Walking, as a form of physical activity, provides substantial health benefits, such as reducing the risk of non-communicable diseases like heart disease and type 2 diabetes and combating obesity ((Adlakha & Sallis, 2020); (Li et al., 2021)). Walking also plays a critical role in sustainable urban development by reducing the impacts of urbanisation, including air pollution and urban heat islands (Tainio et al., 2021). However, despite these advantages, nearly 30% of adults globally do not meet the World Health Organization's (WHO) recommended 30 minutes of moderate physical activity daily (W.H.O., 2019). This issue is particularly pronounced in countries like Saudi Arabia and Kuwait, where inactivity rates exceed 50% (Guthold et al., 2018). Consequently, promoting walking through supportive urban environments has become a priority in public health, urban planning, and design (Barton, 2005).

The built environment is crucial for integrating walking into daily routines ((Zuniga-Teran et al., 2017)). The extent to which a neighbourhood-built environment supports walking—known as walkability (Southworth, 2005)—is determined by characteristics like residential density, street connectivity, and land-use mix. Enhancing these through urban policy and design is a proven strategy to promote walking (Frank et al., 2019). Over the past two decades, walkability has garnered significant attention due to its potential to improve health, environmental sustainability, and quality of life (Barker, 2012) (Gadais et al., 2018). Recognising the importance of walkability has led to integrating these principles into urban planning and design practices worldwide (Berghauser Pont et al., 2019).

To better understand walkability, key built environment characteristics have been identified as critical to supporting pedestrian activity. These characteristics include population density, diversity of destinations, and pedestrian-friendly design—often collectively known as the "3 Ds" (Cervero & Kockelman, 1997). In practice, a fourth factor, "distance," also plays a crucial role (Townshend, 2022). Researchers have expanded on these categories by subdividing them into macro-scale and micro-scale characteristics (Sallis et al., 2011) (Ledraa, 2015). Macro-scale characteristics include (i.e. residential density, land-use mix and intensity, street connectivity, and retail density) (Leslie et al., 2007) (Sallis et al., 2016) (Zandieh et al., 2019). In contrast, micro-scale characteristics, such as safety, pedestrian infrastructure, and aesthetics, affect specific route features within a neighbourhood. Despite these reclassifications, the core argument remains consistent.

This distinction between macro-scale and micro-scale characteristics is critical for understanding how the built environment influences different aspects of walking. Macro-scale characteristics have a long-term impact and are often resistant to change after urban development (Shafieiyoun & Zamani, 2021), shaping neighbourhood design and influencing micro-scale characteristics, thus affecting pedestrians' decisions to walk for various purposes, such as commuting and recreation. This reflects Jane Gehl’s public space and public life theory ((Fonseca et al., 2021); (Saelens & Handy, 2008)), which classifies activities into necessary (i.e. commute walking), social and optional (i.e. recreation walking). Different types of walking are linked to various built environment characteristics: both commuting and recreational walking are related to macro-scale characteristics (Hirsch et al., 2014) (Saghapour et al., 2019), while micro-scale characteristics are found to influence only recreational walking ((Fonseca et al., 2021); (Saelens & Handy, 2008)). These connections underscore the importance of macro-scale characteristics in shaping walking behaviours and activities within neighbourhoods.

Research has shown that populations in neighbourhoods with high walkability report nearly twice the total weekly walking compared to those in low-walkable neighbourhoods (e.g. (Kärmeniemi et al., 2018)). These findings suggest that variations in neighbourhood macro-scale characteristics are associated with differences in walking behaviour. High-walkable neighbourhoods, by offering proximity to destinations and activities (Gao et al., 2020), are likely to encourage more walking (Wang et al., 2016). However, the role of microclimate—particularly its effect on outdoor thermal comfort—has received less attention in walkability studies despite its significant influence, especially in hot-arid climates. This oversight raises important questions: Do residents in low-walkable neighbourhoods face greater challenges in terms of thermal comfort compared to those in high-walkable areas? How do different levels of walkability impact thermal comfort? What urban planning and design strategies can simultaneously enhance walkability and thermal comfort in hot-arid environments? Addressing these questions is crucial for urban planners to identify and mitigate the factors contributing to walkability deficiencies in less walkable neighbourhoods.

Microclimate characteristics significantly affect walking activities and comfort. Environmental characteristics such as air temperature, mean radiant temperature, wind, and humidity influence outdoor thermal comfort. In regions like Buraydah, extreme temperatures can impact the feasibility and desirability of walking ((Chen et al., 2023); (Cleugh & Grimmond, 2012)). Air temperature and mean radiant temperature directly affect thermal sensation, while wind and humidity modify these sensations by influencing the body's heat exchange processes ((Azegami et al., 2023); (Li et al., 2018); (Sangkertadi & Syafriny, 2016); (Yin et al., 2019)). Personal characteristics (i.e. clothing levels and metabolic rate) also determine an individual's tolerance to varying thermal conditions ((Colom et al., 2019); (Mitra & Faulkner, 2012)). Studies on the relationship between microclimate and walking have yielded mixed results, depending on climate: in cold regions, walking activity increases in summer, while in hot regions, it often declines (Hino et al., 2021) (Shaaban et al., 2018). Understanding thermal comfort in relation to walkability is thus crucial for encouraging walking across diverse climates.

This study applies specific criteria to identify walkable and thermally comfortable neighbourhoods in Buraydah City, Saudi Arabia, to address these questions. Objective characteristics such as urban growth patterns, population density, and land surface temperature (LST) will be used as proxies for walkability and thermal comfort. Urban growth patterns influence the quality of walking routes (Mouada et al., 2019), and well-planned urban growth enhances connectivity, making walking more convenient (Won & Jung, 2023). Population density often correlates with accessibility to amenities, enhancing walking opportunities (Gao et al., 2020). LST, influenced by factors like green spaces and building materials, affects thermal comfort and is further impacted by the urban heat island effect (Won & Jung, 2023). These characteristics contribute to spatial heterogeneity, impacting walkability and thermal comfort.

Macro-scale neighbourhood characteristics can be assessed objectively or subjectively. Objectively measured characteristics may not always align with individual perceptions of the environment. Behaviour change theories suggest that perceived built environment characteristics may correlate more strongly with health behaviours than objective measurements (Sallis et al., 2015). Subjectively measured characteristics reflect personal evaluations of the built environment, shaping the lived experience and influencing whether people perceive their neighbourhoods as walkable (Arellana et al., 2020). For instance, a diverse land-use mix, street connectivity, and retail density could enhance walking by providing varied destinations within walking distance and making walking more efficient and appealing (Hakimian & Lak, 2016).

Many studies on outdoor thermal comfort have developed universal indices to characterise comfort in both hot and cold climates. The primary indices include PET (Physiologically Equivalent Temperature), PMV (Predicted Mean Vote), UTCI (Universal Thermal Climate Index), and SET* (Standard Effective Temperature), all suitable for calculating heat and cold stress (Binarti et al., 2020). PMV classifies thermal sensation, while PET, UTCI, and SET* evaluate thermal comfort in degrees Celsius. PET, initially developed for Western and Central Europe, has a "neutral" scale of 24–26°C for hot climates, confirmed by 95% of studies (Matzarakis & Amelung, 2008). In cold climates, 89% of studies identified a neutral range of 15–20°C. Research in tropical climates, such as Taiwan and Egypt, reports higher PET values than those observed in Europe (Lin, 2009) (Mahmoud, 2011), indicating that local urban climatic characteristics influence thermal perception and outdoor environment use.

Since neighbourhoods are integral to daily life and outdoor activities and vary with climatic conditions, associating thermal comfort with walkability could improve the creation of environments that support walking year-round (Peca Amaral Gomes et al., 2021). A pedestrian-friendly built environment can be achieved by implementing urban standards and continuously assessing walking conditions (Alawadi et al., 2021). Previous research has linked outdoor comfort to various built environment characteristics (e.g. (Jia & Wang, 2021); (Labdaoui et al., 2021)). Despite advancements in measuring walkability, several practical issues related to pedestrian comfort remain unresolved, including 1) the absence of thermal comfort measurements at the neighbourhood scale and 2) the assessment of walkability considering thermal comfort. Therefore, building on prior research, this study aims to investigate the relationship between walkability, outdoor thermal comfort, and walking behaviour in Buraydah City, Saudi Arabia, focusing on walking frequency, duration, and PET values. Incorporating thermal comfort into walkability assessments at the neighbourhood macro-scale is essential for creating walkable and comfortable neighbourhoods. This study adopts a holistic approach by considering both measurable environmental characteristics and subjective experiences, using PET to evaluate thermal comfort—which is crucial for fostering year-round, sustainable walking behaviour.

This empirical study, conducted in September 2023, focuses on Buraydah, a mid-sized Saudi Arabian city with over 700,000 residents (Saudi General Authority for Statistics, 2023), characterised by a hot-arid climate (BWh) according to the Köppen climate classification (Peel et al., 2007). It investigates the relationship between walking behaviour, neighbourhood walkability, and outdoor thermal comfort. Data collection involved surveys, microclimatic measurements, and Geographic Information Systems (GIS) analysis across three high-to-low walkable and comfortable neighbourhoods. The study aimed to understand how these characteristics collectively influence walking behaviours under Buraydah City's unique climatic conditions.

This study investigated how spatial variations in high-to-low walkable and comfortable neighbourhoods—considering urban growth patterns, population density, and land surface temperature—affect perceived walkability, walking behaviour, and outdoor thermal comfort (PET) in Buraydah City, Saudi Arabia. Consistent with previous research ((Jia & Wang, 2021); (Mouada et al., 2019); (Tan et al., 2018); (Wang & Yang, 2019)), this study found that participants from high-walkable and comfortable neighbourhoods walked more and had lower PET levels than those from low-walkable and comfortable neighbourhoods. These findings emphasise the importance of walkable environments in promoting physical activity. Additionally, the lower PET levels observed in high-walkable neighbourhoods suggest that urban characteristics such as shaded streets and proximity to various amenities can enhance outdoor thermal comfort and make outdoor walking more feasible, especially in hot climates.

The positive association between perceived neighbourhood characteristics—including land-use mix, street connectivity, land-use intensity, and retail density—and total daily walking aligns with the broader literature on walkability. These characteristics are crucial in shaping the perception of neighbourhood quality, which subsequently influences walking behaviour (Sallis et al., 2016). Interestingly, perceived walkability was also inversely related to estimated PET, suggesting that well-designed, high-density environments can contribute to outdoor thermal comfort by offering shaded areas, reducing exposure to extreme heat and providing cold spots at a close distance (e.g. shops), allowing for more relief from the extreme heat. This relationship was more pronounced in high-walkable neighbourhoods, where higher density and mix of uses contribute to higher walking levels and improved thermal conditions. These findings are in agreement with the work of ((Mouada et al., 2019); (Won & Jung, 2023)), who reported similar associations between neighbourhood characteristics, walking behaviour, and thermal comfort.

However, when individual neighbourhoods were analysed separately, significant relationships between perceived neighbourhood characteristics and PET were not observed. This suggests that while overall walkability may enhance outdoor thermal comfort, the effect of individual neighbourhood characteristics on thermal conditions may vary across different local contexts. The lack of significant findings could also imply that subjective perceptions of thermal comfort are influenced by a complex interplay of factors, including microclimate elements, personal comfort preferences, and social norms, which may not directly correlate with physical neighbourhood characteristics. This highlights the need for urban planners to consider objective and subjective characteristics when designing interventions to promote walkability and outdoor thermal comfort.

The study’s findings also support the idea that perceptions of the built environment influence walking behaviour. High-walkable and comfortable neighbourhoods positively influenced individuals' perceptions of their neighbourhoods, potentially shaping their walking habits and comfort levels. According to Bandura's social cognitive theory (1986) (Sallis et al., 2015), the built environment shapes behaviour through both perceptions and sensations, making the perceived quality of the neighbourhood as crucial as its objective characteristics.

The results of this study demonstrate that neighbourhood characteristics such as land-use mix, retail density, and street connectivity are crucial determinants of walkability and outdoor thermal comfort. Urban planners and policymakers should consider these characteristics in future urban development projects, particularly in hot-arid climates like Buraydah City. Enhancing shaded areas, creating mixed-use neighbourhoods, and designing connected streets can potentially increase physical activity levels while improving thermal comfort.

The study presents valuable insights for future urban planning and policy. Creating walkable neighbourhoods in regions with extreme climates involves balancing thermal comfort and accessibility. Enhancing shade through tree planting or infrastructure and encouraging mixed-use development can promote comfort and walkability. Although this study offers important findings, there are opportunities for further research. Longitudinal studies could help reveal how walkability and thermal comfort improvements impact walking behaviour over time. Additionally, incorporating objective measures of walking activity and detailed microclimatic assessments could provide a more comprehensive understanding, reducing potential biases from self-reported data.

The study’s findings, while relevant to cities in hot-arid climates like Buraydah, should be interpreted with caution when applied to different climatic regions or urban morphologies. The environmental and urban characteristics specific to Buraydah City influenced pedestrian behaviour and thermal comfort, particularly regarding high summer temperatures and limited green infrastructure. We suggest that future research could extend these findings to cities with varying climates and urban forms to assess the broader applicability of the study conclusions. This approach could provide a more holistic understanding of walkability and thermal comfort across diverse urban environments.

This study provides valuable insights into the relationships between neighbourhood walkability, thermal comfort, and pedestrian behaviour in Buraydah City, Saudi Arabia. It enhances understanding of the built environment's objective and perceived characteristics that encourage walking. As one of the first studies in a hot-arid region examining adults' daily walking in relation to outdoor thermal comfort using PET, it underscores the significant impact of neighbourhood design and microclimate characteristics on walking behaviour and thermal comfort levels.

The findings demonstrate that residents of high-walkable neighbourhoods walk more frequently and experience greater thermal comfort than those in low-walkable neighbourhoods, highlighting the benefits of walkable urban environments. Enhancing characteristics such as residential density, land-use intensity, and retail density in low-walkable neighbourhoods is recommended to encourage more walking and improve comfort. Effective microclimate management—such as creating shaded streets through compact developments—plays a crucial role in mitigating urban heat effects, thereby supporting more walkable and livable communities in hot climates. These findings are crucial for urban planners and policymakers to create more sustainable and livable environments, especially in hot-arid climates like Buraydah City.

The study highlights the need for tailored urban planning and design. Low-walkable neighbourhoods could benefit from mixed-use developments, while high-walkable neighbourhoods might be enhanced by adding more green spaces. Urban design principles prioritising walkability and thermal comfort can promote healthier lifestyles. Future research should examine the impact of neighbourhood characteristics, socioeconomic factors, and seasonal variations on walking behaviour using longitudinal studies and advanced tools like GIS and remote sensing.

The abstract of this paper was presented at the Urban Planning & Architectural Design for Sustainable Development (UPADSD) Conference – 9th Edition, which was held on the 22^nd – 24^th of October 2024.