4.2.8 Specific Design Considerations
Freeways and interchanges
AS/NZS 1158.1.2 provides suggested warrants for the lighting of freeways and interchanges. However, the decision to provide lighting on these facilities and the form of lighting are matters for the road agency. Designers should therefore refer to local policy and guidelines and consult with the relevant jurisdiction.
The basic forms of service interchanges Austroads (2013a) such as diamond interchanges are likely to have a conventional lighting arrangement and depending on jurisdictional policy may be partially or fully lit. However, the lighting of large and complex freeway-to-freeway interchanges will require the services of an experienced and competent lighting expert and may require high mast area lighting rather than poles adjacent to carriageways.
Where roads cross freeways/motorways via grade separation without interchanging ramps, the crossroad should be lit to the standards applicable to the class of road involved and in accordance with AS/NZS 1158. However, when arranging the positioning of luminaires close to the freeway (i.e. over or under the freeway/motorway carriageway) care should be taken in the design and installation to ensure that any glare from the lights that may be experienced by drivers on the freeway is minimised.
This is usually achieved by avoiding positioning of luminaires directly above freeway/motorway traffic lanes (in the case of an overbridge) or by adopting an appropriate lower mounting height (in the case of a road underpass). It is usual to locate poles directly over the centreline of the freeway/motorway, or else directly over piers.
Lighting for off-street parking areas
Lighting of parking areas, access points and pedestrian areas should be undertaken in accordance with AS/NZS 2890.1. In addition, minimum lighting levels for open-air car parks, including rooftop areas should be designed in accordance with AS/NZS 1158.3.1.
Pedestrian and cycling facilities
The levels of lighting required are as defined by the light technical parameters in Table 2.1 and Table 2.2 for local roads and pathways of AS/NZS 1158.3.1.
The design for supplementary pedestrian lighting for mid-block crossings should comply with the requirements of AS/NZS 1158.4.
Standards for lighting paths for cyclists
Effective lighting is an important influence on travel on paths for cycling after sunset. As lighting involves significant capital and operating costs its provision needs to be carefully considered. While many bicycles may be equipped with modern lighting, it is generally inadequate to illuminate the pavement so that cyclists, travelling at a ‘reasonable’ speed, are able to avoid potholes and other hazards. The provision of lighting does not remove the need for providing a separation (centre) line.
The provision of public lighting on paths for cycling depends on the nature of the facility and its expected use at night. In general, lighting of bicycle facilities may be categorised as follows:
- Paths for cycling associated with promenades or some other centre of night-time activity. These are typically by the seaside, a river bank or in a city centre where a high standard of public lighting is desirable to create an attractive environment.
- Paths for cycling used predominantly for commuting by workers or students. Because it becomes dark relatively early in many Australian and New Zealand cities, commuter cyclists have no alternative but to ride during dusk, dawn or hours of darkness. Lighting of these paths may be justified if there is significant usage at night. Conversely, the lack of lighting may adversely affect the use of the path at night.
- Recreational paths, many of which are used primarily during daylight hours. The cost of public lighting is generally not justified. Designers should, however, consider whether a proposed path is likely to attract enough night-time use to warrant lighting, at least at locations of increased hazard.
AS/NZS 1158 provides standards for the lighting of urban roads and other public thoroughfares including shared paths. The United Kingdom and Europe, where bicycle usage may be higher than in Australia or North America, tend to provide higher levels of lighting as indicated in British Standard BS 5489-1:2013 and it may be appropriate to adopt this higher standard.
Roads which have roadway lighting to the Category V standard of AS/NZS 1158.1.1 will provide sufficiently for on-road bicycle facilities and will have enough surrounding illumination to provide adequate lighting of shared footpaths or bicycle paths located within 3 m to 5 m of the kerb and on the road side of the lighting poles.
The level of horizontal illumination needs to be sufficient for cyclists to easily follow the path, avoid potholes and obstacles, and to read surface markings (a minimum lighting level of 5 lux is required). An adequate level of vertical illumination should also make vertical surfaces such as fences, walls, kerbs, trees and shrubs visible. The overall level of lighting should enable cyclists to see other cyclists, read signs and also enable motorists to see cyclists where the path intersects a road or runs close to a road.
In the absence of significant experience in Australia and New Zealand on lighting levels for paths for cycling, Table 4.5 provides suggested lighting levels which should achieve the above objectives. The lighting levels provided accord with the American and Canadian guides. The levels suggested in the North American guides for tunnels, however, are considered to be excessive and the lighting levels shown in Table 4.5 are therefore based on experience with pedestrian underpasses in Victoria.
The levels listed in the table are for new installations. AS/NZS 1158 provides guidance on the appropriate maintenance factor to apply to the values in Table 4.5.
|Facility||Minimum average horizontal levels (lux)||Average vertical levels|
|Path for cycling||5||5|
|Cycle /pedestrian tunnel||< 10 m long||10||10|
|> 10 m long||20||20|
Where continuous lighting along a path is difficult to justify, it may be appropriate to light only the locations of increased hazard such as:
- intersections with other paths or roads
- sharp horizontal and vertical curves, and steep grades
- ramps to structures and at the portals of tunnels and subways
- where clearance to obstructions is minimal
- where pedestrian numbers are high
- locations which have special security problems
- special facilities such as stairs and bicycle parking.
Where it is proposed to continuously light a highly utilised path to the levels given in Table 4.5, special attention should be given to the above-listed locations of increased number of hazards to ensure that they are lit to above the average levels given in the table.
Higher illumination levels are generally desirable in pedestrian/cycle tunnels or underpasses to enhance cyclists’ personal security. It is also desirable to eliminate the temporary loss of sight experienced when riding from a bright into a relatively dark environment. For this reason it is usual to adopt a higher level of lighting in long tunnels during daylight hours and reduce the level at night when the contrast is less.
Vandalism can be a problem, particularly along paths in isolated areas and this should be taken into account in considering the provision of lighting and in the choice of luminaires. If lighting cannot be provided on a path, provision of a separation line and retro-reflective signs and markers will result in improved guidance for cyclists.