CPTED & CPTEM Principles
Designing Out Crime
Harris Crime Prevention Services (Harris) applies the following definitions and explanations to the coined terms Crime Prevention Through Environmental Design (CPTED) and Crime Prevention Through Environmental Management (CPTEM).
Both initiatives encourage built form and public realm as ‘welcoming and safe place’.
Crime Prevention Through Environmental Design (CPTED)
Crime Prevention Through Environmental Design’s (CPTED) theoretical platform and principles were suggested by American architect and city planner Oscar Newman in the 1970s. He created the concept of ‘defensible space’. Criminologist C. Ray Jeffery developed the idea and coined Crime Prevention Through Environmental Design (CPTED).
They both wanted architecture and engineering to re-focus, re-emphasise and/or re-package elements of good urban design to achieve crime prevention objectives.
CPTED is also referred to as ‘safer-by-design’, ‘designing-out-crime’ or ‘security design’.
Harris has adapted five CPTED principles informing urban concept, master plan and design development briefs.
- Principle 1: Territorial definition – clarity about spatial identify, separation, boundaries and purposes,
- Principle 2: Natural surveillance – architecture facilitating strong sightlines for ground plane, basement and/or upper-level natural or passive observation (surveillance),
- Principle 3: Access control – access-egress definitions – who goes where, when and why,
- Principle 4: Activity support – the influences of (external) lighting, landscaping and signage,
- Principle 5: Target hardening – adding specific and robust architecture and technology.
CPTED Principle 1: Territorial Definition
Defining territorial boundaries, spatial separation and purposes is the first principle. The aim is to maximise built form and public realm ‘knowledge certainty’ for all who have day-night access to a site.
Stakeholder, occupant, visitor or contractor knowledge (identification) of territorial sub-spaces increases destination and circulation confidence; (for example, design of building entrances, public and communal spaces in mixed-use sites, sporting, retail, commercial or social gathering places, pedestrian corridors and vehicle entrances).
When ‘place’ form and function are easily identified, it removes confusion of purpose, enhances safe circulation and maximises alertness to any surrounding risks or threats.
CPTED Principle 2: Natural Surveillance
The principle of natural (aka informal or casual) surveillance encourages (i) the observation of built form and public domain spaces and purposes by user/stakeholders and (ii) the observation and notation within or around spaces of usual or unusual activity and behaviour, potentially (or actually) leading to anti-social or criminal threats and incidents.
Natural surveillance is purposeful observation. Maximum surveillance impact requires sightline certainty, facilitated by clear proximate-distant and longitudinal-latitudinal fields. The aim is to know who or what is within a surveillance field and to observe specific unlawful action or intent.
CPTED Principle 3: Access Control
Access control is a consequential extension of defining territory (Principle 1) and natural surveillance (Principle 2). Open and/or restricted access must be: (a) readily identified through the appropriate built form (approach) architecture, (b) supported by a physical access control system (pacs) and (c) able to prevent and/or identify unauthorised access.
CPTED Principle 4: Activity Support
Activity support applies (external) lighting, landscaping and signage architecture to a footprint’s form and function design, ‘supporting’ definitional clarity, passive and technical surveillance and access control.
CPTED Principle 5: Target Hardening
Target hardening is often called ‘situational’ crime prevention. It aims to reinforce other CPTED principles and to proactively ‘strengthen’ form, infrastructure, structures, fixtures, fittings and furniture in and around identified vulnerable spaces. Target hardening design is an added crime risk defence layer.
The aim is to increase the efforts ‘offenders’ must expend to disrupt legitimate occupancy and activity. Architecture is directed at denying or limiting access to potential criminal targets through more intentional design including electronic, mechanical, and physical means, such as camera surveillance security fencing, gates, locks and alarms. However, the design goal is to avoid ‘fortressing’.
Crime Prevention Through Environmental Management (CPTEM)
Harris Crime Prevention Services believes that there should be on-going oversight of ‘safe-place’ security. Harris has developed CPTEM as an oversight framework to complement and support CPTED.
The framework may be applied to most large mixed-use, single purpose and public realm sites and precincts. It would be implemented by facilities managers, building/site managers and/or security contractors in cooperation with stakeholder owners, operators, residents, tenants, contractors, councils and local police.
Over time, the purposes of developed built form, including public realm, may change. This in turn may lead to design and physical modifications. CPTED and CPTEM would therefore require review to ensure original crime prevention objectives are not compromised.
Harris believes that ad hoc and/or intermittent attention to CPTEM can negate CPTED’s effectiveness and can leave stakeholders exposed to harm or litigation in the event of threats or incidents occurring within premises or precincts.
Harris also believes that CPTED and CPTEM are interdependently linked. CPTED is intentionally integrated with concept, master planning and design development briefs. CPTEM is focused on post-construction operational ‘safe-place’ objectives and outcomes.
Harris has identified five CPTEM principles.
- Principle 1: Design Maintenance
- Principle 2: Systems Management
- Principle 3: Crime Risk Mitigation
- Principle 4: Incident Responses
- Principle 5: Monitoring and Evaluating
CPTEM Principle 1: Design Maintenance
Most physical and mechanical CPTED installations require regular maintenance. Lights, signs, landscaping, security doors, gates, fences and locks should receive scheduled maintenance and appraisal to affirm (design) purpose, capability and integrity. Repairs and/or replacements should be undertaken immediately when failures are identified.
CPTEM Principle 2: Systems Management
This involves the testing and management of security technology systems to ensure site-wide security and safety operational readiness. This includes physical (electronic) access control, alarm and IP Network (CCTV) surveillance systems. Regular scheduled testing for reliability, obsolescence, redundancy, replacement and re-alignment is essential, in some cases even mandatory.
Maintaining the integrity of security systems is also critical, when they are integrated with fire and emergency systems.
CPTEM Principle 3: Crime Risk Mitigation
Practical security awareness procedures should be developed to engage steward-stakeholders – owner-operators, security contractors, facilities and/or site managers of retail, residential, recreational, commercial, health, educational, industrial, transport and public realm premises and precincts.
Procedures could be similar to emergency, general office or body-corporate procedures. They should be understandable and practical.
Where warranted and practical, there should be scheduled ‘desktop’ crime risk assessments to build and manage ‘risk-change’ and risk mitigation options.
CPTEM Principle 4: Incident Responses
There are occasions when a ‘what-to-do-in-the event-of…’ scenario occurs.
Knowing how to identify and respond to anti-social and criminal incidents is critical. Security, facilities, site/building managers should develop and ‘rehearse’ responses covering the most common major or minor categories. Incident recording and reporting should be (i) factual, (ii) relevant, (iii) accurate, (iv) clear and (v) concise.
CPTEM Principle 5: Monitoring and Evaluating
Implementation of CPTED and CPTEM requires on-going regular monitoring and evaluation; to ‘test’ and share the relevance, cost-effectiveness and value (real and perceived) of both frameworks. This should lead to improving future security design (CPTED) and security management (CPTEM) outcomes. It may also mean that successful CPTED and CPTEM measures can be replicated and/or ‘modelled’ for future developments.