The Safe System approach

Transport for NSW follows the Safe System principles for designing and managing roads and streets so death and serious injury is avoidable:

• We design and manage roads and streets so they are safe and forgiving. Safe roads and streets forgive mistakes. Safer vehicles can help reduce or absorb damage, but speed and environment play an important role in limiting death and serious injury too.
• People make mistakes. Road trauma should not be accepted as inevitable if a person makes a mistake when driving, walking or riding.
• People are vulnerable. Humans have a limited physical ability to tolerate crash forces and are vulnerable to forces greater than 30km/hour.
• Road safety is a shared responsibility. Road safety is a primary objective for all design practitioners, stakeholders and community members.

Safety is a result of environmental, vehicle and behavioural aspects across the whole system.

Please see the Safe Systems Assessment Framework for Movement and Place for more information.

Context-sensitive design speeds

Lower speed street design approaches aren’t used on motorways and highways. Applying the same logic, high speed road and highway standards are not appropriate for lower speed streets.

The design speed and changes in speed zoning of roads and streets should be set in accordance with the road or street type.

Speed limits

The design speed should match the posted speed on streets, and match the context on roads.

Aligning the design and posted speeds on streets with speed limited of 50km/h and below creates more self-explaining environments for people driving up to the appropriate speed.

Parramatta Road in Leichhardt performs poorly in both movement function and place intensity. Movement is often congested and inefficient, while the vibrancy of this space is constrained by narrow footways, fencing, and a lack of space for trees.

Barrenjoey Road Newport is also identified as an arterial high street. The street design in the town centre features distinctive street trees in the median and verge.

Changes in speed zoning

Use cues such built form, landscape, or intersections to locate the speed changes. For example, align speed zone changes where the suburban context changes to peri-urban, and again at the change from peri-urban to rural. The changes will then be more intuitive for road and street users rather than just regulatory, and this will help people to apply appropriate driving speeds.

On the the Newell Highway at the periphery of Narranderra, the change from a suburban to rural environment with an associated change from 50km/h to 110km/h is distinctly marked by an avenue of plane trees.

Separate space for people cycling

Separation should also be considered where either the volume of people cycling or driving motor vehicles is higher, even if the signposted speed is relatively slow.

In many areas where street space is limited, providing space for people to cycle may involve the physical reallocation of street space to achieve the place or network visions.

The Cycleway Design Toolbox provides examples of mixed cycleway facilities such as the quietway as well as separated facilities such as bicycle paths.

Higher speed roads can provide separated spaces for people to cycle on a long-distance cycleway through the vegetated verges of a motorway, or alternative along a cycleway located in an adjacent space that is more amenable for people to cycle.

On busy streets, such as Gadigal Avenue Waterloo, physically separated cycleways create more safe and comfortable conditions for cycling.

Crossing point spacing

Lower speed streets through town centres will have more regular, closely-spaced crossing points than higher speed roads. A very slow civic space or local street should be able to be crossed at any point.

On The Levee in Maitland, the destination high street is posted at 10km/h and people can comfortably cross anywhere along its length.

Street trees

Trees and plantings on roads and streets are vital for ecological reasons as well as to create comfortable conditions for people. Street tree plantings should be provided as appropriate to the context.

Street tree canopy targets for local street types

Street tree canopy targets for local streets.

These targets are based on research conducted by Gallagher Studio for NSW DPE.

Street tree canopy targets for other street environments

Street tree planting guidance for canopy

Guidance for tree plantings for verges and medians includes:

• Locate deep soil zones so existing significant trees are retained and healthy root systems are developed.
• Minimise barriers to tree growth by consolidating below-ground services and aligning services to paths, removing overhead cables and powerlines, and creating buffer zones.
• Where overhead powerlines are retained, locate street trees to allow tree growth in a balanced and healthy shape and minimise risk of pruning to an unnatural form.
• Preference street tree species with a minimum 8 metre canopy diameter to existing streets with overhead power and 10m to new streets with underground power to maximise canopy coverage. On narrower streets and lanes, smaller trees may be more appropriate.

Achieving a shady, leafy environment should be a key objective of road and street designers. Wolseley Grove Zetland is an example of a neighbourhood with significant street tree plantings, creating a more amenable, green, and valuable urban environment.

Street tree separation guidance for lower speed streets

Substantial street trees help reinforce a self-explaining, slower street. Trees also help protect and buffer people walking from general traffic and provide shade and cooling benefits for the urban environment. The health benefits for the community from substantial street trees are important to include in the assessment of project benefits.

On low speed streets (50km/h and below), street trees are a minor hazard. The selection and positioning of street trees should be mindful of ensuring space for root and limb growth, allowing people to walk and cycle freely, and avoiding conflicts with larger vehicles such as buses.

On lower speed streets such as Bourke Street Zetland, trees and other objects are expected to be present in the street space. Slower speeds allow increased time to stop as well as reducing the severity of vehicle collisions if they do occur.

Street tree separation guidance for moderate speed roads and streets

Moderate speed roads and streets often have many elements and objects in the environment and many intersections. TfNSW crash research has found that tree crashes are exceedingly rare. However, where land space is constrained, existing guidance includes wider clear zone dimensions (for example up to 5m for a 60km/h environment) that have the capacity to significantly minimise the provision of much-needed trees. In these situations, the location of trees needs to be considered early in the project to identify approaches that are appropriate for the context and provide greater public benefits.

On moderate speed roads and streets such as MacDonald Road Edmondson Park, current design standards are sufficient to allow trees to be located at a setback distance that allows for good shade and a generous number of trees in the corridor.

Street tree separation guidance for higher speed roads

Higher speed roads have higher consequences from collisions. In these situations, substantial trees require safety considerations such as setbacks, barriers, a differentiation between background and isolated hazards, and an awareness of situations where the risk of people losing control of their vehicles is higher. Tree setbacks should be based on the appropriate clear zone dimensions for that speed.

High speed roads such as the Hume Motorway near Woodbine need generous and forgiving setbacks for substantial objects. In some places a setback may not be able to be wide enough and barriers may be needed, which also require design for safety.