Evaluation of Speed Limit Reduction on the Great Ocean Road

Posted speed limits on the Great Ocean Road (GOR) in Aireys Inlet and Fairhaven were reduced from 60 km/h to 50 km/h on 12 December 2022. An evaluation study was undertaken on the effects of this speed limit change using a case-control analysis methodology involving three evaluation criteria, as noted below. i. Change in community perception of safety a. Change in speed behaviour b. Change in user-reported road safety concerns and challenges c. Change in user-suggested changes to improve road safety ii. Change in speed a. Change in mean and 85th percentile speeds b. Change in compliance levels with posted speed limits iii. Change in near misses a. Change in gap size b. Change in Post Encroachment Time A combination of various survey methods and technologies (online survey, automatic traffic counters, and video cameras) were used for data collection before and after the change in the posted speed limits. • Online survey: to gather information on community perception of safety • Automatic Traffic Counters (ATCs): to collect spot speed, traffic volume, and classification data at 6 locations within Aireys Inlet and Fairhaven and a control site • Video cameras: to analyse near misses between vehicles and pedestrians through video recording of traffic movements at two locations Findings of Criterion 1: Change in community perception of safety Change in speed behaviour Survey respondents reported perceived improvements in driver behaviour with some mixed results in the surveys, but more respondents agreed driving speed was ‘slow or very slow’ and drivers ‘often or always’ drive too fast for the conditions. No substantial differences were observed in the proportions of respondents reporting other drivers following them too closely in both areas. Proportions of respondents felt that the cases where other drivers drive aggressively or overtake dangerously reduced after reduction of speed limits in both areas. The changes in perception of driving speed as ‘slow or very slow’ and other drivers ‘often/always’ driving faster than the posted speed limit were of higher magnitude for Fairhaven than Aireys Inlet. Overall, participants were divided on if the reduction in speed limits improved safety on the road. Change in user-reported road safety concerns and challenges The safety of pedestrians crossing the GOR appears to be a critical issue in both surveys. Other critical issues noted include the safety of bike riders using the road (before survey) and vehicles travelling too fast through town (after survey). Change in user-suggested changes to improve road safety More respondents were against speed limit reduction than in favour of it. With concerns of longer trips in the area, suggestions for varying speed limits (e.g., reduced speed limits during holidays and summer during peak times) were made by some. The need for more footpaths and concrete islands at pedestrian crossing points were also noted. Findings of Criterion 2: Change in speed After reduction of speed limits, the mean and 85th percentile speeds were reduced for most sites with relatively greater effects in Sites 1-4 (within Aireys Inlet) than Sites 5-6 (in and close to Fairhaven), and more drivers were speeding after speed limit reduction than before speed limit reduction, with relatively greater increases in proportions of high-risk speeders (those speeding by at least 10 km/h) in Sites 5-6. The mean speeds and 85th percentile speeds reduced in both directions of travel during school zone hours at Site 2 (located within the school zone and in close proximity to ‘Top Shops’ in Aireys Inlet). During the non-school hours, the mean speeds and 85th percentile speeds reduced for SB traffic at Site 2. Findings of Criterion 3: Change in near misses Change in near misses was examined using two surrogate safety measures: gap size and Post Encroachment Time (PET). Results did not show significant differences for both safety measures between the before and after conditions.