Specific Techniques - Thorn Lighting


Specific Techniques - Thorn Lighting

Specific Techniques6.9 Lighting for crime preventionA firm body of evidence now exists to support the theory thatlighting can have a positive effect on crime prevention. Withthe increasing prevalence of CCTV cameras in shops andpublic spaces lighting also has an important role in aiding theauthorities in identifying suspects. These benefits however haveto be designed into a lighting installation, and it should beaccepted that improvements in lighting cannot overcome baddesign of structures or of a space. (For example the pedestriantunnel shown has untended shrubs, a perfect hiding place, andan overhang ideal for a person to hide on, even before thepedestrian has entered the blackness of the tunnel).Lighting can be used to affect two aspects related to crime• Actual crime. This is the act of a criminal event occurring.Lighting can either inhibit crime, or aid in the identificationof a suspect.Fig. 6.40 A forbidding entrance to a pedestriantunnel• The fear of crime. This is the mental worry of a criminal actoccurring. Fear of crime tends to be more prevalent than itused to be due to improved communications. Knowledgeof crime that occurs in a different geographical area caninduce fear of crime in a totally unrelated area, howeverirrational. Lighting can be used to create a safe andreassuring atmosphere.It is important to understand that when considering lighting fora space it is not always possible to understand the problemsof the space without seeing it in all conditions. Frequently thedaytime appearance is completely different to that at night.How can lighting be used as a tool in the fight againstcrime? Some general points can be made. For exterior areas,including car parks, light fixtures and fittings should incorporatevandal resistant features such as polycarbonate or reinforcedglass fittings with sources positioned out of reach. The effect oflighting should not be restricted, either by internal fixtures andfurnishings or by exterior structures or landscaping.Lighting columns/fixtures should not aid access, for exampleover perimeter fencing/walls. And cables and wiring servinglighting systems should be enclosed to restrict accidentaldamage or criminal attacks.Specific Techniques | 167

Specific TechniquesWhen lighting for crime prevention the main requirement oflighting is to ensure a high level of visibility and modelling. Itmust be understand that whilst precisely targeted increases inlighting generally have crime reduction effects, more generalincreases in lighting seem to have crime prevention effectsbut this outcome is not universal. However, even untargetedincreases in lighting generally make people less fearful of crimeand more confident of their own safety.To increase visibility and modelling requires consideration to theillumination on the vertical or semi-cylindrical planes. Pedestriansneed to be able to see other people clearly at a maximumdistance, to be able to perceive any possible threat, either fromfacial expression, posture or objects carried (such as a knife)allowing them sufficient time to react to the threat.When considering street lighting a change in design approachis required. Generally street lighting is designed for maximumefficiency, using the fewest lanterns/columns and switchinglanterns dependant on time. However, lighting should bedesigned for both road users and pedestrians, either by usinglanterns that have a high level of performance in lighting boththe road and paths, or with combined lighting units (Figure6.41), or by separate lighting units for each task. Lightingshould provide maximum quality and reduce shadows. Hence,lower wattage lamps spaced closer together are preferable,and lamp type should be chosen carefully to ensure a goodcolour of light and colour rendering (white light has beenshown to increase peoples feelings of security, whilst a lampthat obviously renders colour incorrectly reduces a person’sconfidence in the lighting).If lighting units are dimmed or switched off during the night highlevels of maintenance are essential as the failure of a lightingunit will have a larger effect if only some of the lighting units arelit compared with the case if all the lighting units were on.When lighting footpaths and cycle paths they should be lit ina manner that shows the direction that the path takes. Careshould be taken where necessary to illuminate beyond theboundaries of the path in order to increase the visual area andprovide more confidence to people using those routes. It shouldFig. 6.41 Combined lighting units with highmount lanterns and bollard heightlighting168 | Specific Techniques

Specific Techniquesbe recognised that steps and changes in level are also part ofthe path and they should not be considered as independentareas. In urban areas it is important not to rely on lighting fromcommercial premises to supplement the amenity lighting as if thecommercial lighting is switched off heavy shadows may occur.Lighting of commercial buildings should be controlled to preventhigh levels of illumination resulting in adjacent areas appearinggloomy or dark (as shown). For open areas such as parks orlarge pedestrian spaces the lighting should give guidance onthe configuration of the space.A specific hazard for footpaths are pedestrian tunnels. Thesegenerally have two problems, dark inside and light outsideduring the daytime, or light inside and dark outside during thenight. This has implications for visibility as the eye has to adjustto the different conditions which takes time, especially whenpassing from relatively bright light into darkness. The lightingneeds to be controllable to adjust to the different lightingrequirements (e.g. higher light levels during the day and lowerlight levels at night with lighting outside the tunnel matched tothe light levels inside the tunnel). As lighting units in pedestriansubways are generally accessible by the public they should bevandal-resistant and maintained to a high standard.Fig. 6.42 Façade lighting creating areas ofdeep shadowsCar parks should also be considered as pedestrian areas.N.B.;• Cars are generally stationary at entrance and exit points.Therefore these areas need higher lighting levels.• Special consideration should be given to stairwells, liftareas and areas with payment machines.• If possible light coloured surface treatments should beapplied to ceilings, columns and walls to maximise andreflect the effect of the lighting systemSpecific Techniques | 169

Specific TechniquesWhen lighting for CCTV cameras additional points needconsideration. To aid in the production of a good image thefollowing ratios should be checked;Ratio 1 = Upward horizontal illuminance Ideally Ratio 1 > 0.3Downward horizontal illuminanceRatio 2 = Downward horizontal illuminance Ideally Ratio 2 < 5.0Vertical illuminance towards cameraRatio 3 = Average luminance of subject Ideally Ratio 3 > 0.3Average luminance of background and < 3.0Ratio 4 = Vertical illuminance left Ideally Ratio 4 > 0.3Vertical illuminance right and < 3.0Ratio 5 = Vertical illuminance to the back Ideally Ratio 5

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