|Title:||Development of an index for assessing the pedestrian comfort of street environments in Hong Kong|
|Advisors:||Chau, Chi Kwan (BEEE)|
|Subject:||Streets -- Planning|
Pedestrian areas -- China -- Hong Kong
City planning -- China -- Hong Kong
Hong Kong Polytechnic University -- Dissertations
|Department:||Department of Building Environment and Energy Engineering|
|Pages:||202 pages : color illustrations|
|Abstract:||Walking has been actively advocated as a simple and effective means to boost individuals' physical activity levels. Comfort, which is one of pedestrian walking needs, is one of the major objectives employed by many street design guidelines and walkability audit tools. However, few methods or indices have been developed to evaluate pedestrian comfort by considering all the major built and micro-environmental factors. As such, the main aim of this study is to develop an index to assess pedestrian comfort of street environments in a holistic manner.|
The index formulation was initiated by identifying a list of major built and micro-environmental factors affecting pedestrian comfort for recreational walking. 420 questionnaire responses were analyzed together with the concurrently monitored micro-environmental conditions to formulate a path model that could portray the interrelationships among pedestrian comfort, and perceptual and objectively measured street built and micro-environment characteristics. The results suggested that pedestrian comfort was influenced by both objective and subjective perceptual built and micro-environmental factors. The influence of satisfaction of built environment involving sidewalks, amenities and landscape was found comparable to the aggregate influences of thermal sensation, perceived air quality and loudness. Thermal sensation, perceived air quality and perceived loudness have been found to mediate the associations between objectively measured parameters and pedestrian comfort for recreational walking respectively.
Next, multiple criteria decision analysis method (MCDA) was employed to develop a multivariate index for assessing pedestrian comfort by embracing thermal sensation, perceived air quality and noise annoyance (i.e. perceived loudness) as micro-environmental criteria, and sidewalks, amenities and landscape as built environmental criteria. This index targeted at assessing street segment as a basic analytical unit and was formulated by eliciting a set of importance weighting as well as indicators for individual comfort-related criteria.
Subsequently, the formulated composite index was applied to investigate the effects of morphological attributes in both street and neighborhood levels. The investigated street and neighborhood attributes were anticipated to exert influences on multiple comfort-related environmental factors on pedestrian comfort. The ultimate aim of the application of index is to provide insights for urban planners on improving pedestrian comfort of street segments. For street morphological attributes, tree-planting pattern, street orientation and aspect ratio, were studied. Tree-planting pattern and street orientation but not aspect ratio were found to significantly alter the pedestrian comfort levels of the baseline street configuration in Mongkok in Hong Kong. Tree-planting configuration with 4m or 8m-spacing yielded higher pedestrian comfort levels than the treeless throughout daytime, while the orientation that produced the most comfortable walking environment varied with time. More importantly, among micro-environmental criteria, thermal sensation was found to be the major criterion contributing to the differences in pedestrian comfort level among different orientations, tree-planting patterns or aspect ratios.
Finally, the neighborhood morphological attributes that were anticipated to significantly affect pedestrian comfort in a street segment was also investigated. This is of particular value as this study systematically explored the effects of neighborhood morphological attributes on pedestrian comfort of a street segment, which have not been fully explored in majority of neighborhood or area-scale studies. Given the unrevealed effects of neighborhood morphological attributes on the thermal comfort of a street segment and the considerable impacts of thermal comfort (i.e. thermal sensation) on pedestrian comfort stated in the previous section, this thesis revealed the effects of neighborhood morphological attributes on thermal comfort in a street segment before revealing their effects on pedestrian comfort. It was found that the hourly PET values and pedestrian comfort scores varied considerably with neighborhood morphological attributes, i.e. neighborhood compactness (BCR), surrounding building height configuration (SH/h ratio) and layout form.
For thermal comfort, taller surrounding buildings and/or more compact neighborhoods could help improve the thermal comfort conditions of both-side sidewalks. The close layout form could help improve the thermal comfort for E-W Street only. Their effects were found to vary considerably between E-W and non-E-W streets. Multivariate models have been formulated separately for E-W and non-E-W Streets to predict the hourly PET values based on neighborhood morphological attributes and microclimatic conditions. Based upon the PET values computed from the models, a series of charts have been generated to visually help determine the total number of comfort and very hot hours that will be yielded during daytime for a street being surrounded by different combinations of neighborhood morphological attributes. It was observed that a minimum of 3 comfort hours could be achieved when SH/h ratio ≥ 1.8 and BCR ≥ 47% regardless of street orientation or layout form.
For pedestrian comfort, a higher SH/h ratio would provide a more comfortable walking environment for all different orientations. The open and close layout forms would yield the best pedestrian comfort in Non-E-W and E-W Streets, respectively, while the BCR with the highest pedestrian comfort level varied with time for all orientations. Besides, it was found that thermal sensation was the most important criterion affecting pedestrian comfort for individual neighborhood morphological attributes.
Of particular value of the findings arising from this study is that the formulated pedestrian comfort index reports the pedestrian comfort levels in an hourly basis by taking into consideration of all major built and micro-environmental criteria. The index can assist urban planners in creating comfortable street environments, and pedestrians in making decisions to walk and choose comfortable routes.
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