تقييم ونمذجة مؤشرات الاستدامة لشبكة الطرق الحضرية في مدينة كربلاء كدراسة حالة

Evaluating and Modeling the Sustainability Indicators for Urban Road Network: Karbala City as A Case Study

Abstract
The study presents a comprehensive, multidisciplinary, and context-sensitive assessment of urban transportation sustainability in Karbala City, Iraq. It aims to address the complex challenges facing urban mobility in rapidly developing cities by formulating a robust and adaptable analytical framework that integrates the environmental, social, and economic pillars of sustainability. In doing so, it bridges critical gaps in existing evaluation models, which often fail to account for the socio-spatial and infrastructural complexities of cities in the Global South.
To achieve its objectives, a multi-method approach was employed, combining the Analytic Hierarchy Process (AHP), Fuzzy Logic, and Geographic Information Systems (GIS). This methodological approach enabled the development of a flexible Multi-Criteria Decision-Making (MCDM) model capable of quantifying the sustainability performance of Karbala’s urban road network in both spatial and conceptual dimensions. The work began with an extensive literature review encompassing 197 scholarly sources, from which 33 sustainability indicators were identified and systematically classified under environmental, social, and economic categories.
The case study focused on 18 major intersections and urban corridors within the central region of Karbala, particularly areas linking the Central Business District (CBD) with high-density residential, commercial, and institutional zones. Primary data were collected during peak traffic hours across three consecutive weekdays in October 2023. These data included vehicle counts, travel times, road geometry, accident rates, and environmental measurements such as noise levels and air pollutant concentrations. Advanced instrumentation, such as the GASMET DX4040 FTIR gas analyzer, was utilized to monitor pollutants including CO₂, NO₂, SO₂, CH₄, NH₃, and benzene, providing real-time and high-accuracy environmental assessments.
Topological and geometrical analysis revealed that the road network, especially within the CBD, exhibits a fragmented, tree-like morphology characterized by low Alpha, Beta, and Gamma indices, as well as poor Relative Neighbourhood Graph (RNG) connectivity. These structural deficiencies result in poor accessibility, weak interconnectivity, and minimal route redundancy, ultimately undermining the resilience and efficiency of the transportation system.
Modal split analysis indicated a significant reliance on private vehicles, which accounted for 73% of peak-hour traffic, whereas buses and minibuses represented only 6% and 21%, respectively. This imbalance exacerbates congestion, increases travel delays, and raises operational and environmental costs. Notably, noise pollution levels in critical corridors such as Al-Tarbiya exceeded 107 dBA, far surpassing internationally accepted thresholds set by the WHO, CPCB, and EPA. Concurrently, air quality analysis demonstrated elevated concentrations of harmful pollutants, posing serious public health risks to residents, particularly in densely populated and poorly ventilated urban zones.
The sustainability evaluation using AHP revealed that environmental indicators held the highest significance, with a weight of 48.95%, followed by social (28.84%) and economic (22.22%) criteria. Overall sustainability scores across the study locations ranged between 29% and 39%, signaling widespread underperformance and the urgent need for targeted interventions.
To assess Karbala’s performance against global benchmarks, a comparative analysis was conducted with international sustainability frameworks, including LEED (Leadership in Energy and Environmental Design), Green Star, CASBEE (Comprehensive Assessment System for Built Environment Efficiency), GSAS (Global Sustainability Assessment System), and BREEAM Communities. Except for BREEAM Communities, which showed passing ratings for all selected locations, the city’s road network failed to meet the minimum thresholds required by other frameworks. This highlights the necessity for context-sensitive and locally adaptable assessment tools that better align with the conditions of developing cities.
GIS-based spatial modeling played a crucial role in visualizing and analyzing traffic dynamics, congestion hotspots, and environmental stress zones. These spatial outputs also enabled the identification of high-potential corridors for strategic development and sustainable infrastructure investment. However, several practical constraints to implementation were noted, including land tenure conflicts, inadequate municipal funding, institutional inertia, and resistance from local communities.
The research advocates for a paradigm shift in urban transportation planning, moving from fragmented and reactive approaches to integrated, forward-looking strategies grounded in sustainability. It emphasizes the importance of inclusive policy-making, data-driven decision support systems, and long-term planning frameworks that align with both local needs and global development agendas. The proposed framework is tailored to Karbala’s urban fabric yet remains scalable and replicable, offering valuable insights for cities across the Global South facing similar developmental and environmental challenges.
In sum, the thesis contributes a novel and holistic sustainability assessment model that integrates scientific rigor with practical relevance. It equips urban planners, engineers, and decision-makers with tools to evaluate, design, and implement sustainable mobility solutions that enhance resilience, equity, and quality of life in complex urban environments.