Streetscapes and Walkability
October 28th, 2010, by Jeremy Krygsman
By presenting results in graphical format, analysis can be done to interpret and detect relationships between responses; in addition specific visualizations were proved to be preferred over others for their degree of greenery, and safety during both day and night. The remainder of this report will act as an evaluation and interpretation of these findings as they relate to the prevalence of greenery in urban environments. Discussions will focus on the survey utilized in the study, perceptions of greenery, as well as its impact on safety during the day and at night.
5.1 Survey Responses and Interpretation
As mentioned previously, the survey was arranged to randomize the videos as to decrease the chance of biased responses if the scale of greenery were to increase with each subsequent video. Organizing videos in the order of level 3, 1, 4, 2 was meant to encourage responses on an individual basis regardless of the previous video. In complying survey responses it was noted that individuals were quite hesitant to identify a video as very desirable; this may be the result of randomization as there was no common variable, or scale of increasing greenery to relate each response to. As such, each video stood alone and was based fairly on its specific degree of greenery and desirability, thus the risk of biased responses was in fact eliminated.
A limitation in the collection of data was that vendors and store owners were not included in the survey process; this may have indicated whether greenery may increase or decrease economic viability due to the foliage blocking store fronts and signs.
Relating back to figure 1, it was concluded that level 4 was the preferred option as it offered a higher level of greenery in contrast to the control (level 1). This preference is strongly related to the inclusion of greenery, with the combination of mature trees, planter boxes, hanging flower baskets, and lampposts that lead to a more desirable option to that of bare concrete. Reasoning for choosing level 4 as the preferred option is also provided in section 4.2, under the qualitative responses. A total of 27 participants had included a positive comment regarding the vegetation, or had stated that the vegetation was the primary reason for their preferred option. This relates to the cleanliness of the environment, increased aesthetics, ability to easily walk through the space, and a feeling of enclosure and safety from nearby automobiles. The majority of surveyees noted trees as a positive and desirable element that acted as a buffer and enhanced the streetscape.
Although visualization 4 was the preferred option, some respondents indicated level 1 and level 2 as their preferred option noting that the trees posed limitations to movement, causing feelings of entrapment and enclosure in the space. This conclusion indicates that greenery can also negatively affect a space and lead to undesirability, as some individuals prefer the sterile environment which the concrete provides.
Since the majority of Ontario cities resemble level 1 as streetscapes and inclusion of vegetation, most of the analysis will focus on level 1 in comparison to all other levels. Neutrality in responses was present as there was limited differentiation in the desirability of levels 1 to 3 and levels 1 to 4. This is illustrated in the Wilcoxon test, as the comparison of level 1 to level 3 had a significance of 0.001, however, the comparison between level 1 to level 4 had a greater significance of 0.000. Though these differences were highlighted in the Wilcoxon test, the impact is found within the Cohen‟s D values and effect sizes. In regards to level 1 vs. level 3, the Cohen‟s D value is 0.7299288, indicating a moderate/strong impact can be made with this level of greenery. This moderate impact is also present when comparing the greenery of level 1 to level 2. The Cohen‟s D value is 0.5871651 indicating that the inclusion of simple vegetation such as hanging baskets and planter boxes also creates a moderate impact on the streetscape. Though the impact of level 1 vs. level 4 is significantly stronger than level 1 vs. level 3 for vegetation, recommendations will conclude that level 3 would be the better option to implement. Reasoning for this choice is explained in the next section.
5.3 Safety during Day and Night
In reference to the box plots provided earlier, the preferred option during the day was level 4. Both the lower and upper quartiles of this visualization were above the indication of safe. Furthermore, the interquartile range of level 4 was the highest amongst all other videos. As seen in table 8, the Cohen‟s D values for level 1 vs. level 4 remain above 1.0 for all three tests (vegetation, safety during day, and safety at night) illustrating an immense significant difference. Before concluding that level 4 is the option that should be implemented, a review of the qualitative data highlighted that a large amount of trees would deter participants from walking in level 4 at night. It is these respondents that created the outliers found within the box plots, though it must be noted that level 4 received an overall perception of being safe (during the night) and even very safe during the day (as seen in figures 3 and 4). Qualitative responses indicated that trees acted as a buffer against the traffic during the day (increasing safety). However, the perception of level 4 changes during the night time. As portrayed in the box plot regarding safety at night (figure 10), level 4 has multiple outliers which represents the varying perception of safety for this visualization. Furthermore, the immense strength of difference shown by the Cohen‟s D value (1.2664393) does not indicate whether this impact is negative or positive during the night. By looking at the qualitative data, several participants stated that the trees blocked the light at night, and that they felt claustrophobia. This point was reiterated by Sally as she sated “I feel like someone is going to jump out at me. I don‟t like the trees, they block and make shadows and I can‟t see where people are.” Interestingly, the presence of trees were seen as a positive during the day, in that they created a buffer against traffic, however at night the vegetation blocked the light and decreased the visualization‟s safety. The alternative of level 1 vs. level 3 indicates that a moderate difference is present during the night with a Cohen‟s D value of 0.5079782 during the day and a value of 0.6342271 at night. Interestingly enough, at night level 1 vs. level 2 follows close behind with a Cohen‟s D value of 0.5550918. Interpreting this reveals that people may feel just as safe if there are planter boxes and hanging baskets as there are small trees (as in level 3). Due to the fact that level 3 has a strong/moderate impact in regards to vegetation and is perceived as neutrally safe during the night (show in figure 10 with interquartile range between 3 (neutral) and 4 (safe), level 3 remains the better alternative, as level 4 has extreme perceptions of safety during the night. This being said, as level 3 has a strong impact it can be considered safe both during the day and the night.
5.4 Relation to Literature
Let us recall the four key themes identified within our literature review:
- The importance of green space within urban environments due to the increase in urbanization and depletion of natural greenery,
- Health and safety of walkable spaces,
- The incorporation of green aesthetics to promote interaction, and
- Computer-based landscapes as a benchmark in urban design.
Theme 1: As mentioned during the presentation, it is a well-known fact that green spaces hold great importance within urban environments; however, there is a lack of quantitative literature to prove this theory. The research conducted in this report proved to be successful as a quantitative correlation between green spaces and walkability in an urban core was discovered.
Theme 2: Health and safety is another critical aspect reviewed in the literature and once again proved to be of importance through survey responses. Participants indicated that with increased vegetation their perception of walkability increased.
Theme 3: As inclusion of vegetation promotes walkability, this would increase the amount of social interaction if greater amounts of people are willing to be active in society. Furthermore, this could augment the social fabric and create a healthier community.
Theme 4: Computer visualizations were an effective tool as they gave the participant the chance to visually experience the environment as opposed to images, or a list of elements. The visualizations were also effective as they were an innovate tool to display the four alternating levels of greenery to participants.
Summary of Themes: As there is limited information regarding this subject, these findings prove the importance of including greenery in urban environments. It is noted that the degree to greenery should be carefully thought out so as to not obstruct ones vision during the day or the night.