The UK has over 35 000 primary, debris and security screens, intended to prevent internal blockage of culverts by debris and/or entry to a hazardous culvert. Historically some screens were constructed with insufficient justification, insufficient area or poor detailing, increasing flood risk and unnecessary safety risks to operatives, especially during high river levels. In 2019, Ciria's Culvert, Screens and Outfall Manual (C786) replaced the Environment Agency's Trash and Security Screen Guide and Ciria's Culvert Design and Operation Guide. The manual encourages assessment of the ongoing need for screens and, where they cannot be removed, to take a systems approach that considers the wider watercourse and catchment. This paper presents findings from early experience of using the manual on an Environment Agency programme to assess the continuing need for 92 screens in England. Early indications are that avoiding unnecessary screens and removing or modifying existing screens can improve safety, help natural sediment and debris movement along a watercourse, reduce operational expenditure and support the net zero carbon dioxide target and UN SDG 13: Climate action. It is recognised that every screen is unique and not every situation is covered by guidance. A novel design that reduces risk can be justified with documented rational analysis.

中文翻译：

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迈向更安全、更可持续的碎片和安全屏障

英国拥有超过 35,000 个初级、碎片和安全屏障，旨在防止碎片堵塞涵洞内部和/或进入危险涵洞。从历史上看，一些屏障的建造理由不足、面积不足或细节较差，增加了洪水风险和对操作人员不必要的安全风险，特别是在河流水位较高的情况下。2019 年，Ciria 的涵洞、滤网和排水口手册(C786) 取代了环境局的垃圾和安全滤网指南和 Ciria 的涵洞设计和操作指南。该手册鼓励评估对屏障的持续需求，并且在无法拆除屏障的情况下，采取考虑更广泛的水道和流域的系统方法。本文介绍了使用环境局计划手册来评估英格兰对 92 个屏幕的持续需求的早期经验的结果。早期迹象表明，避免不必要的屏障以及拆除或修改现有屏障可以提高安全性，帮助沉积物和碎片沿着水道自然移动，减少运营支出并支持净零二氧化碳目标和联合国可持续发展目标 13：气候行动。人们认识到，每个屏幕都是独一无二的，并且指南并不涵盖所有情况。可以通过记录的理性分析证明降低风险的新颖设计的合理性。