The Public Lighting Improvement Prioritisation System (PLIP) was developed after meetings between members and officers of Birmingham City Council in England to discuss street lighting improvements. PLIP is a weighted database using nine factors, each of which is divided into different classes with their own data sources, geographical weightings, and weights. The factors are: (1) night-time traffic accidents with personal injuries; (2) recorded crime; (3) population density; (4) other significant factors; (5) residents' details; (6) transport facilities; (7) public centres; (8) maintenance problems and vandalism; and (9) traffic flows. Factors are given for high, medium, and low weights, respectively. This article provides details of each of these factors, with explanatory comments, and outlines how the PLIP system was tested and is being applied. To ensure that PLIP has a workable life, PLIP was tested in the 1997 lighting improvement programme, to see what values the proposed streets would be given. The article gives a numerical example of the calculations. The initial proposal is to apply the PLIP system to the 1050 currently unmet requests for re-lighting in Birmingham. The second stage will be to apply PLIP to the whole city, a task with considerable challenges.
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