Measure type: Target hardening

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Target hardening is the measure of strengthening the security by increasing the required effort to commit crimes to or at an object.


Target hardening involves all measures that make committing a crime more difficult and reduce the opportunities for criminals to achieve their goal. Dependent on the type of crime the realisation of this measure can take quite different forms, ranging from teaching self-defence to possible victims of assault to bomb-proofing buildings against terrorists. In general the aim of target hardening is not to make objects completely resistant to attack, but to increase the risk of an attack for an offender (by for example increasing the time it takes to overcome the measures) to a level where the risk outweighs the gain of the crime as perceived by the offender.


Examples of target hardening can be categorised by the type of attack they oppose:

Against forced entry

  • Toughened glass (acrylic, polycarbon, etc.)
    Bullet-proof glass after a burglary attempt
  • Latticework or screens to cover windows
  • Deadbolt and vertical-bolt locks and door anchor hinges with non-removable pins
  • Metal door/window shutters
  • Tamper-proof screws in fittings
    Tamper-proof screw
  • Bollards and indirect routes against ramming
  • Vertical metal or small-mesh (unclimbable) fencing
  • Steeply angled roofs with parapets and ridges

Against destruction

  • Concrete or steel picnic tables, benches, bleachers
    Bus stop in Talinn, erected in hardened design after several vandalism incidents
  • Trash receptacles bolted to concrete bases
  • Hardened rubber or plastic swing seats
  • Fire-retardant paint
  • High-impact plastic or steel fixtures
  • Rough-play-tolerant adventure playgrounds
  • Slash-proof and steel-framed seats
  • Graffiti repellent spray on graffiti prone objects
  • Tamper-proof sign hardware and fasteners

Against bombs

  • Stand-off zones where no unauthorized access is possible
  • Increasing bomb resistance for vulnerable (parts of) objects
  • Locating vulnerable structures behind other, bomb-resistant or sacrificial structures

Against toxins and air-borne agents

  • Detectors
  • Closable air vents
  • Filter systems
  • Unreachable air intakes
  • Alternative air intakes
  • Emergency forced air circulation

Against violence

  • Separating traffic flows of for instance pedestrians and motor cycles to prevent snatch theft

Against all of the above

  • Early warning (alarms, emergency button) of action force or action force present
    Emergency button in Metro in Japan
  • Quick response of action force (by for instance optimizing access from police station to area)


This measure can be effective to a range of security issues. These are:

Financial gain Boredom or compulsive behaviour Impulse Conflict in beliefs
Burglary{{#info:Burglary is the crime of illicitly entering a building with the intent to commit an offence, particularly (but not limited to) theft.}} Physical assault{{#info:Assault, is a crime which involves causing a victim to fear or to experience any type of violence, except for sexual violence}} Destruction by riots{{#info:Destruction by riots is the act of vandalism of property by organised groups for a shared rational or rationalised reason.}} Mass killing{{#info:Mass killing is the crime of purposely causing harm or death to a group of (unknown) people in order to make a statement or to influence the public opinion. This threat is exerted out of wilful action by fanatics: terrorists or criminal activists.}}
Ram-raiding{{#info:Ram raid is a particular technique for burglars to gain access to primarily commercial premises, by means of driving -usually stolen- vehicles into locked or closed entrances, exits or windows.}} Sexual assault{{#info:Sexual assault is assault of a sexual nature on another person, or any sexual act committed without consent}} Destruction of property by fanatics{{#info:Destruction by fanatics is the crime of purposely causing damage in order to make a statement or to influence the public opinion.}}
Pickpocketing{{#info:Pickpocketing is a form of theft that involves the stealing of valuables from a victim without their noticing the theft at the time. }} Vandalism{{#info:Vandalism is the act of wilful or malicious destruction, injury, disfigurement, or defacement of property without the consent of the owner or person having custody or control.}}
Robbery{{#info:Robbery is the crime of taking or attempting to take something of value by force or threat of force or by putting the victim in fear. It is used her exclusively for acts committed to individual persons.}} Graffiti{{#info:Grafitti is the defacement of property by means of writing or drawings scribbled, scratched, or sprayed on a surface in a public place without the consent of the owner or person having custody or control. }}
Raid{{#info:Raid is the crime of taking or attempting to take something of value from a commercial venue by force or threat of force or by putting the victim in fear.}} Antisocial Behaviour{{#info:Antisocial behaviour is an accumulation category of relatively small crimes that highly influence the security perception of citizens. }}
Vehicle theft{{#info:Vehicle theft is the crime of theft, or attempt of theft of or from a motor vehicle (automobile, truck, bus, motorcycle, etc.).}}


General considerations

The realisation form of a measure should conform to the targeted public, threat level and surroundings: stand-off zones will be inappropriate in a shopping area and only deadbolted doors and windows are inappropriate for high-risk objects.

Urban planning considerations

Generally mechanisms for target hardening affect the scale of buildings and developments, as well as the micro-detailing of facades and streetscape furniture.

Urban planning techniques, such as land use analysis, can identify if vulnerabilities are present, and whether target hardening is an appropriate measure to consider in reducing the opportunity for criminal activity to occur.

If taken into account during the development process, urban planning considerations can aid in the application of target hardening measures that compliment development goals instead of harming them. An example of this could be where the detailing design measures applied to hardening shop frontages are changed to replace external roller shutters (negative connotations and attractors of crime) with equally practical, yet more aesthetic options, such as strengthened security glass frontages, that engender a better atmosphere[1].

Safety/security considerations

Target hardening measures aimed to improve security can have both positive and negative impacts on safety:

  • removing a door can harden a building against unauthorised entry, but can also reduce evacuation speed in case of emergencies such as fire
  • Replacing normal glass by toughened glass increases resilience both against security threats such as burglars, and safety threats such as tornadoes.

Social considerations

Resilience essentially includes societal resilience, and this is linked to citizens’ acceptance of security-enhancing measures. For that reason, security by design should as well consider the visible impact of security measures and should be unobtrusive as possible. This social aspect is of particular importance in relation to target hardening, which should consider that resilience cannot only be found in hazard-resisiting buildings but also in adaptive social systems.

It is also important to consider that design features of target hardening influence citizens’ perception of the risk that infrastructure is at, or that it is assumed to mitigate or prevent. Design features also influence the general perception of criticality of that infrastructure. These two are important aspects of security culture.

Furthermore, protective and resilience-enhancing measures directed at built infrastructure can have negative impact on resilience of social infrastructure and societal resilience. For example, research has shown that visible strong protective built infrastructure makes people to underestimate real risks and also makes them reluctant to adopt protective measures at individual and social levels, thus potentially undermining societal resilience.[2] Moreover, it must not be forgotten that resilience-enhancing measures are no substitute for continuously confronting citizens with risks, how to assess risks, and how to prepare for realisation of risks.[3]

Practical addressing of social aspects and aspects of security culture in security-related urban planning can best be accomplished by appropriately involving citizens, based on a set of introduced methods of citizen participation as compiled by VITRUV. Ideally, planning for the measure should include tests of usability of respective resilience-enhanced built infrastructure in relevant social contexts.

Economic considerations

Target hardening deters several types of security threats, mitigates the negative effects of these events, and also has some positive externalities like reducing fear of crime, and heating bills[4] (see the case example below). Target hardening measures, however, do require time and financial means by private agents, companies/developers and the public authorities, exacting economic costs. Together these benefits and costs are referred to as economic impact of security measures. The costs of surveillance measures contain the relatively straightforward direct expenditures on capital equipment and operational costs (both temporary and permanent), and in addition generate various types of secondary effects. These secondary economic effects are the result of subsequent rounds of expenditure ('re-expenditures') of business companies, households and public authorities outside the security market.

Whether the costs are making sense from an economic point of view, depends on many factors, and can be answered by two distinct sets of questions (see also the flow chart of an economic assessment):

  1. Are the envisioned target hardening measures cost effective from a socio-economic point of view, or are there better alternatives?
  2. Which specific agents (individuals, companies, sectors, authorities) are affected by the target hardening measures, and to which extend? How do the envisioned measures alter the behaviour of these agents, and, of course, the behaviour of criminals/terrorists?

Case example: A cost-benefit analysis of safer homes:

The Association of British Insurers (ABI)[5] performed a cost-benefit analysis on target hardening measures for home security. The analysis was based on the estimates of the average household cost of burglary (£3,300), the average cost of Security By Design (SBD) target hardening (£630), burglary rates (average 2.7 - 6.7% range), and socio-economic demographics. The per household net present value benefit of target hardening measures was projected over 20 years, yielding benefits of over £1,170 per household. As a result, the average household benefits are nearly double the average cost of the introduced security measures.

Economic tools can help decision makers to answer these questions and to prevent wasteful expenditures on security (of course in collaboration with insights from criminology, sociology, etc.). An illustrative example of efficient target hardening is sustainable design, since it combines energy efficiency with security and qualitative design. In contrast, target hardening measures like big concrete walls or window bars in retail areas are classic examples of measures which create an unwelcome environment. Instead these measures create an indirect economic impact as a result of a reduced perceived security and environmental quality.

Mobility considerations

Some target hardening measures work by limiting the mobility or accessibility to a certain location or area, for example by obstacles such as bollards, barriers or low speed roads with narrows. Though this helps to prevent certain crimes, it has a negative effect on the accessibility in general.

The other way around, in some cases it may help to increase accessibility in order to ensure that emergency services can reach an incident location as quickly as possible (see also incident mangement).

Routes between certain nodes are particularly vulnerable to crime, for example- homes that are on the route from a large bar may be vulnerable to vandalism and other types of minor disorder as well as to burglary. Planners can use this knowledge to help prevent crime when designing roads and accessibility routes in new communities.

Ethics considerations

Target hardening first requires the selection of those targets that are worth hardening. This involves ethics issues because limited resources will probably not allow addressing all relevant targets. This may lead to the creation of different levels of security in society. This illustrates the need to provide norms and standards beyond frameworks for built infrastructure.

Investigating human and societal needs regarding target hardening should be a priority. To support this, VITRUV offers a commented list of methods to determine ethics aspects in relevant urban planning.

Legal considerations

Legal considerations should include issuing of disclaimers since the proposed measures do not come with a guarantee for success. Duty of care aspects may also be involved. Target hardening as a measure to protect objects vs. as a measure to protect people may also involve different legal aspects. VITRUV offers a summary checklist and a list of methods to assess legal aspects in resilience-enhancing urban planning.

Footnotes and references

  1. Royal Borough of Kensington and Chelsea, Designing Out Crime, 2008,
  2. Dennis S. Mileti/John H. Sorensen: Communication of Emergency Public Warnings. A Social Science Perspective and State-of-the-Art Assessment. Oak Ridge, TN: Oak Ridge National Laboratory, U.S. Department of Energy, 1990.
  3. Dennis S. Mileti/John H. Sorensen: Communication of Emergency Public Warnings. A Social Science Perspective and State-of-the-Art Assessment. Oak Ridge, TN: Oak Ridge National Laboratory, U.S. Department of Energy, 1990.
  4. Source: Association of British Insurers (2006). Securing the Nation: The Case for Safer Homes.
  5. Association of British Insurers (2006). Securing the Nation: The Case for Safer Homes