Wall tops: operational considerations for barriers and detectors

The last line of defence in preventing an escape from a high security prison is often a wall. Walls can prevent escape, by providing both delay and deterrence. However, without any reliable form of associated detection system then interception can only be fortuitous. A paper study of the types of walls used by European Prison Services was undertaken for the Prison Service in August 1993. Simultaneously, work was being pursued on the redesign of walls and wall top devices for the highest category prisons in England. Both threads of work amalgamated in an evaluation programme that included Government scientists, engineers, Prison Officials and UK industry. Several samples of wall top devices and height adjustments were evaluated to learn the cost effectiveness of delay. Meanwhile, work was progressing on the development and evaluation of detection systems for mounting on wall tops. An earlier development between Government and industry had produced a system that had good detection performance, a low false alarm rate but was not used operationally due to cost considerations. This paper will review the work to date concentrating on the evaluation of both the wall top devices and the detection system. It will address some strengths and weaknesses and will also look at some operational considerations.