MRWA Supplement to Austroads Guide to Road Design - Part 6B - Roadside Environment

This Supplement has been developed to be read in conjunction with the Austroads Guide to Road Design (GRD) Part 6B: Roadside Environment (2015), a copy of which can be purchased via the Austroads website.

In Western Australia, Main Roads' policies, guidelines and standards take precedence over Austroads Guides and Standards Australia Standards. National Guides and Standards take precedence over International Guides and Standards, unless specifically stated otherwise.This Supplement has the same structure as the equivalent Austroads Guide and only additional requirements, clarifications, or practices different from Austroads appear. Where appropriate, this Supplement may also contain additional sections and figures not covered by Austroads, but the numbering sequence found in the Austroads Guide remains. Figures and Tables in this Supplement replace those with the same figure or table number in the equivalent Austroads Guide.

2. Environmental Aspects

2.2 Fauna Management

The concept of fauna underpasses is not new and has been receiving increasing attention in recent years. Knowledge regarding the installation and use of fauna underpasses is continually increasing, based on experiences in Australia and overseas. Staff in Main Roads’ Environment Branch maintain a list of projects that have incorporated fauna underpasses and they can be contacted for more information on the subject.

2.2.2 Design considerations – fauna underpasses

Grills shall be designed according to the advice given by the Department of Biodiversity, Conservation and Attractions for the selected species to use the underpass and those species that the grill is to protect the underpass from. For larger underpasses the installation of vertical bars at a set width might be required in the middle of the underpass to keep out bikes and other off road vehicles. Note that the use of grills at the entrances to underpasses will need to be balanced against the risk of debris entanglement that may substantially disrupt drainage flow through the culvert.

For more detailed information relating to Western Australia practice in relation to Fauna Underpasses refer to the Design of Fauna Underpasses guideline.

2.2.3 Fence aperture size

Refer to Standard Drawing 200331-110 and the Guide to the Design of Fencing and Walls.

2.2.4 Stock Crossing

In rural Western Australia it may be necessary to accommodate the periodic movement of stock across a road or highway. For detailed information relating to local practice refer to the Guidelines for Stock Crossings.

2.3 Noise Control

Noise Level Objectives are specified upper limits of traffic noise which apply outside residential buildings and other noise sensitive land uses (as defined in the Western Australian Planning Commission State Planning Policy 5.4).. They are listed in Table 2A and Table 2B. Due to the impracticality of controlling noise at the upper floors of multi-storey buildings, noise assessment is restricted to the ground floor levels.

Where possible the noise level objective targets in Table 2B are to be achieved, with a maximum height of noise barrier of 5.0 m. Where the noise level objective targets in Table 2B cannot be achieved, the noise level objective limits in Table 2A must be achieved.

Traffic noise assessments shall complement the requirements of the State Planning Authority as per the Road Traffic Noise Assessments. Information pertaining to Main Roads’ approach to Noise Management and Reviewing Road Traffic Noise Assessments may be obtained from the Environment Branch.

Table 2A – Noise level objective limits

 

Table 2B - Noise level objective targets

Notes for Table 2A and 2B: 

1. Noise is assessed 1.0 m from a building, 1.5 m above ground floor level.
2. Noise level objectives relate to the total traffic noise expected at a building facade, that is, noise from the Highway and any other road. (May need to include additional criteria for railways where the project includes construction of a railway).
3. Noise levels are recorded to the nearest 0.1 dB(A) and then rounded to the nearest 1 dB(A) for reporting and assessment against noise level objectives.

2.3.1 Pavement Surface Types

Vehicles generate noise either from sound pressure coming from tyres moving along a surface or from other sources such as the engine, exhaust and transmission of the vehicle. This section will deal with tyre/road noise of various surfacings. Basically the faster a vehicle drives the greater the tyre/road noise and at slow speeds (60 km/hr and less) most of the noise comes from the vehicle itself as opposed to the road/tyre noise. The merits of noise properties for each type of surfacing are listed below from the noisiest to the least noisy at the bottom.

• 14mm or 14/7mm seal – there is no discernible difference from the roadside between a single or double coat seal. For a driver the double/double seal seems to be less noisy within the vehicle.
• 10mm seal – marginally quieter from the roadside and much quieter within the vehicle.
• Microsurfacing – more quiet than a seal but noisier than DGA. It does provide a more comfortable ride for the driver.
• DGA and 10mm SMA – most noisy asphalt surface but quieter than microsurfacing or seals. These surfacings generate high levels of water spray particularly at high vehicle speeds. Therefore 10mm SMA is not recommended for high volume high speed roads such as freeways or Roe or Reid Highways
• 7mm SMA – more quiet than DGA but noisier than OGA. It also generates high levels of water spray particularly at high vehicle speeds which means it is not recommended for high volume high speed roads such as freeways or Roe or Reid Highways.
• OGA – quietest road surfacing used by Main Roads. Used on freeways and high volume highways plus roads where demand for skid resistance is high such as Greenmount Hill and Bindoon Hill. OGA generates low levels of water spray from vehicles at high speeds.

In relation to Austroads Table 2.2, Main Roads has identified the following relationship between different road surfaces. Refer to Table 2.2A.

 

Road Surfaces
Chip seal			Asphalt
14 mm	10mm	5mm	Dense graded	Novachip	Stone mastic	Open Graded
+3.5 dB	+2.5 dB	+1.5 dB	0.0 dB	-0.2 dB	-1.0 dB	-2.5 dB

Table 2.2A

3. Roadside Amenity

3.3 Landscaping and revegetation

For more detailed information relating to landscaping and revegetation practices in Western Australia refer to the guidelines for Revegetation and Landscaping.

For locations and site specific information regarding where Main Roads has completed revegetation and landscaping in the past please see our Revegetation and Landscaping Map.

3.4.2 Road Design Considerations for Rest Areas and Service Centres

For detailed information relating to Western Australian practices for Rest Areas refer to the Policy and Guidelines for Rest Areas.

Main Roads has developed a Strategy for Freeway Service Centres, and Guidelines for Rural Highways Service Centres (Roadhouses) outlining WA practices. For details contact the Road Planning & Development Branch.

4. Roadside Infrastructure

4.1.2 Signs, Markings and Delineation

For more detailed information relating to Western Australian practices refer to the Traffic Management guidelines and the Design of Guide Posts guideline.

4.1.3 Poles

For more detailed information relating to Western Australian practice for Pole Type Selection refer to Section 3.7 in the Lighting Design Guideline for Roadway and Public Space.

4.1.4 Traffic Signal Pedestals

For more detailed information relating to Western Australian practice refer to the Vehicular Signals guideline.

4.1.6 Fences

For more detailed information relating to Western Australian practices refer to the Design of Fencing and Walls guideline.

4.2 Road Lighting

For more detailed information relating to Western Australian practices refer to the Lighting guideline.

4.3 Emergency / Help Phones

For information relating to Western Australian practice refer to the Guidelines for Roadside Help Phones.

For detailed information relating to Western Australian practice on Emergency Stopping Bays refer to the Technical Guidelines for Emergency Stopping Bays.

4.5 Utilities

For detailed information relating to Western Australian practice refer to the Guidelines for Roadside Services.

5. Appendix

Appendix A - Examples of Post Selection Charts and Sign Support Gantries

For more detailed information relating to Western Australian practices and sign standards refer to the Sign Structural Design Guidelines.