Mapping the impact of the Sydney lockout laws on assault

It has been well publicised that in February 2014 the NSW Government introduced legislation to try and curb alcohol related violence in the Sydney CBD and Kings Cross areas (see Liquor & Gaming NSW fact sheet). The intervention included lockouts and earlier closing times for licensed premises in the target precincts. In April 2015 the Bureau of Crime Statistics and Research (BOCSAR) released an evaluation of the intervention which found that since February 2014 (up to September 2014) there had been significant decreases in non-domestic assaults in the Sydney CBD entertainment precinct (down 26%) and the Kings Cross precinct (down 32%) (Menéndez et al, 2015).

BOCSAR now has crime data for a full year following the intervention which has allowed us to create hotspot maps showing how the concentration of non-domestic assaults have changed since the intervention.  The maps below show non-domestic assault hotspots for a 12 month period prior to the commencement of the lockout laws (2013 on Map 1) and a 12 month period after (April 2014 to March 2015 on Map 2). The maps draw on assault incidents recorded by NSW Police.

Download a pdf version - NonDVassault-Hotspots.pdf

The reduction in assault found in the evaluation is reflected in the April 2014 to March 2015 hotspot map when compared to the 2013 map. The same density scale was used in both maps so they can be directly compared.  This means, for instance, that on each map the colour black represents the same density of assaults. 

A comparison of the two maps shows:

• The high density (black) assault hotspot area along George Street decreased considerably in size from Map 1 to Map 2.
• The Kings Cross high density assault hotspot is still apparent but has also decreased in size.
• The density of the assault hotspot near Central Station has reduced and is no longer in the highest hotspot density range. The same is true of three other assault hotspots at  Taylor Square (Oxford Street), The Rocks and George Street near Wynyard station. 
• Map 2 shows a new hotspot of the highest density in Pyrmont (outside the intervention area) which is not apparent in Map 1.

How we build hotspot maps

Hotspot maps are a representation of the density of recorded criminal incidents per square metre across the target area. The target area for Hotspot Maps 1 and 2 was the Sydney city CBD. Hotspot Maps 1 and 2 were calculated using a 10m2 output cell (meaning we divided the target area into a grid of thousands of 10m2 squares) and a 250m search radius (meaning for each cell we looked for assaults occurring both in the cell and in the surrounding 250m). In the hotspot algorithm, incidents closer to the centre of the 250m radius have a higher weighting on the density calculation than those approaching the outer limits of the search area.  Every cell is then ranked according to its density score.  Here the most dense 75% of cells in Map 1 are displayed in colour on the map. Increasing density is represented by the progression of colours from shades of yellow through to black. Next, we applied the colour-to-density settings arising from Map 1 to the underlying density calculations for the second time period. This enabled us to create Map 2 on the same scale as Map 1.  It must be noted that incidents do still occur in areas which are not identified as hotspots.

Keywords: Lockout, alcohol, non-domestic assault, violence, crime mapping, crime maps, crime map, hotspot, licensed premises, crime density, trading-hours, Kings Cross, Sydney

References:
Menéndez, P., Weatherburn, D., Kypros K. & Fitzgerald, J. (2015). Lockouts and last drinks: The impact of the January 2014 liquor licence reforms on assaults in NSW, Australia. Crime and Justice Bulletin (no 183)

Updated 20 August 2015