A Review of the Redesign of Public Bus Network Routes in Iraqi Cities: A Framework Driven by Theory with a Case Study of a Mid-Size City

Abstract

This review paper lays the theoretical foundations for redesigning public bus route networks in mid-sized Iraqi cities, with the Mid-Size City case serving as a near-future exemplification. We integrate TRNDP decision/constraint/objective structures with replicable, GTFS-based diagnostics – L-space, P-space, and route-space – to interpret transfer exposure, redundancy, and corridor coherence. Compact performance components – including expected waiting time, dwell time, commercial speed, cycle time, capacity, and accessibility – provide a concise KPI package suitable for door-to-door assessment and equity declaration. We propose that frequency-first trunks, a rational stop policy, conditional TSP, and proof-of-payment/all-door boarding constitute a practical mix for conventional buses under budget and ROW constraints. A GTFS-native pipeline produces auditable scenario packs, including a baseline, a limited-stop route, a trunk-feeder network with timed transfers, and frequency optimization under a fleet cap, along with standardized KPIs. This sets the foundation for an in-person test on Mid-Size City’s Streets 40 and 60. We have decided to make Mid-Size City our proof-of-concept application domain based on two broad categories of consideration.

Introduction

The text examines the challenges and opportunities of redesigning public bus transit systems in mid-sized Iraqi cities facing rising travel demand, congestion, limited budgets, and weak data and institutional frameworks. Rapid growth in private vehicle ownership has reduced travel reliability, safety, and environmental quality, highlighting the urgent need to upgrade bus networks as a cost-effective and scalable mobility solution. The study adopts a theory-first, policy-oriented approach aligned with the SSATP framework (Enable, Avoid, Shift, Improve) to guide bus network design under data and resource constraints typical of developing cities.

Public transport design is presented as a multi-level process encompassing strategic decisions (route topology, hierarchy, interchange roles), tactical decisions (stop spacing, frequencies, timed transfers), and operational considerations (schedule reliability and control). These decisions are formalized through the Transit Route Network Design Problem (TRNDP), a multi-objective optimization framework that balances passenger travel time, agency costs, equity, accessibility, and sustainability. The paper proposes standardized GTFS-based data structures, transparent analytics, and performance indicators to support replicable and auditable decision-making.

Focusing primarily on conventional buses due to local constraints, the background review traces the historical evolution of public transport and emphasizes the role of buses as the backbone of urban mobility in developing contexts. In the case study area, key arterial corridors experience heavy congestion due to rapid urban growth, land-use intensification, and poor modal integration, reinforcing the need for systematic bus network redesign.

The text highlights the advantages of conventional buses, including flexibility, low capital cost, rapid deployment, health benefits from access walking, and potential efficiency gains from improved boarding practices and selective transit priority. At the same time, it notes challenges such as boarding delays, reliability issues in mixed traffic, and design trade-offs related to stop spacing and passenger waiting times.

Overall, the study argues that disciplined bus network redesign—using clear objectives, robust evaluation metrics, and simple, legible service patterns—offers a high-impact, realistic pathway to improve mobility, equity, and environmental performance in mid-sized Iraqi cities despite significant data, budgetary, and institutional limitations.

Conclusion

This review assembles a theory-driven framework for bus network redesign and translates it into a reproducible, GTFS-backed workflow. By linking design levers—such as routes, frequency, stop spacing/placement, timed transfers, boarding method, and signal priority—to measurable mechanisms and outcomes, it provides a practical toolkit for agencies operating under tight budgets and mixed-traffic conditions. The KPI pack and equity-aware accessibility elevate reporting from anecdote to evidence. The framework is ready for empirical deployment in a mid-sized City, focusing on Streets in the city center with short feeders, and will be evaluated through scenario-based GTFS and standardized KPIs.

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Copyright © 2026 Zaid Ahmed Shakir, Ali Fadhil Naser. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.