我们需要对道路有不同的思考。

Linear roadway and street corridors are often constrained in approaches to providing traditional stormwater management (SWM) measures. Yet these corridors can make up about 40 per cent of the urban area of a large city and contribute most of the dry weather pollutants that impact our lakes and rivers. Corridor widths are often standardized by municipal requirements and determined by the required number of traffic lanes and standards for boulevard design, not by SWM requirements. The demands of the trafficked area are such that integrated runoff management systems inside the road corridor that would best approach a source control definition are discouraged or very short lived. The items best suited to addressing runoff management, such as large trees, are often viewed as obstacles or impediments to traffic design and flow management or they conflict with utility requirements.

绿色基础设施的方法的一个步骤right direction, but right-of-way dimensions and the required roadway functions can limit their effectiveness. In addition, most green infrastructure design approaches to existing roadways are retrofitted, with all of the built-in limitations that retrofits bring. An alternate approach that incorporates street character, corridor setting, and vehicle and active transportation functions is required to ensure runoff impacts from these urban areas is addressed in a manner that doesn’t impact the vehicle and active transport needs of the street users.

公共通行权中的分布式绿色基础设施解决方案还以支持城市传粉媒介栖息地的新植被,城市生物多样性的增加以及城市热岛影响的减少,为走廊带来更多好处。当开发桌面设计分析以狭窄的设计问题为重点时,这些好处往往会被忽略。

设计绿色街道

The Green Streets design approach that has been developed for the City of Toronto moves away from the concept of collecting roadway runoff with a storm sewer system and moving it to a central location, such as a SWM pond, as the only method to address precipitation impacts. It also removes the idea that certain classifications of roadway should receive similar approaches based on a potentially limiting set of previously approved measures or standards. A newer method that systematically determines which approaches to use based on street “reaches” (from intersection to intersection), its setting, its character, the population it serves, and the functions it provides, presents an opportunity to “dial in” performance while passively supporting corridor vegetation that is often otherwise neglected.

绿街的设计过程基于捕获与常见降水事件相关的小但反复出现的径流(即“雨水管理”)。这与较大但较不常见的暴风雨事件相反,这些事件在相对较短的时间内提供了大量降水量,并且需要传统的排水基础设施(即雨水管理)。

较小的体积但更常见的降水事件是年度降雨中最大的组成部分。例如,在安大略省南部,大约95%的降雨量减少了25毫米(mm)或更少的降雨深度。其中,有70%的事件下降了10mm或更少。这些事件可以在沿街道覆盖范围内的多个较小规模的区域中捕获和利用,然后在径流产生并将其定向到公共排水系统或接收水系统之前。这可以使用符合道路走廊但不阻碍其功能的分布式低冲击开发或营养系统来完成。将其视为一系列海绵。当暴露于较大的风暴时,这些分布式系统将仅溢出到排水系统。

绿色街道在许多方面与绿色基础设施设计重叠,但添加了步骤,以抢先确定适合街道功能的适当措施,避免陷阱创建系统以干扰交通和积极的运输性能。

绿街实施

The selection process begins with an inventory of surface and subsurface corridor features compared with municipally-prepared mapping of its natural features, including soil type and identified flooding hazard zones. It then follows a long-list approach to available runoff reduction and treatment options that mesh with and complement the street’s characteristics, resulting in a customized approach that integrates green infrastructure functionality into the street fabric. This process then leads directly into the conceptual design process followed by preliminary and detailed design and subsequent construction.

这种方法应用于多伦多的温内特和谢尔大街,这是两个具有不同街道特征的住宅街道地区。温内特大街(Winnett Avenue)是一条密集开发的单向街道,几乎没有林荫大道区域和不断的南部坡度。街上的房屋有小的前院,有许多树木,这些树木将受益于街道上的道路径流的被动灌溉。Schell Avenue是一条双向住宅街道,密度相对较小,但交通量较大。树木较少但更大,在较大的前码中,草皮区域较大。该过程有助于了解如何在不同的街道类型中实施绿色街道的过程,并扩展到主要的通道,动脉道路,目的地景点或“著名”街道。

At the north edge of Winnett Avenue, near a school block, where the boulevard area widened sufficiently, a bioswale treatment is planned for water balance and water quality treatment. It will be installed as a future project extension. Downgrade, where the street boulevard narrows and houses are present close to the street, a strip of permeable paving for parallel parking areas is being installed prior to oil/grit separator units for infiltration and water quality treatment. On Schell Avenue, the available boulevard area is elevated so a bioswale treatment for roadway runoff isn’t feasible and another strip of permeable pavement for parallel parking was installed. Oil/grit separators will perform backup water quality treatment prior to discharge to storm sewers.

The results of the installation include a significant reduction of annual runoff volume—a 91 per cent reduction for Winnett Avenue, and a 60 per cent reduction for Schell Avenue. The results also include retrofitted water quality treatment—78 per cent and 88 per cent TSS removal on an average, annual basis for Winnett and Schell Avenues. One-hundred-year event peak flow rate reductions of 16 per cent and 17 per cent in Winnett and Schell Avenues, respectively, from pre-project rates due to pavement net impervious area reductions were also realized.

案子

有一些类型的道路,绿街的实施最有效。由于基于浸润的措施的成本效益比,位于沙质土壤地区的道路走廊更适合绿街。同样,在林荫大道中,有绿色街道的林荫道中,绿色街道中有多个世纪的树木可以受益,这些树木被绿色街道的被动支撑,例如连续的土壤沟渠,每棵树的土壤量最低。具有较大外部排水区域的道路应绕过绿街设计周围的那些区域的径流,以避免用径流压倒它们。

However, municipalities will require high quality background and characterization of their roadway assets to allow for a systematic evaluation of how to apply these measures.

从降低城市热岛效应,避免未来下游基础设施升级成本以及改善街头角色的角度来看,减少和使用可用区域植被支撑的可用径流为被动区域植被支持提供了更大的投资回报。没有这些系统,下游接收水系统将需要吸收这些影响。

在设计补充街道功能的径流管理系统时,使用全参数考虑方法是一项具有挑战性的任务,它需要思考排水设计的直接问题。每条街道都需要一种自定义的方法,这些方法是从系统的考虑到其每个覆盖范围的个人特征的,而不是基于道路分类(本地,动脉,收集器等)的标准化方法。走廊设置将确定绿街方法有效的潜力,但是系统的方法将确保每条街道都能最大程度地提高其整体利益并最大程度地减少其径流的占地面积。

This article was written by Steven van Haren, manager of land development/water resources at加拿大的WSP, for the2021年7月/8月发行加拿大水新利体育app

标题图片来源:史蒂文·范·哈伦(Steven Van Haren)。

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