally appropriate for road sections with 4 lane single carriageway, 70 km/h for 4 lane dual carriageway roads with some property access and 80 km/h for 4 lane dual carriageway with minimal or no direct property access. Urban arterial roads in rural townsites with retail and commercial strip development have above average pedestrian crossing activity and thus the appropriate speed limit is 50 km/h.
  
  
• Partially Built-up
  Description - Residential, business or industrial development ranging from 25% to 90% of the road frontage on both sides of the road. This is typical of the fringes to major urban centres and rural townsites.
  Speed limit - The appropriate speed limit is 80 km/h but 60 or 70 km/h may be appropriate if there is extensive vehicular or pedestrian activity on the road.
  
  
• Sparsely Built-up
  Description - Similar to partially built-up but the development extends along less than 25% of the road frontage or occurs on one side of the road only. This is typical of very small rural townsites.
  Speed Limit - The appropriate speed limit is 80 km/h but 90 or 100 km/h may also be appropriate if there is little vehicular or pedestrian activity on the road.
  
  
• Farmland
  Description - Not more than 30 residences per kilometre (total of the two sides) generally set well back from the road and no other development.
  Speed Limit - The appropriate speed limit is 100 or 110 km/h.
  
  
• Undeveloped
  Description - No development on either side of the road except for isolated houses set well back from the road.
  Speed Limit - The appropriate speed limit is 100 or 110 km/h.

Where development is markedly different on the two sides of a road and there is little movement across the road, a speed limit higher than that for the more developed side may be considered; or for divided roads, a different speed limit for each direction of travel.

Linear Speed Zone pavement markings, comprising white numerals, may be provided as follows:-

Within the Metropolitan Area

• For a speed limit decrease at the end of a significant length of road with 3 through lanes and a decrease from 100 km/h or higher.
• The location of the pavement marking is on a straight section of road.

Outside the Metropolitan Area

• For a speed limit decrease at the end of a significant length of road with a speed limit of 100 km/h or higher.
• The location of the pavement marking is on a straight section of road.

3.2.1.2. Additional Conditions for 30 km/h Area Speed Zones

The existing vehicle 85^th percentile speeds on all roads within the area shall not be greater than 40 km/h and not less than 20 km/h for all hours of a typical day.

3.2.1.3. Additional Conditions for 40 km/h Area Speed Zones

The existing vehicle 85^th percentile speeds on all roads within the area shall not be greater than 50 km/h and not less than 30 km/h for all hours of a typical day.

All roads or road sections without effective speed reducing devices shall not be more than 300m in length or, if longer, shall have an 85^th percentile speed of 50 km/h or less. Effective speed reducing devices may include Stop and Give Way signing, roundabouts, slow points and speed humps in conformance with the following guidelines in order of precedence as below:

• Main Roads Local Area Traffic Management.  See www.mainroads.wa.gov.au under Standards/Roads and Traffic Engineering/Traffic Management/Local Area Traffic Management,
  
  
• AS 1742.13-1991, Local Area Traffic Management,
  
  
• Austroads Guide to Traffic Engineering Practice Part 10, Local Area Traffic Management (2004).

The School Zone shall comply with the definition of a School Zone as given in the Road Traffic Code 2000.

The school associated with the School Zone shall be pre-primary, primary or secondary school (a pre-primary must operate 5 days a week and the same time as schools to be eligible).

The school shall have frontage and should have access to the road or carriageway to which the school zone applies.

School zone speed limits shall be as follows:

• 40 km/h school zone for adjoining speed zones of 50, 60 and 70 km/h, and
  
  
• 60 km/h school zone for adjoining speed zones of 80 and 90 km/h.

School days are determined by the Department of Education and Training. The times of operation shall be 7.30 AM to 9.00 AM and 2.30 PM to 4.00 PM, except in the Gascoyne, Pilbara and Kimberley Regions where the afternoon times of operation can be 2.00 PM to 3.30 PM if the school classes finish in this time period and all schools within the town or city agree. Times may vary between towns.

The roads within a School Zone shall not include:

• Freeways,
  
  
• Control of Access Highways,
  
  
• Primary Distributor roads with posted speed limits greater than 60 km/h or where children / pedestrian crossing facilities have been provided.
  
  
• Six-lane roads,
  
  
• Roads within an area speed zone equal or less than the proposed school zone,
  
  
• Two lane roads with the carriageway width greater than 10 metres. (Kerb extensions, medians or pedestrian refuge islands should be considered to reduce the width to less than 10 metres),
  
  
• Roads where direct access is restricted for children via physical barriers such as fencing, walls, embankments etc.
  

School Zones are not desirable but may be eligible for consideration on:

• Single carriageway road with a seal width less than 5.5 metres wide,
  
  
• Four-lane and two-lane undivided roads carrying over 15,000 vpd,
  
  
• Four-lane and two-lane divided roads carrying over 20,000 vpd,
  
  
• Four-lane roads with clearways.

School zone lengths should extend 50 metres beyond the frontages of the school and to achieve the following minimum lengths:

• 200 metres - where the school zone speed limit is 40 km/h,
  
  
• 300 metres - where the school zone speed limit is 60 km/h.

Where possible, the section of school zone on the main school frontage should be positioned such that the point at which most students enter and leave the school is approximately at the centre of that section of school zone.

The proposed school zone sections shall be extended to include childrens crossings, zebra crossings, pelican crossings or pedestrian refuges in the immediate proximity of the school.

Where two schools are nearby and they both independently satisfy the selection criteria, one continuous school zone serving both schools shall be applied if the separation distance between separate school zones is not greater than 300 metres.

3.4.1.1. 40 km/h School Zones

School Zone pavement markings, comprising a yellow rectangle with black numerals, shall be provided at entry points to a 40 km/h School Zone only if electronic speed limits are not provided, and: -

• The road has a speed limit greater than the Built Up Area 50 km/h default speed limit outside of the school zone times, or
• The road is Distributor road status and has an annual average daily traffic volume greater than 5,000 vehicles per day (applicable to Perth Metropolitan Region, City of Bunbury and City of Mandurah),
• The road is Distributor road status (applicable in all other rural locations),
• The location of the pavement marking is on a straight section of road and outside vehicle swept turning path at intersections.

3.4.1.2. 60 km/h School Zones

School Zone pavement markings, comprising a yellow rectangle with black numerals shall be provided at all entry points to a 60 km/h School Zone only if electronic speed limits are not provided and the location of the pavement marking is on a straight section of road and outside vehicle swept turning path at intersections.

Applications for general speed zones and/or changes to existing speed zones should be addressed to the Traffic Services Manager for the Metropolitan Region and the Customer Services Manager in the Regional Office.

The applicant should provide the following information:

• Applicants Name, Postal Address, E-mail Address and Telephone Number,
  
  
• Road Name and Section (linked to a physical landmark eg intersection),
  
  
• Outline of reasons for seeking a change to the existing speed limit or speed zone,
  
  
• Supporting reasons for a proposed speed limit.
  

Freeway exit and entry ramps shall be in accordance with AS 1742.8-1990 Figure 2.4(b).

Linear speed zones 50 km/h or higher shall be in accordance with AS 1742.41999 Section 2.3, with the following variations:

3.1.3.1 Seal Width

Two-way single carriageway roads less than 5.5 metres wide are not speed zoned.

Dual carriageway roads with one traffic lane in each direction shall have lane widths of at least 3.2 metres, exclusive of parking and bicycle lanes.

3.1.3.2 Road Function

Table 1 Hierarchy of speed limits shall be used in place of AS 1742.4-1999 Table 2.1 and 2.2 as follows:

Speed Limit	Application
50 km/h	This is the Built-Up Area Speed Limit applying to the majority of local roads. It may also be applied on highways through rural townsites.
60 km/h	Speed limit for most undivided district and primary distributor roads in built-up areas with direct access from abutting development.
70 km/h	Higher standard urban roads, generally divided roads having provision to safely store turning or crossing vehicles but with some or full direct access to the road from abutting development. May also be applied to undivided roads having low levels of direct access from abutting development.
80 km/h	Higher standard urban roads, generally divided roads having provision to safely store turning or crossing vehicles and minimal access from abutting development directly to the main carriageways. May also be applied to undivided roads having very low levels of direct access from abutting development. Maximum speed limit through traffic signals, roundabouts and single lane bridges. Major rural roads through small settlements with some abutting development.
90 km/h	Limited application on outer urban highways. Major rural roads through small settlements with some abutting development, but not warranting consideration as a built up area.
100 km/h	High standard urban highways and freeways.
110 km/h	Default speed limit for roads in non built-up areas.  Mainly used for speed zoning rural highways.

      Table 1 Hierarchy of Speed Limits

3.1.3.6. Minimum Length

AS 1742.4-1999 Table 2.3 Minimum Lengths of Speed Zones, with the following variations, shall be used:

Speed Limit	Minimum Length of Speed Zone
50 km/h	0.5 km
60 km/h	0.6 km
70 km/h	0.7 km
80 km/h	0.8 km
90 km/h	0.9 km
100 km/h	2 km
110 km/h	4 km

  Table 2 Minimum Lengths of Speed Zones

3.1.3.7. Location of Speed Zone Change

Except on divided carriageways where offset speed zones may be used, it is desirable that speed zone changes occur well away from major intersections to avoid distractions and to allow drivers to adapt to the lower speed limit before reaching the intersection. A typical distance of 300 metres is desirable where appropriate conditions exist. However, where the speed zone is lower on the other side of the intersection, the speed zone change should be installed as near as possible to the intersection to discourage continuation of the higher travel speeds through the intersection.

3.1.3.8. Buffer Zones

AS 1742.4-1999 Section 2.3.5 Buffer Zones shall not be used and is replaced with the following:

Where there is a reduction or increase in the speed limit of more than 30 km/h, a buffer zone of intermediate speed value shall be provided; except for the following situations:

• On exit ramps at interchanges with lengths insufficient to provide buffer zones of at least 300 metres,
  
  
• At approaches and departures to Shared Zones,
  
  
• On entry ramps at interchanges,
  
  
• On dual carriageway roads when the speed limit increases.

Dual carriageway roads with offset speed limits shall not have any median openings over the length of the offset speed zone within the buffer zone.

The length of the buffer zone should generally be 500 metres and not less than 300 metres.  Buffer zones can be longer than 500 metres to include substandard vertical or horizontal alignment or hazards.

The definitions for heavy vehicle, heavy vehicle speed zone and heavy vehicle speed zone sign are given in the Road Traffic Code 2000.

The normal speed zone restriction for heavy vehicles is 40 km/h but this may be varied depending upon the particular situation.

The conditions applicable to a heavy vehicle speed zone on a long steep descent are as follows:

• The requirements in AS 1742.2-1991 Section 3.9 for Steep Descent / Trucks Use Low Gear / Next km signing are to be met, and
  
  
• The grade of the descent shall be 6% or more, and extends over the corresponding minimum lengths shown in Table 3 as follows:

Applications shall only be made by the Local Government Authority with responsibility for the area in which the Area Speed Zone is proposed.

All applications should be addressed to the Traffic Services Manager for the Metropolitan Region and the Customer Services Manager in the Regional Office.

The application shall include:

• A scaled map showing the boundary of the proposed local area speed zone.
  
  
• A list of all roads in the proposed area, the traffic volumes and the 85^th percentile speed of traffic on these streets on an hourly basis.
  
  
• A list of all roads that will require installation of speed control calming devices, where appropriate.
  
  
• A list of all roads with substandard seal widths (less than 5.5 metres), and deteriorating surfaces.
  
  
• Drawings to show the location and details of all proposed and existing speed control devices, proposed and existing threshold treatments, proposed local area speed limit signs and the locations of conducted speed surveys.
  
  
• A brief description of a monitoring program. The monitoring program shall include at least local community attitudes and vehicle speeds.
  
  
• The date on which the area speed zone is planned to come into force (i.e. after completion of Main Roads approvals and Council completion of roadwork if any).
  
  
• A commitment by Council to measure speeds for the road sections with new speed control devices and to provide additional devices if the 85^th percentile speed exceeds the area speed limit by more than 10 km/h.
  
  
• A summary of consultation with the local community, police, emergency services and public transport authorities.

All applications should be addressed to the Traffic Services Manager for the Metropolitan Region and the Customer Services Manager in the Regional Office.

The applicant should provide the following information:

• Applicants Name, Postal Address, E-mail Address and Telephone Number,
  
  
• Road Name and Section (linked to a physical landmark eg intersection),
  
  
• Outline of reasons for seeking a heavy vehicle speed zone,
  
  
• Supporting reasons for a proposed speed limit.
  

Applications shall only be made by the Headmaster / Principal or Parents & Citizens Association of the school or initiated by the Road Services Officer (Speed Zoning).
All applications should be addressed to the Traffic Services Manager for the Metropolitan Region, or the Customer Services Manager in the Regional Office.

The applicant should provide the following information:

• Applicants Name, Postal Address, E-mail Address and Telephone Number,
  
  
• A sketch map showing the school location with road names, buildings, adjacent playing fields, parking and access points,
  
  
• For new schools, the anticipated starting date for the school opening.
  

Applications shall only be made by the Local Government Authority with responsibility for the area in which the Shared Zone is proposed.

All applications should be addressed to the Traffic Services Manager for the Metropolitan Region and the Customer Services Manager in the Regional Office.

The application shall include:

• A scaled map showing the proposed shared zone boundaries. The proposed shared zone shall have clear boundaries with other roads and features,
  
  
• The traffic volumes and the 85^th percentile speed of traffic on an hourly basis,
  
  
• Drawings to show the location and details of all existing and proposed speed control, traffic signing, traffic calming devices, threshold treatments and the locations of conducted speed surveys,
  
  
• A brief description of a monitoring program. The monitoring program shall include at least local community attitudes and vehicle speeds,
  
  
• A commitment by Council to measure speeds for the road sections with new speed control devices and to provide additional devices if the 85^th percentile speed exceeds the shared zone limit,
  
  
• A summary of consultation with the local community, Police Service, emergency services and public transport authorities,
  
  
• The proposed commencement date for the shared zone.

Unless otherwise indicated in the text of this Guideline:

Access Road means a road providing access to abutting properties.

AS means Australian Standard

Built Up Area Speed Limit means the 50 km/h speed limit applicable to a built up area as defined in the Road Traffic Code 2000, Part 1 - Preliminary.

Default State Speed Limit means the maximum speed limit applicable to a non-speed zoned road as defined in the Road Traffic Code 2000, Part 1 - Preliminary.

District Distributor A means a road that carries traffic between industrial, commercial and residential areas and generally connects to Primary Distributor roads.

District Distributor B means a road that is a similar function to a District Distributor A road but with reduced capacity due to flow restrictions caused by access to and roadside parking.

GVM means Gross Vehicle Mass

LATM means Local Area Traffic Management

Local Distributor means a road that carries local traffic within a land use cell and link District Distributors at the cell boundaries to access roads

Main Roads means Main Roads Western Australia.

Primary Distributor means a road that provides for major regional and inter-regional traffic movement and carries large volumes of generally fast moving traffic.  These roads can be strategic freight routes.

School Frontage Road means any road directly adjacent to any part of a school including playing fields

Threshold Treatment means a treatment that is placed at a perimeter or entry of a local area to inform motorists that they are entering a slow speed environment.

Vpd means vehicles per day.

85^th Percentile Speed means the speed at or below which 85% of all vehicles are observed to travel under free flowing conditions past a nominated point.  A guide to the determination of 85^th percentile speed is set out in AS 1742.4-1999 Appendix A.

3.2.1.1. Common conditions for 30 and 40 km/h Area Speed Zones

The traffic volume on all roads shall be less than 5,000 vpd.

All roads shall be fully contained within a shopping, commercial, industrial or similar area, recognisable and dedicated tourist, recreation, conservation precinct or reserve.

The area shall have a higher than normal pedestrian activity level, (eg Northbridge entertainment/restaurant area).

All roads within the area shall meet the definition of a built-up area as defined in the Road Traffic Code 2000.

Generally all roads within the area shall be local access or local distributor roads in a functional road hierarchy.

A reduction in operating speeds of not more than 30 km/h shall apply to all approaches to the speed zone.

The proposed area speed zones to be signed shall have a clearly defined boundary.  Primary distributor roads, district distributor roads and other major traffic routes are to retain a higher speed limit.

There is no arbitrary restriction on the maximum or minimum size of an area to which an area speed zone may be applied.  Generally, most area speed zones will naturally be restricted by the size of the shopping, commercial, industrial or similar area, recognisable and dedicated tourist, recreation, conservation precinct or reserve.  The adopted boundary of the zone and the associated speed limit signing should appear logical and clear to drivers.

The boundaries of the area, precinct or reserve should have a threshold treatment to clearly define the area.

Where a Local Government boundary passes through an area proposed for an area speed zone, close consultation and coordination will be necessary so that the zone is implemented within both municipalities simultaneously.  Failure by Local Governments to agree on the proposed area speed limit shall preclude the implementation of the proposed local area speed zone.

The proposed local area speed zone shall have a clearly defined boundary.

There is no arbitrary restriction on the maximum or minimum size of an area to which an area speed zone may be applied. Generally, most area speed zones will naturally be restricted by the boundaries, but the size of these areas should desirably be in the range of 8 to 12 square kilometres.

Acceptable features for the boundary are primary distributor roads, district distributor roads, local distributor roads, other major traffic routes that are to retain a higher speed limit, townsite development boundaries and physical boundaries such as rivers, lakes, railway lines and protected bushland.

Primary distributor roads, district distributor roads and other major traffic routes are to retain a higher speed limit.

Generally all roads within the area shall be local access or local distributor roads in a functional road hierarchy.

The adopted boundary of the zone and the associated speed limit signing should appear logical and clear to drivers.

The quantity of existing gravel roads within the proposed area speed zone must not exceed 15% of the total number. The quantity of existing substandard seal width roads within the proposed area speed zone must not exceed 15% of the total number. The combined total of gravel and substandard seal roads must not exceed 20%.

The boundaries of the area, precinct or reserve should have a threshold treatment to clearly define the area.

Where a Local Government boundary passes through an area proposed for an area speed zone, close consultation and coordination will be necessary so that the zone is implemented within both municipalities simultaneously. Failure by Local Governments to agree on the need for lowering the speed limit shall preclude the implementation of the proposed local area speed zone.

The Shared Zone shall meet the definition of a Shared Zone as given in the Road Traffic Code 2000.

The Shared Zone may consist of a network of roads or a single road.

The speed limit is 10 km/h and other limits are not permitted.

The Shared Zone should be located within a central business district, a tourist area or a heritage area, and

All roads within the area shall meet the definition of a built-up area and have street lighting to a suitable standard.

The roads shall have less than 300 vpd after the shared zone is installed.

Pedestrian movements shall predominate over vehicular movements.

The driving environment for motorised vehicles shall be such that vehicle-operating speeds are generally no more than 10km/h.

The Shared Zone may include laneways.

There shall be minimal turning and intersecting motorised vehicular traffic. 

The roads shall have significant physical interruption to vehicular traffic by the use of bollards, parallel parking bays, plants and landscaped areas. 

There shall be minimal need for reversing of motorised traffic in entering and departing parking bays. Angle and 90^o kerbside parking is not desirable.

Raised kerbs shall be removed to provide visual cues to drivers that pedestrians have right of way.

The shared zone shall be an integral part of an agreed traffic management plan for the area that was developed with community consultation.

Entrance and exit widths shall be narrowed so that there is a physical entry/exit to the zone.

Each road shall have a trafficable width of at least 2.5 metres for one-way traffic and 4.5 metres for two-way traffic.

Service and Emergency vehicles shall be able to use all roads.

Speed reduction devices should be installed at a spacing of approximately 40 metres and these should be staggered on opposite sides of the carriageway to create a weaving alignment through the shared zone. Devices should include planting areas to contain the area visually.  Bollards with reflectors may be used to delineate the shape of the roadway on the approach side of landscaping.

The surface texture of the shared zone shall be different from the surrounding road network.

Parking spaces and loading zones, where provided, shall be located adjacent to the trafficable path and clearly signed and marked.

Advisory speed signing shall be limited to horizontal and vertical curves (including LATM devices) on sealed highways, main roads and other speed zoned roads that have a design speed less than the speed limit. These are to be assessed for signing with curve warning and advisory speed signs, in accordance with AS 1742.2-1999, Clause 3.4 unless otherwise directed in this guideline.

Where there is a series of more than two closely spaced horizontal curves, some or all of which are substandard, the symbolic Winding Road sign (W1-5) shall be used at the beginning of the series of curves. The winding road sign used shall indicate the direction of the first substandard curve and the advisory speed sign shall indicate the advisory speed of the slowest curve.  However, if the series of curves extends over a distance of one kilometre or more and the slowest curve is more than 10 km/h slower than the others, the slowest curve is to be signed separately.

If the crash level on a section of speed zoned road with advisory speed signing becomes greater than the network average for that type of road, then that road section may be speed zoned at a lower value.