B1. Street layout and crime

Permeability and burglary risk

Aims and method:

Focuses on the relationship between permeability of the street network and the location of crime. One police district in Merseyside (UK) is analysed was data collected at the street segment level, with 10,760 segments covered and correlated with police recorded burglary data, and adjusted for sociodemographic variables.

Key findings:

· Increased permeability is associated with elevated burglary risk so that burglary risk is lower on cul-de-sacs (particularly those that are sinuous – less permeable – in nature).

· The risk of burglary is higher on more major roads and those street segments that are connected to them.

Reference:

Johnson, S. D., & Bowers, K. J. (2010). Permeability and burglary risk: are cul-de-sacs safer?. Journal of Quantitative Criminology, 26(1), 89-111.

https://link.springer.com/article/10.1007/s10940-009-9084-8

Street connectivity and crime

Aims and method:

Examine geographical patterns of four types of offence behaviour: breaking and entering, larceny, vehicle theft and robbery. Crime data, at an address level across a 12-month period for the city of Ypsilanti, Michigan (USA) was mapped using GIS. A Space Syntax axial map was prepared using Spatialist software, and measures of street accessibility and visibility characteristics were examined in relation to instances of criminal behaviour, controlling for such factors as neighbourhood socio-economic status.

Key findings:

· Results of the analysis showed that both local integration and connectivity were highly associated with overall crime counts followed by density. Other factors such as median income, racial composition and global integration were not significant.

· Neighbourhoods that offered highly accessible routes to their residents apparently also offered criminals easy routes of escape, connectivity was significant at the 1% level (P= 0002).

· If there are higher levels of home ownership (indicating a more stable population), under conditions of high connectivity (supporting neighbouring and ‘eyes on the street’), crime is lower, while under conditions of low connectivity, crime is higher. Similarly, with high levels of youths in the neighbourhood, high levels of connectivity (supporting neighbouring and ‘eyes on the street’), are associated with lower levels of crime.

Reference:

Nubani, L., & Wineman, J. (2005). The role of space syntax in identifying the relationship between space and crime. In Proceedings of the Fifth International Space Syntax Symposium.

http://spacesyntax.tudelft.nl/media/Long%20papers%20I/lindanubani.pdf

Street layout and crime

Aims and method:

Addresses the relationship between crime and spatial design. The paper uses Space Syntax analysis to map spatial form and correlates this with crime (burglary) data in nine spatially different areas in British cities.

Key findings:

· Being in an integrated location reduces crime risk by 42%, but being in a highly connected space increases it by 31%.

· The overproviding of permeability where it does not increase integration – essentially the provision of permeability without use – is a security hazard in housing areas.

· Having any kind of secondary exposure (e.g. an exposed side garden wall) increases risk by about 38%, while having your entrance facing the front entrances on the opposite side of the road reduces risk by about 37%.

· Join buildings together, avoid any kind of secondary access, make sure that all public spaces are continuously ‘constituted’ by dwelling entrances, and maximise the intervisibility of these entrances by a linear rather than a broken up layout

Reference:

Hillier, B. (2004). Can streets be made safe?. Urban design international, 9(1), 31-45.

https://link.springer.com/article/10.1057/palgrave.udi.9000079

Layout, vitality and crime

Aims and method:

Studies the qualities of the built environment and their relationship with crime. Uses Space Syntax analysis to map five years of police crime data in a London borough with a population of 263,000, 101,849 dwellings in 65,459 residential buildings, 536 kilometres of road, made up of 7,102 street segments, and many centres and sub-centres at different scales.

Key findings:

· The relative safety of different types of dwelling is affected by two simple interacting factors: the number of sides on which the dwelling is exposed to the public realm - so flats have least risk and detached houses most, and the social class of the inhabitants.

· Higher ground level densities of both dwellings and people reduce risk, though off the ground density may increase it.

· Local movement reduces crime, larger scale movement (e.g. through movement) increases crime

· The principle that larger the numbers of dwellings on the street segment reduces the risk of burglary, applies both to cul-de-sacs and grid like layouts. Small number of dwellings in a cul-de-sac are vulnerable, especially if the dwellings are affluent.

· Mixed-use street segments are relatively safe with good numbers of residents, and vulnerable with few residents. Increased residential population neutralises the risk that is found with sparse residence on mixed-use segments.

· Higher rates of residential populations linked to streets are strongly associated with lower rates of residential burglary and on street robbery.

Reference:

Hillier, B., & Sahbaz, O. (2008). An evidence based approach to crime and urban design. Or, can we have vitality, sustainability and security all at once. Bartlett School of Graduates Studies University College London.

http://www.spacesyntax.com/wp-content/uploads/2011/11/Hillier-Sahbaz_An-evidence-based-approach_010408.pdf

Rear parking courts, lanes and crime

Aims and method:

Explores the literature relating to New Urbanism and crime prevention, and how the prescriptions of the new urbanists stand up to scrutiny against the criminology literature. The article encompasses a wide ranging review and comparison of the two literatures.

Key findings:

· Parking in rear lanes and parking courts in suburban residential areas have been associated with increased levels of crime, with more than half of all British domestic burglaries initiated from the rear of properties.

· More permeable residential street networks are also associated with higher levels of crime than less permeable configurations such as cul-de-sacs.

Reference:

Cozens, P. (2008). New Urbanism, Crime and the Suburbs, A Review of the Evidence. Urban Policy and Research, 26(4), 429-444.

http://rsa.tandfonline.com/doi/full/10.1080/08111140802084759?src=recsys

Layout, parking and crime

Aims and method:

Examines the impact of design on crime with a specific focus on housing developments acclaimed for their innovative design and award-winning architecture. The specific design features of thousands of homes were collated and assessed against police recorded crime data. The design features were based upon the key elements of Crime Prevention Through Environmental Design (CPTED) including road layout, house design, surveillance, territoriality, car parking, communal space, management and maintenance and physical security.

Key findings:

· True culs-de-sac experience the lowest levels of crime, followed by through roads (which experienced 93% more crime than true-culs-de-sac), with leaky culs-de-sac experiencing the highest levels of crime (110% more crime than true culs-de-sac).

· There is a clustering of crimes around footpaths, alleyways and access paths to properties.

· Rear parking courts are vulnerable to crime with higher levels of vehicle crime and criminal damage than other types of parking, and facilitate offender access to the rear of properties.

Reference:

Armitage, R., Monchuk, L., & Rogerson, M. (2011). It looks good, but what is it like to live there? Exploring the impact of innovative housing design on crime. European Journal on Criminal Policy and Research, 17(1), 29-54.

https://link.springer.com/article/10.1007/s10610-010-9133-8

Housing layout and crime vulnerability

Aims and method:

Examines the relationship between the spatial layouts of housing estates and urban areas and the spatial distribution of property offenses, based on Space syntax analysis and a year of crime reports provided by the police. The UK case studies cover a wide range of social classes: middle-high, middle-working and working-class housing estates.

Key findings:

· Other things being equal, property crimes tend to cluster in globally or locally segregated areas, particularly in cul-de-sac footpaths and rear dead end alleys.

· Also in short cul-de-sac carriageways which have sometimes been considered to be the key to increase local surveillance and hence to exclude casual intrusion by non-residents.

Reference:

Shu, CF. (2000). Housing layout and crime vulnerability. Urban Design International, 5(3-1), 177-188.

http://www.ingentaconnect.com/content/pal/13575317/2000/00000005/F0020003/9000016

Crime and characteristic British housing designs

Aims and method:

Seeks to explore the perceptions of three crucial user groups: planners, police officers and convicted burglars with regard to characteristic housing designs in Cardiff (Wales), Ten of each group were subjected to interviews based on their responses to photographic examples of housing environments.

Key findings:

· The findings suggest that the theory of ‘defensible space’ is clearly relevant and it is possible to enhance safety through design.

· Multiple dwelling units are routinely considered to be highly criminogenic and fear inducing, and possess significantly lower levels of defensibility than single dwelling units.

· In terms of the maintenance and appearance of each design, those manifesting visible ‘signs of decay’ were regarded as being notably more criminogenic, fear inducing and, significantly, less defensible than the well-maintained versions of the same design.

· The existence of an area dominated by vacant and derelict properties, of whatever design typology, is certainly ‘indefensible’, in several ways.

· The powerful socioeconomic associations attached to specific designs clearly influence the perceptions of burglars.

Reference:

Cozens, P., Hillier, D., & Prescott, G. (2002). Criminogenic associations and characteristic British housing designs. International Planning Studies, 7(2), 119-136.

http://rsa.tandfonline.com/doi/abs/10.1080/13563470220132218

Spatial factors and burglary rates

Aims and method:

Examines the effect of spatial factors on burglary distribution patterns in South Korea. Configurational factors were examined using space syntax analysis, and these were compared to burglary rates across six urban areas over the course of year (714 burglaries in total).

Key findings:

· Intelligible (legible) areas that are accessible to passersby, and thus used by more people, were less vulnerable to crime than less intelligible areas.

· Road type as a space structural factor had a closer correlation with burglary rates than any other factor.

· Burglary rates in Korean cities are highest in alleys with two lanes where there are high levels of pedestrian and vehicular traffic, located behind through roads.

Reference:

Chang, D. (2011). Social crime or spatial crime? Exploring the effects of social, economical, and spatial factors on burglary rates. Environment and Behavior, 43(1), 26-52.

http://journals.sagepub.com/doi/abs/10.1177/0013916509347728