Introducing heterogeneous users and vehicles into models and algorithms for the dial-a-ride problem.

Area of Science:

• Operations Research
• Transportation Science
• Logistics Management

Background:

• Dial-a-ride problems involve transporting passengers with service constraints like time windows.
• Real-world applications often feature diverse user needs and vehicle types, particularly in specialized transport.

Purpose of the Study:

• To extend standard dial-a-ride problem formulations and algorithms.
• To integrate multi-modal transportation (staff, patient, stretcher, wheelchair) and heterogeneous vehicle fleets.
• To analyze vehicle waiting times with passengers.

Main Methods:

• Introduced multi-modal user requirements and diverse vehicle types into existing dial-a-ride problem formulations.
• Adapted state-of-the-art branch-and-cut algorithms and a metaheuristic method.
• Analyzed vehicle waiting time as a service quality metric.

Main Results:

• Successfully solved instances with up to 40 requests to optimality.
• Achieved high-quality solutions using the adapted metaheuristic method.
• Demonstrated the effectiveness of the enhanced models for complex transportation scenarios.

Conclusions:

• The enhanced dial-a-ride models effectively address multi-modal transport and varied vehicle fleets.
• Optimized algorithms provide efficient solutions for challenging patient and disabled transportation logistics.
• The study offers practical improvements for service quality in specialized transport operations.