Optimal bus transit system considering service network design and route packaging

Bus transportation is one of the most important means of public transportation in today’s world. All major transit regulators intend to improve the bus operation such that the system functions sustainably with respect to all stakeholders involved viz. authority, operators and the commuters. On a day-to-day basis, several improvements are implemented using consumer satisfaction indices or parameters that are critical and need immediate attention. However, a systematic bus transit system design requires an analytical framework for rational decision making such that the transit network serves the maximum number of commuters at their desired level of service while being financially sustainable for the operators and the regulator. In this study, the mathematical modelling technique is employed to propose strategies for a financially and socially sustainable bus transportation system using the mathematical programming (optimization) approach. A set of problems addressing two important aspects of bus transit operation viz. service/network design and regulatory framework design involving different stakeholders are discussed which represent a diverse range of analytical problems faced by the bus transit industry today. In the first section of the thesis, problems relating to transit network design are discussed which act as analytical interfaces between the operators and the commuters; helping the operator to come up with optimal strategies in terms of service network design and tackle issues of congestion. Specifically, a comprehensive design of limited stop service is proposed using the deterministic and stochastic user equilibrium. Further, a bus transit network design problem is proposed to include congestion effects and derive optimal strategies of travel on common lines out of a set of lines serving the transit network. In the second section of the thesis, problems relating to transit network and regulatory framework design of bus transit are discussed with respect to the government contracting regime. A few major bus transit friendly cities recently adopted this regime wherein the government/authority owns all infrastructure and tenders out transit route packages (sets of routes) to private transit players through competitive tendering only for routine operation and maintenance. This thesis presents a detailed mathematical modelling framework of the government contracting regime based on two aspects (i) bus transit route packaging and (ii) competitive tendering of transit route packages to contesting operators. For each of the mathematical models developed, detailed solution algorithms are developed in order to reformulate, linearize and subsequently convexify the formulation to solve it to global optimality. Various mathematical techniques including linearization for the product of binary variables, reformulation-linearization technique, single and multi-dimensional piecewise linearization method and linear piece-wise approximation method are used in the thesis to propose the solution methodology. Thereafter, the mathematical models are validated on real-time transit networks, and results obtained are discussed with some more discussions. To conclude, all the model formulations developed in this thesis present a comprehensive decision making framework for a sustainable bus transit system in the long run. Addressing transit network design and the transit regulatory /policy issues, the proposed framework of analytical models in totality would certainly provide transit planners with a good insight into equitable methods of transit operation to promote social welfare.Doctor of Philosophy (CEE