Crime-preventive spatial design

The goal of crime-preventive spatial design is to ensure safety through the design of public spaces. In the English-speaking world, this strategy has been used as Crime Prevention through Environmental Design (CPTED) for over 30 years and has had proven success in preventing crime and fear of crime, as well as in preventing terrorist violence. The fundamental idea of this strategy is that criminal opportunities to commit crimes and crime-related feelings of insecurity in the use of urban spaces are first created through planning and design. Knowing that not every criminal and terrorist attack can be prevented, urban crime prevention approaches aim to change crime opportunity structures. In this way, reducing the risk of crime in a particular location becomes an actionable goal that can be achieved with adequate resources. With such a target in place, simple and effective solutions can then be set in motion more quickly. After all, proper design and effective use of the built environment can lead to a reduction in crime and fear of crime, and thus an improvement in the quality of life. Finally, land use planning also has the goal of addressing social behavior and planning for sustainability. If criminal crime opportunities and fear spaces are created in cities, then they can be eliminated. Spatial crime prevention in its optimal perfection would be the art of preventing a would-be criminal from even considering committing a crime there because of the design of the space. A fear-free space would be a space to feel good and thus a space with quality of life and stay. In combination, this would be a free space without surveillance. Its fundamental openness, however, makes public space a target for attack, which terrorists consider attractive.

Events in public space are therefore secured by massive anti-terror barriers, which cannot be entirely avoided in view of the threat. However, what matters is a healthy mix between design and protective mechanism. Criminal activity, especially attacks on people or property, vandalism and theft, depend on the existence of opportunities to commit crimes. Their anticipation can be taken into account at the design stage. An effective prevention strategy therefore influences crime opportunity structures through spatial design or technical measures in order to prevent criminal activity or at least reduce the extent of damage.

The CPTED strategy is essentially based on three theories and approaches to explaining crime, which also provide important clues to the origin of terrorist violence:

• Rational Choice Theory
• Routine Activity Approach
• Defensible Space Approach

Rational Choice Theory

Rational choice theory focuses on the decision-making behavior of potential criminals, their utilitarian considerations prior to committing a crime. This approach is used as the basis for situational protection measures. Corresponding prevention approaches assume that offenders weigh up costs and benefits as part of their preparation for committing a crime in order to assess on this basis whether a crime is worth committing. For example, a potential criminal will consider whether he can be observed while committing the crime, how easily he can achieve the goal of the crime, and whether it is possible to escape undetected after the crime. With regard to terrorist attacks in public spaces, it is not only in the case of crossing acts that it is necessary to surprise the victims. The opportunity to enter the protected area unnoticed, to place an explosive device unobserved, could be a basic requirement from the perspective of an offender to plan an act at a certain location. The goal of the crime could be to reach a very high number of victims or to target specific victims. An undetected escape is always important for terrorist attacks if the perpetrators want to commit further acts afterwards. For acts of passion or large-scale suicidal attacks, perpetrators are more likely to include their own deaths by suicide or suicide-by-cop in the attack planning.

For example, a CPTED strategy to secure a public place against crossing acts could include the following prevention goals:

• Uncontrolled entry is prevented, and attacking vehicles can be detected early by visitors.
• Casualties are kept to a minimum by allowing visitors to avoid attacking vehicles.
• An attacker should realize that if he is attacked in a vehicle, he will be incapacitated and unable to escape, but preferably not killed.

With these goals, the crime opportunities and thus the crime success for a crossing act would be significantly minimized, and the affected space might not prove suitable from the offender's perspective.

However, rational choice theory also relates to the selection of the means of committing the crime. A large truck without GPS alarm monitoring, lane departure and brake assist systems, etc. is not readily available. This can only come into the possession of a perpetrator through elaborate and extensive preparatory acts. The situation is different with smaller vehicles, especially box/delivery vehicles. These are more readily available for a crossing act (in some cases with the engine running during delivery at the customer's address), and in some cases they were even in the possession of the perpetrators. The impact of the acts is not related to the size of the vehicles. For example, since 2017, only vehicles with a zGG of less than 3.5 t have been used for crossing acts in Europe.

Routine Activity Approach

The routine activity approach states that crime always occurs where three conditions coincide in space and time: motivated perpetrators*, opportunities to commit crimes, and the absence of an effective controlling authority. Crimes therefore occur when criminals encounter suitable victims or prey and protective forces are not present. (The old saying still applies: Opportunity makes thieves). Suitable from a crossing offender's point of view are victims in a location that is not secured and that does not provide an escape route for the victims.

Defensible Space Approach.

This space-theoretic approach involves the assumption that personal agency for safety in space will diminish as space becomes more public and thus more anonymous. If each person's responsibility for a space is clearly defined, action by that person that increases security could also be possible in semi-public spaces. The more intensely a person identifies a danger to himself or herself in a public space, the more willing he or she will be to act. As an example, consider a carny at a Christmas market who is aware of the danger of a drive-over offense and is more willing to report his observations to security forces out of personal self-protection, but also out of economic interest.

Collateral consequences

Consideration must be given to the unintended side consequences of a crime prevention strategy focused on situational control. A recurring objection to urban crime prevention approaches is that by influencing crime opportunity structures, crime is often only reduced locally, but beyond that it is primarily relocated or displaced. However, evaluation studies have shown that crimedisplacement is not a necessary consequence of urban development prevention measures. Instead, it could be shown that the selected prevention programs even had a beneficial effect on neighboring control areas or on other targets. Against the background of rational choice theory, such cross-target gains(diffusion of benefits) result, on the one hand, from the insecurity of potential offenders vis-à-vis an increased risk of detection and punishment and, on the other hand, from the subjective perception that committing crimes may no longer be worthwhile.

The routine activity approach emphasizes the importance of an effective control authority for the prevention of crime and terrorist violence. Thus, the visible deployment of massive police presence is intended to deter potential threats and symbolically communicate security. In the overall context of influences on the subjective perception of security, however, the findings of a study by the Berlin State Office of Criminal Investigation indicate that the visibility of police officers with machine guns at the Christmas market on Breitscheidplatz is predominantly considered to be of little or no help and that visible police measures play a rather subordinate role for visitors' sense of security.