Are speed enforcement cameras more effective than other speed management measures? The impact of speed management schemes on 30mph roads.

This paper presents the results of an evaluation of the impact of various types of speed management schemes on both traffic speeds and accidents. The study controls for general trends in accidents, regression-to-mean effects and migration, separately estimating the accident changes attributable to the impact of the schemes on traffic speed and on traffic volume. It was found that, when judged in absolute terms, all types of speed management scheme have remarkably similar effects on accidents, with an average fall in personal injury accidents of about 1 accident/km/year. In terms of the percentage accident reduction, however, engineering schemes incorporating vertical deflections (such as speed humps or cushions) offer the largest benefits: at 44%, the average reduction in personal injury accidents attributable to such schemes, is twice that at sites where safety cameras were used to control speeds (22%) and they were the only type of scheme to have a significant impact on fatal and serious accidents. Other types of engineering scheme (with a fall of 29% in personal injury accidents) were on average less effective in reducing accidents than schemes with vertical features but more effective than cameras. All types of scheme were generally effective in reducing speeds, with the largest reductions tending to be obtained with vertical deflections and the smallest with other types of engineering schemes

The development of Scotland’s Curriculum for Excellence: Amnesia and Déjà Vu

Scotland’s new Curriculum for Excellence (CfE) has been widely acknowledged as the most significant educational development in a generation, with the potential to transform learning and teaching in Scottish schools. In common with recent developments elsewhere, CfE seeks to re-engage teachers with processes of curriculum development, to place learning at the heart of the curriculum and to change engrained practices of schooling. This article draws upon well-established curriculum theory (notably the work of both Lawrence Stenhouse and A.V. Kelly) to analyse the new curriculum. We argue that by neglecting to take account of such theory, the curricular offering proposed by CfE is subject to a number of significant structural contradictions which may affect the impact that it ultimately exerts on learning and teaching; in effect, by ignoring the lessons of the past, CfE runs the risk of undermining the potential for real change

The Cholecystectomy As A Day Case (CAAD) Score: A Validated Score of Preoperative Predictors of Successful Day-Case Cholecystectomy Using the CholeS Data Set

Background Day-case surgery is associated with significant patient and cost benefits. However, only 43% of cholecystectomy patients are discharged home the same day. One hypothesis is day-case cholecystectomy rates, defined as patients discharged the same day as their operation, may be improved by better assessment of patients using standard preoperative variables. Methods Data were extracted from a prospectively collected data set of cholecystectomy patients from 166 UK and Irish hospitals (CholeS). Cholecystectomies performed as elective procedures were divided into main (75%) and validation (25%) data sets. Preoperative predictors were identified, and a risk score of failed day case was devised using multivariate logistic regression. Receiver operating curve analysis was used to validate the score in the validation data set. Results Of the 7426 elective cholecystectomies performed, 49% of these were discharged home the same day. Same-day discharge following cholecystectomy was less likely with older patients (OR 0.18, 95% CI 0.15–0.23), higher ASA scores (OR 0.19, 95% CI 0.15–0.23), complicated cholelithiasis (OR 0.38, 95% CI 0.31 to 0.48), male gender (OR 0.66, 95% CI 0.58–0.74), previous acute gallstone-related admissions (OR 0.54, 95% CI 0.48–0.60) and preoperative endoscopic intervention (OR 0.40, 95% CI 0.34–0.47). The CAAD score was developed using these variables. When applied to the validation subgroup, a CAAD score of ≤5 was associated with 80.8% successful day-case cholecystectomy compared with 19.2% associated with a CAAD score >5 (p < 0.001). Conclusions The CAAD score which utilises data readily available from clinic letters and electronic sources can predict same-day discharges following cholecystectomy

Costing lives or saving lives: a detailed evaluation of the impact of speed cameras.

The real problem with speeding is that it is socially acceptable. Most drivers speed but are rarely involved in crashes. Police tolerance to marginal speed limit infringements is assumed, the likelihood of detection is perceived as low and fixed penalties are not considered particularly severe. High performance vehicles with speed capabilities well in excess of maximum national speed limits are not illegal but rather are considered a symbol of personal success. The result is that speeding is not perceived as dangerous, criminal or immoral but rather is considered the norm. Attempts to enforce speed limits tend to be unpopular, being viewed more as an infringement of personal liberty than as a curb on anti-social and potentially lethal behaviour. The evidence for the safety benefits of reduced speed is, however, strong. Certainly the basic laws of physics suggest that lower speeds will reduce both accident frequency and severity: lower speeds reduce both stopping distances and the energy dissipated in a crash. Available evidence does indeed confirm that both accident frequency and severity fall with reduced speeds (see, for example, McCarthy (2001), Stuster et al. (1998) and Taylor et al. (2000)). What is less clear is how best to ensure that drivers maintain safe speeds. While a wide range of approaches has been tried, speed enforcement cameras have undoubtedly attracted most public attention, frequently making headline news as, for example, happened recently following the publication of an evaluation of the UK national safety camera programme (Gains et al. 2004) Certainly for those responsible for road safety, speed enforcement cameras are seen as a way of increasing the perceived risk of prosecution for speeding and hence raising drivers awareness of the dangers, and the unacceptability, of excessive speed. However, although the rapid proliferation of cameras in recent years has undoubtedly increased the perceived risk of prosecution it has not fundamentally changed attitudes to the consequences of excessive speed. Critics have suggested that the primary objective of cameras is to raise money rather than to improve road safety and there have been claims that they may actually cost lives. While most of the criticisms of speed cameras are spurious (PACTS 2003, Mylius 2004), arising from a social climate that continues to consider the speed and the personal liberty afforded by cars desirable, the use of speed cameras continues to be controversial

Sources of error in road safety scheme evaluation: a method to deal with outdated accident prediction models.

This paper considers the errors that arise in using outdated accident prediction models in road safety scheme evaluation. Methods to correct for regression-to-mean (RTM) effects in scheme evaluation normally rely on the use of accident prediction models. However, because accident risk tends to decline over time, such models tend to become outdated and the estimated treatment effect is then exaggerated. A new correction procedure is described which can effectively eliminate such errors

Outcome measurement error in survival analysis

Available from British Library Document Supply Centre-DSC:DXN046163 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo

Effects on animal performance and sward composition of mixed and sequential grazing of permanent pasture by cattle and sheep

revious experiments have shown that mixed or conjoint grazing, when two or more animal species are grazed together, can lead to improved performance of one or more of the species and a higher total output per unit area. Sequential grazing systems, when different animal species graze an area in succession, also have the potential to improve productivity. This experiment directly compared these two approaches for integrating the grazing of cattle and sheep when pastured on improved permanent pasture. Four treatments were compared: 1) sheep only from May to October (S/S); 2) cattle only from May to July followed by sheep only from August to October (C/S); 3) cattle and sheep from May to July, sheep only for the rest of the growing season (C + S/S); and 4) cattle and sheep from May to October (C + S/C + S). Each treatment was replicated three times. From May until weaning at the end of July the plots were grazed by steers and ewes and lambs, and from weaning until October by steers and lambs. Sward heights were maintained at 6 cm using a “put and take” stocking system. Animal performance and sward composition data were collected during three growing seasons, 2001–2003. During the pre-weaning period lambs grazing plots which were grazed only by sheep had significantly poorer growth rates than those grazing plots where there was mixed grazing. Lambs grazing the sheep only plots also had lower liveweight gain during the post-weaning period, with the highest growth rates being recorded on the C + S/C + S treatment. Carrying capacity and total liveweight gain per unit area post-weaning were also consistently higher for the C + S/C + S treatment, while carrying capacity pre-weaning was highest for the C/S treatment. Measurements of clover content in the grazed horizon and botanical separation of material from quadrat cuts indicated that even under relatively controlled conditions choice of grazing system can influence sward composition. However, there was no clear link between any single sward change and the growth of the animals, indicating that the improved performance of cattle and sheep under mixed grazing is the result of a combination of factors, rather than a response to a particular sward parameter