While WalkSydney and other groups advocate for 30km/h speed zones around Sydney, you may be interested in the Evaluation of 40 km/h Speed Limits, prepared for Centre for Road Safety, Transport for NSW, back in June 2017.

This independent evaluation, prepared by consultants for the NSW Centre for Road Safety, found that 40 km/h speed zones reduced road trauma by significant amounts.

The study looked at 40 km/h speed zones including High Pedestrian Activity Areas (HPAA), provided through a program funded by TfNSW since 2003 and implemented in partnership with local councils. Other permanent 40 km/h traffic management areas, for example in residential areas, were included where they could be identified. It did not include 40 km/h school zones. HPAAs take 40 km/h zones beyond those in local streets to busier road environments, to potentially provide more benefits in busier and more challenging traffic locations.

The purpose of the evaluation was to assess the effects of permanent 40 km/h speed zones in highly pedestrianised areas on road and roadside safety and on community amenity.

The strategic context is the Safe System approach, which acknowledges that road users will make mistakes and that the road system should be designed to accommodate these mistakes. Above 30- 40km/h the risk of death or serious injury in a pedestrian crash increases rapidly. A speed can be set below which the consequences of road user mistakes will not be death or serious injury.

Effectiveness was measured through analysis of traffic crashes by matching crash data with known locations of relevant 40 km/h zones. Also, workshops regarding HPAAs were held with practitioners in RMS (now TfNSW), local councils, and police. There were stakeholder interviews and a community survey with 498 respondents. A literature review was also undertaken.

Crash data analysis showed statistically significant reductions in crashes and casualty crashes on the HPAA and other types of 40 km/h zones.The trauma reduction benefits applied to overall crashes, not just vulnerable road users. While 40 km/h zones are intended to benefit vulnerable road users, in practice they improve safety more widely.

Zones implemented under the HPAA program were responsible for most of the casualty reductions measured in the evaluation. HPAA zones demonstrated greater percentage reductions in casualty crashes compared with other permanent 40 km/h zones and also included roads with a far greater number of pedestrian and other crashes therefore achieving far greater reductions in absolute numbers of casualties.

The results from the community survey indicated strong support for 40 km/h on busy roads where lots of people were walking. The creation of lower speed zones, such as through the HPAA, is associated with a number of other impacts in creating a road and roadside environment that supports increased pedestrian activity with a commensurate reduction in mobility for motorised traffic.

There was a predominant view amongst those implementing the HPAA program that speed limit changes in their own right are unlikely to achieve a reduction in speeds, and that greater use of physical engineering treatments is needed. The cost of these treatments and the perception that they are not suitable for arterial roads has constrained the application of 40 km/h speed limits. The majority of practitioners expressed strong views that 40 km/h zones without traffic calming would not work. However, the study states that where the road environment provides cues to a driver that it is an area of higher pedestrian activity, with narrow alignments or a well-defined urban precinct (such as the Sydney CBD), 40km/h limits should be feasible without geometric traffic calming (speed humps, chicanes etc).

It is recognised that roads have different roles. Some should provide safe, reliable and efficient transport within urban areas whilst others, with higher pedestrian activity and lower levels of vehicle movement should create places ofvalue for local communities and visitors. There is a significant challenge in addressing pedestrian safety on busy, vibrant streets, particularly arterial roads, which have demands for movement, while managing significant pedestrian activity.

The crash analysis supports the view that there is significant opportunity for expanded coverage to generate increased benefits,expanding speed limit zones below the urban default limit of 50 km/h, particularly where a location has a primary ‘place’ function.

The study raised the options of relaxing pedestrian crossing warrants (criteria) and trialling part-time zones that can allow the balance between movement and place to be altered at different times of day, or times of year.

For more details, check out

• The consultant’s report (June 2017): Evaluation of 40 km/h Speed Limits (Martin Small Consulting, PDF, 3.2Mb)

• TfNSW’s summary report (October 2018):Evaluation of Permanent 40km/h Speed Limits (PDF, 472Kb)