Conference Agenda

Despite Thailand’s substantial investments in rail infrastructure over the past decade, the freight modal shift from road to rail remains severely limited. As of 2024, rail freight accounts for less than 2% of total cargo volume, while road transport continues to dominate nearly 80% of the national logistics system. This Chronic imbalance drive persistent logistics inefficiencies, traffic congestion, rapid infrastructure deterioration, severe environmental externalities, and inflated supply chain costs. Traditional modal shift research relies on static econometrics or optimization models, such as discrete choice logit / probit or optimization models, that fail to capture the endogenous feedback mechanisms, infrastructure degradation cycles, and stakeholder behavioral delays inherent to transport systems. Consequently, these static approaches are unable to demonstrate the long-term, dynamic evaluation of freight transport systems, risking suboptimal policy recommendations.

This study develops a System Dynamics framework to integrate the complex, time-dependent interactions between road and rail freight transport. The proposed model evaluates modal choice behavior, generalized transport costs, operational capacity, congestion, infrastructure investment deterioration within a unified dynamic system driven by policy feedback loops. Notably, the framework incorporates perception delays through perceived generalized costs to reflect the gradual behavioral shift of freight operators and shippers

The framework was initially calibrated using data from the strategic Northeastern–Eastern Thailand freight corridor that connects inland production hubs to Laem Chabang Port. The model simulates the long-term interactions among freight demand, traffic congestion, infrastructure performance, rail utilization, terminal handling delays, and maintenance cycles. In particular, the study emphasizes the joint role of externalities internalization policies (such as truck enforcement and road pricing measures) and rail infrastructure enhancements (including capacity expansion, terminal development, and service quality upgrades). This framework enables a rigorous analysis of policy coordination, execution timing and latent capacity bottlenecks.

Preliminary simulation results demonstrate that rail infrastructure investment alone is insufficient to induce a substantial modal shift if road transport externalities remain underpriced. Conversely, road enforcement policies alone increase overall logistics costs if rail networks lack the capacity to absorb the shifting freight demand. Effective modal shift emerges from coordinated policy combinations implemented under appropriate timing conditions. Furthermore, the model reveals highly dynamic system behaviors, including nonlinear modal transitions, supply-chain spill-back effects from rail capacity shortage, balancing feedback from terminal congestion, and long-term reductions in road deterioration and congestion. Ultimately, this research introduces an integrated dynamic policy-feedback framework that unifies modal competition, infrastructure degradation, externalities, and transport system performance within a single endogenous system. The proposed framework serves as a robust policy simulation tool for evaluating sustainable freight transport strategies in developing economies.