Injury Reduction Measures in Areas Hazardous to Pedestrians, Stage 2: Countermeasure Evaluation

Monash University Accident Research Centre – Report #178 - 2001

Authors: J.A. Oxley, K. Diamantopoulou & B. F. Corben

Abstract:

Victorians have enjoyed substantial reductions in the annual numbers of pedestrians killed after 1989. Despite these excellent gains, the overall problem remains a serious community concern with 76 persons killed and some 736 persons seriously injured in 1999. A large part of the savings appears due to a general downward trend in Victoria’s overall road toll after 1989. While pedestrians appeared to have benefited from measures targeted at drivers, pedestrian crashes in high activity/commercial centres still represent a long-standing problem for which few effective solutions have been found. It is suggested that innovative and comprehensive approaches are needed to moderate excessive vehicle speeds to uniformly lower levels in environments where there is high pedestrian activity. An evaluation was undertaken in areas known to be hazardous to pedestrians utilising a quasi-experimental before-after comparison of speed profiles and vehicle travel times following the implementation of speed moderating treatments. Large reductions of 7.5 km/h in average vehicle speeds over the full length of the treatment survey site were found. These were associated with estimated reductions of 2-3% in fatal pedestrian crashes and of 15% in serious injury pedestrian crashes. Mean speeds at locations within the survey site also reduced by 1.3 km/h. These reductions were associated with expected reductions of 11% in fatal, 8% in serious injury, and 5% in casualty pedestrian crashes. Furthermore, a significant reduction in the proportion of vehicles travelling at or above given speeds was found, particularly as vehicles entered the shopping precinct. In summary, this evaluation demonstrated that small gains in speed reduction can lead to very valuable gains in road trauma for pedestrians in environments where there is high pedestrian activity. Innovative countermeasures, such as those evaluated here, provide a cost-effective approach to moderate vehicle speeds, resulting in general benefit to all road users, especially pedestrians.

Executive Summary

Introduction

While Victorians have enjoyed substantial reductions in the annual numbers of pedestrians killed after 1989, pedestrian safety remains a serious community concern with 76 persons killed and some 736 persons seriously injured in 1999. Pedestrians have been identified as a group especially vulnerable to injuries sustained in a road crash and calls have been made to improve pedestrian safety through programs aimed at reducing the incidence and severity of crashes to all aged pedestrians.

Pedestrian crashes in high activity/commercial centres are a particular problem and one that needs to be addressed, however, few effective solutions have been found. There are a number of countermeasure options available for reducing the risk of death or serious injury to pedestrians in these areas. However, many of the traditional countermeasures have proved to be unsuccessful in terms of ensuring safe passage for pedestrians and this is reflected in little change in the rate of pedestrian casualty crashes.

The remaining alternative is to develop ways of achieving more moderate vehicle speeds. Indeed, past research provides a compelling case for moderating vehicle speeds in high pedestrian areas. Excessive speed has been shown to be a key factor in both the incidence and severity of pedestrian crashes and it has been shown that only small differences in travel speed can result in large differences in death and serious injury risk.

A concerted and innovative approach is required if real and lasting gains are to be made to pedestrian safety in Victoria’s hazardous commercial environments. Denmark and the Netherlands are known for their innovative and enlightened approaches to pedestrian safety and amenity, and some of their philosophies and practices were considered for application in Victoria and elsewhere in Australia.

Project Objectives

This research was conducted as part of a larger study to examine the possibilities for reducing injuries in areas that are particularly hazardous to pedestrians. The objective of this study was to evaluate some countermeasure options on arterial roads in the Melbourne metropolitan region. Specifically, the project aimed to:

Reduce serious pedestrian crashes, through the development of practical new approaches to moderating vehicle speeds, without seriously affecting travel times, and
Evaluate the effectiveness of recommended measures, so that the most cost-effective measures may be introduced at hazardous pedestrian locations in Victoria’s urban areas.

Project Design

This project involved the use of a ‘before’ and ‘after’ quasi-experimental design where speed profiles and vehicle travel times were compared before and following the implementation of speed moderating treatment(s) at one treatment site (Clarendon Street, South Melbourne) and one control site (High Street, Northcote).

The countermeasure treatments selected for evaluation were: 50 km/h speed limit and physical measures including painted pedestrian refuge between tram tracks, coloured crosswalks at intersections, and pram crossings.

Three surveys were conducted at both the treatment and control sites. During each survey time, free-flowing speeds at several points within the shopping strips and travel time information through the length of the shopping strip were measured. The first surveys comprised the ‘before’ survey when no treatments were installed. The first ‘after’ surveys occurred after a traffic control measure in the form of a 50 km/h speed zone was introduced on Clarendon Street. The last ‘after’ surveys occurred after a second set of physical countermeasures was installed on Clarendon Street.

Findings

At the outset, it should be noted that the quasi-experimental design was utilised in anticipation that this design would ensure that any observed effects of treatment implementation at Clarendon Street could be attributed to the treatments themselves rather than other factors. However, for this type of evaluation to be successful, an appropriate control site needs to be selected. High Street was chosen as the most suitable site, based on the factors indicated in previous sections. During the analysis of the data, however, some problems became apparent in the data collection at the control site, particularly regarding measurement of free-flowing speeds as vehicles left the survey site due to a tram crash upstream and equipment problems. Although the authors believe in the concept of this design, that it ought to provide a rigorous test of the effectiveness of treatment programs, there were some concerns about the reliability of the data collected at the control site. Moreover, to the knowledge of the authors, there was no overall change in speed behaviour in the Melbourne metropolitan area, nor was there any campaign launch aimed to target speed behaviour. There seemed to be no forthcoming explanations as to why speed behaviour had changed on High Street.

Considering these uncertainties regarding the reliability of the control data, an alternative approach is to assume that there was no system-wide change in speed behaviour in the Melbourne metropolitan area and examine the changes in speed behaviour and travel times on Clarendon Street without adjusting for control data. Furthermore, the findings of travel speed reductions were related to pedestrian injury risk.

Mean Speeds over the full length of the shopping strip

Average vehicle speeds were calculated from travel time data as vehicles entered and exited the survey site. Comparison of these data provided some encouraging results in terms of reductions in overall vehicle travel speeds. It seemed that installation of treatments resulted in sizeable reductions in average vehicle speeds throughout the shopping precinct. These reductions in average vehicle speeds were observed after all treatments were installed, compared to before treatment installation. Installation of the 50 km/h speed zone did not affect overall speed behaviour. However, average speeds were already below 50 km/h.$399.44

The overall reduction of 7.5 km/h in average vehicle speed throughout the shopping precinct was associated with estimated reductions of 2-3% in fatal pedestrian crashes and of 15% in serious injury pedestrian crashes.

Spot Speed Measurements at free-flowing locations through the shopping strip

While the large reduction in overall speed behaviour was encouraging, smaller but significant reductions in vehicle speeds at selected locations, in the order of 1-2 km/h, were found.

Reductions in speed of free-flowing traffic at spot locations of 1.3 km/h were associated with expected reductions of 11% in fatal pedestrian crashes, 8% in serious casualty crashes and 6% in casualty crashes.

Proportion of drivers travelling greater than specific speeds

The finding that proportions of vehicles travelling at speeds likely to kill or seriously injure a struck pedestrian, decreased as a result of treatment implementation, also provided strong evidence of the benefits to pedestrians.

The proportion of vehicles travelling at or above 60 km/h fell from 5% to 4% (i.e. a 20% reduction). Any vehicle travelling at or above 60 km/h is almost certain to kill or seriously injure a struck pedestrian.
The proportion of vehicles travelling at or above 50 km/h fell from 33% to 28% (i.e. a 15% reduction). Any striking vehicle travelling at 50 km/h has a probability of up to 85% of killing a pedestrian and 90% of resulting in a serious injury pedestrian crash. In terms of real numbers, this relates to a reduction from 240 vehicles every hour to 150 vehicles every hour travelling at or above 50 km/h and posing a significant threat to pedestrians.
The proportion of vehicles travelling at or above 40 km/h fell from 73% to 68% (i.e. an 8% reduction). Any striking vehicle travelling at 40 km/h has a probability of up to 26% of killing a pedestrian and a 66% probability of resulting in a serious injury pedestrian crash. In terms of real numbers, this relates to a reduction from almost 600 vehicles every hour before treatment installation to only 360 vehicles every hour travelling at or above 40 km/h.

Conclusions

This evaluation highlighted a number of important findings for pedestrian safety on Clarendon Street:

If it is accepted that speed behaviour did not change in the Melbourne metropolitan region throughout the study period, this evaluation demonstrated real reductions in vehicle speeds on Clarendon Street as a result of treatment implementation.
Overall reductions of 7.5 km/h (from 28.3 km/h to 20.8 km/h) in average vehicle speed throughout the shopping precinct were associated with estimated reductions of 2-3% in fatal pedestrian crashes and of 15% in serious injury pedestrian crashes. The smaller reductions of 1.3 km/h (from 44.9 km/h to 43.6 km/h) at locations where free-flowing traffic was measured are associated with expected reductions of 11% in fatal pedestrian crashes, 8% in serious casualty crashes and 6% in casualty crashes.
There was only marginal change in speed behaviour after installation of the 50 km/h speed zone, however, larger reductions in average and measured speeds throughout the shopping precinct as a result of installation of all treatments were found. This may provide some support to the suggestion that traditional countermeasures by themselves have limited success in reducing pedestrian casualty rates in shopping strip areas. An innovative approach that combines a range of countermeasure applications may be more successful in moderating vehicle speeds in areas of high pedestrian activity.
If the aim of treatments is to target those drivers that are exceeding the speed limit (i.e., those travelling at or above 50 km/h), the findings show a real effect of treatment implementation. This was particularly evident as vehicles entered the shopping precinct. Here, there was a 25% reduction after installation of the 50 km/h speed limit, and a 35% reduction after all treatments had been installed.
Travel times increased marginally, however, the large expected reductions in the crash risk of pedestrians as a result of reductions in overall vehicle speeds are considerable, while the impact on motorists travel times is relatively small.

Research indicates that small gains in speed reduction can lead to very substantial reductions in road trauma. The benefits of speed reduction can be related, not only to pedestrian safety, but there are general benefits to other road users including cyclists, motorcyclists and vehicle occupants.

Sponsoring Organisation: Baseline Research Program - Department of Justice, Transport Accident Commission, Royal Automobile Club of Victoria (RACV) Ltd, VicRoads