Achieving a road network with safer speeds, or one where the travel speeds are unlikely to cause fatal or serious crashes, is one of the four elements of a Safe System approach, adopted by the NZ Transport Agency (‘the Transport Agency’). It is apparent that much of the New Zealand roading network is not safe at its current posted speed limit given the increased likelihood of fatal and serious crashes at high speeds. It is not affordable to upgrade most of the national roading network to achieve an environment where the current speeds are adequate. Hence, for the foreseeable future New Zealand will need to rely on speed management interventions for roads of winding terrain and/or low traffic volume. For existing road infrastructure this is achieved primarily by reducing operating speeds through speed limit reductions, rather than engineered solutions to achieve safer speeds. It is unlikely the public will accept a speed reduction to the levels where the fatal and serious crash risk is statistically low (eg less than 70km/h on undivided rural roads) and hence, the focus will be on reducing speeds to levels that drivers will accept and comply with. Purpose and objectives The purpose of this research was to assess the effectiveness of education, enforcement and perceptual changes to the road and road environment, to achieve acceptance of and compliance with lowered speed limits in both rural and urban environments across New Zealand. The key objectives were to: • undertake a focused literature review on relevant research from New Zealand and overseas • understand the current level of compliance in New Zealand with speed limit reductions • gain knowledge of New Zealanders’ attitudes to, and acceptance of, lower speed limits • assess the effectiveness of various levels of education, enforcement and road environment, and their impact on compliance with lower speed limits. Literature review There is considerable research supporting the road safety benefits of reduced speed limits. The most quoted being the power models of Nilsson (1984) and Elvik (2009), which show the road safety benefits of reducing operating speeds. Research collated by Austroads (2014) and Job (2014) in Australia on both rural and urban roads, also shows the total crash and causality reduction benefits of reducing speed limits by 10km/h and 20km/h can be in the order of 20% or more. There is limited literature internationally on the acceptance of and compliance with reduced speed limits, the main focus of this study. Most of the research focuses on drivers’ attitudes and their compliance with standard urban and open road speed limits and the move towards more enforcement of such limits. For many years European research has acknowledged and understood the fundamental benefits of speed limit reductions. A general attitudinal study in Europe found greater acceptance of lower speed limits in urban residential areas compared with extra-urban high-speed roads, where compliance with existing limits was already lower. A study into 80km/h rural roads demonstrated the importance of ensuring that road characteristics better matched the drivers’ perceptions of an appropriate speed limit. Road curvature and sight distances were strongly correlated with speed perception. The authors concluded, although there would never be a speed limit on a particular road section that would be credible for all drivers, there would be a speed limit that would be more credible for everyone. Anund and Svensson (2009) and Forsberg et al (2011) showed that, while people often disagreed with lower speed limits, a high proportion of respondents did travel slower subsequent to the changes and less than a fifth considered the lower speed limit had impeded the accessibility of the road. A survey conducted by Australian automobile clubs, demonstrated low acceptance levels of speed limit changes in the absence of background information and justification being provided to the community. A more definitive survey study showed that, in contrast to Europe, acceptance of lower speeds on some classes of rural roads was quite good, with less support for urban arterials and residential roads. When presented with some of the facts regarding the benefits of speed reductions, acceptance was higher, although likely compliance without matching enforcement levels might be less forthcoming. Compliance with speed limits The current level of compliance with reduced speed limits in New Zealand was assessed by looking at the results of ‘before and after’ studies carried out by various road controlling authorities across New Zealand. The assessment considered a range of different speed limit changes on urban and rural roads with different levels of traffic volume, alignment and roadside environment. The trial of speed zoning by the Transport Agency in 2005 and 2006 and recently reduced speed limits on the Otago Peninsula, show good compliance with reduced speed limits on winding hilly and/or mountainous rural roads. In most cases the speed limit applied was close to, or above the 85th percentile operating speed, so the interventions were targeting drivers travelling at speeds above those deemed safe for the conditions. The only concern with the new speed limits was on some roads there was evidence of speed targeting; ie where speed increased due to the speed limit being more achievable. The Hastings data showed that good reductions in travel speed can be achieved by reducing speed limits on certain local authority rural roads from 100km/h to 80km/h. Reductions ranging from 2km/h to 17km/h resulted, depending on the current operating speed. However, the Hastings experience also involved considerable opposition (poor acceptance) to these reduced speed limits. The acceptance web survey undertaken as part of the study supported this opposition, revealing there was very little support (9%) for a reduction in the general open road speed limit to 80 km/h, while there was some support (33%) for the more modest reduction to 90km/h. The application of reduced speed limits on high-speed, high-volume and high crash rate state highways was shown in the SH2 (SH1 to SH25) and SH1 Dome Valley case studies. The result of the speed limit reduction has considerably lowered the mean and particularly 85th percentile speed on both roads, especially in Dome Valley (where the speed limit was dropped to 80km/h — it was lowered to 90km/h on SH2). In both areas there has been a heightened level of police enforcement, given the high historical crash rates on these road sections. It is likely this police enforcement has contributed to the high reduction in operating speeds. The application of suburban 40km/h speed limits in Hamilton showed the biggest reduction in operating speed was generally as a result of engineering improvements. The installation of the speed limit signs and markings themselves had a limited impact on the operating speeds. The public’s opposition to the 40km/h speed restrictions programme for suburban streets in Hamilton has grown over time. This is consistent with the acceptance survey undertaken as part of this research, which showed there was little support for dropping speed limits on suburban streets below 50km/h. Acceptance web survey An acceptance web survey was conducted to understand drivers’ attitudes to safer (or reduced) speeds and received almost 250 responses. The survey was compared with other relevant surveys collected in New Zealand, Australia and the USA. When analysed by gender, females had much stronger support for safer speeds than males. The majority of drivers agreed that New Zealand roads would be safer if we all drove a little slower. There was also a high level of understanding that fatal and serious crashes are related to travel speeds. There was support for lower speed limits to reduce road trauma. The USA and Australian research also supports drivers’ understanding that speed does have an impact on the occurrence of a fatal crash. The USA research (2011), while not focused on lower speed limits, did provide a relatively detailed insight into drivers’ attitudes to speeding. A majority would prefer lower speeds as they feel less safe at higher speeds, which is similar to the New Zealand results. A large proportion indicated they drive faster so as not to hold up traffic, because they do not want to delay others. The solution supported by most was increased police enforcement of traffic laws, including speed limits, so that other drivers slow down and they can then drive slower without delaying others. This suggests increased speed enforcement, lower tolerance levels for speeding, and while not covered in the USA research, reduced speed limits. In the New Zealand survey, drivers’ acceptance of reducing speed limits in rural areas, suburban areas and in commercial areas was also examined. The strongest level of support was for 40km/h speed limits in shopping areas, the least popular being 80km/h speed limits on rural roads and 40km/h speed limits in suburban streets. See the table below for results of survey The acceptance web survey also showed that just under half of respondents would slow down if supplementary signage stating ‘safer speeds’ was posted to explain the reason for the speed limit reduction. If additional information such as ‘school’, ‘high crash site’ or ‘busy shopping street’ was added supplementary to the speed limit roundel, then even more respondents said they would slow down. This indicates that drivers would like affirmation of the reason for slowing down and want to see it displayed. Effectiveness of engineering, education and enforcement A variety of engineering measures have been used in conjunction with speed limit reductions around New Zealand. In urban areas the results indicated that engineering measures on wider roads, such as traffic calming, are much more effective at reducing operating speeds than the installation of speed limit signs and markings alone. This is consistent with the literature review findings. AA research (Turner 2014) also indicates drivers do not associate a high level of risk with roadside hazards and priority controlled intersections. On rural roads of a relatively flat and straight alignment, with a medium to wide cross-section, drivers expect to travel at the open speed limit. However many roads of this nature have a high crash rate due to the frequent occurrence of severe roadside hazards, frequent priority controlled intersections and high opposing traffic volumes. This was the case with many rural roads in the Hastings district, on SH2 (between SH1 and SH25) and SH1 through Dome Valley. On this type of road there is generally a low acceptance of reduced speeds, because the engineering of the road in terms of alignment and cross section, indicates higher speeds are possible. Despite low levels of acceptance of reduced speeds on such roads, there have been relatively good speed reductions, considering only the speed signage and some road marking was changed. This was consistent with the literature which indicated while there may be considerable opposition to reducing speeds, that once the new speed limits were introduced, many road users would comply with the lower speed limit. The impact of education, media campaigns and consultation practices of three speed limit reduction programmes across New Zealand was examined. The Otago Peninsula Safer Speed Area programme was a typical streamlined consultation and media programme. Of the three programmes it has had the least opposition. However this was attributed to higher levels of public acceptance of lower speed limits on gravel roads and narrow winding sealed roads. Extensive consultation and media campaigns were run by Hastings District Council and Hamilton City Council to introduce their respective safer speed areas. According to council staff at each authority, both programmes experienced considerable opposition from groups and individuals, which has grown since the reduced speed limit areas were introduced. In both cases, despite the extensive education programme, there seems to be a large section of society that does not understand the road safety benefits that justify the speed limit reductions. While some attempts were made (on SH2) to understand the impact of enforcement on compliance with reduced speed limits, the results were unable to be produced. This would have measured the impact of both active speed enforcement (using cameras) and passive police enforcement (through regular police patrols). Further research in this area is required to understand the impacts of enforcement. (Author/publisher)
Samenvatting