**2. Materials and Methods**

This paper primarily adopts a descriptive case study with a multiple-case design that will require investigating the phenomenon in various cases [32] such as green street manuals and constructed projects for the analysis. The primary data source for this study consists of manuals dedicated solely to green street applications; only manuals with a specific focus on such projects have been selected so that the contexts to which they refer are rigorously related to green street implementation regarding objectives and design applications. The selected manuals were primarily created by the federal, municipal agencies, or related research foundation/organizations including the corresponding codes and ordinances. Manuals were searched by such key words as green street manual and green alley manual via search engines (e.g., Google and Bing). The search engines were more efficient than using any academic databases since they were not scholarly literature but uploaded to websites or databases created by governmen<sup>t</sup> or non-profit agencies. The primary manuals used here can be found in Table 3. In addition to the data from these manuals, data from site visits to constructed/in-progress green street projects were included, along with webpages and reports of green street cases from different cities and agencies, to ensure the breadth of the data used.




**Table 3.** *Cont.*

There were two sets of analyses: (1) A descriptive study of goals and objectives to investigate the breadth of benefits that can be generated by adopting green streets and (2) a descriptive study of green street design typologies focusing on stormwater facilities, which is one of prominent characteristics, to understand physical application of green streets within the right-of-way. An analysis based on phenomenological method suggested by Ratner [38] is conducted to identify accurate themes through multiple iteration by forming staged structures that require a rigorous analysis of the content of the data. All the contents related to objectives and benefits in the manuals were collected and "meaning units" [38], which contain specific meaning of a certain idea, were identified. Then, each identified meaning unit was summarized and grouped based on relative agendas (subcategory). The identified lists have been grouped and categorized again to ge<sup>t</sup> higher level criteria (top category) that can represent the lists that belong to the lower stage.

The definitions of a green street and general di fferences between green streets and typical streets were evaluated to understand the specific characteristics of green streets in the previous chapter. With the analysis, a closer look at the list of objectives in the green street manuals provided the basis for discussion about primary characteristics and the breadth of potential benefits for the surrounding communities. Typologies of green street designs applied to green street projects, especially those involving stormwater treatment facilities, were categorized according to di fferent design applications and locations where they were placed. Once the typologies were defined, a member check process was conducted with experts who worked on green street projects from governmental or non-profit agencies. The typologies were presented to the experts, whose feedback helped to modify and improve them to increase the validity of the created typologies. Overall, this paper aims to provide a comprehensive understanding of what green streets are and to work toward promoting green streets with consistent design approaches that can provide successful implementation with more benefits.
