Andrzej Adamski

Simulation support tool for real-time dispatching control in public transport

In practice punctuality of transit service has been a chronic operational problem mainly due to the random environment and very high complexity of the public transport processes. This challenging problem affects both travellers (reliability of service) as well as operators (productivity and efficiency of resources utilization). The potential of new information and communication technologies and existing hardware possibilities offer great opportunities for the development of effective and flexible management and control tools for public transport. In this paper the simulation decision-support tool for dynamic optimal dispatching control purposes have been developed, with the use of the SIMULINK package with Toolboxes. The following optimal dispatching control problems have been solved: punctuality control (which compensates deviations from schedule), regularity control (which compensates deviations from regular headway) and synchronizing control with linear (LQ, dead-beat) feedback and control and system state constraints; LQG stochastic control with real-time estimation of the model parameters; and bus route zone control for synchronising passenger transfers or the operation of different lines on common segments of the route. The results presented are illustrated by 15 numerical examples.

Probabilistic models of passengers service processes at bus stops

Stop time variability in bus operation is known to be very often the dominant factor which influences bunching. The aim of this paper is to study in detail the main stochastic factors which affect the times spent by buses at stops. For this purpose various realistic random representations for main determinants of the parallel and series passengers service processes at bus stops are chosen. New analytical expressions for density functions and moments of the stop time random variable are derived. The results have been tested on data from a real bus route.

Flexible Dispatching Control Tools in Public Transport

In the public transport transit on-time service has been a chronic operational problem created by the existence of unpredictable operational random events and high complexity of the public transport processes. The potential of new information and communication technologies offers great opportunities for the development of effective management and control tools for improvement of transit service reliability. This paper focuses on the distributed dispatching control problem, embedded into the follow-up direct control layer in the hierarchical control system. Autonomous dispatching control actions are practically realized by vehicles equipped with on-board computers and some communication media. In the paper wide spectrum of flexible single and multicriteria dispatching control tools are presented. Different control criteria described in terms of waiting time and control random variables moments are used as service irregularity and control cost measures. The analytical solutions for various types of non-linear regulators (half-wave rectifier, relay, polynomial, flexible with insensitivity zone) and various types of dispatching control strategies are presented and numerically illustrated.

Optimal dispatching control of bus lines

Abstract In the paper a multilevel control system for public transport is presented. Special attention is given to the bottom DDC level realizing real time dispatching control. It is based on the Automatic Vehicle Monitoring / AVM / system which gives the repetitive feedback. The dispatching control ensures that the system state tracks the given time - table / punctuality control / or regular headway / regularity control /. A discrete control model describing the fundamental phenomena observed during the movement of buses is proposed. Bunching of buses has been analysed in detail because it degrades service and operating efficiency. The DDC level is divided into two layers. The lower one acts as a discrete regulator, optimal in the L-Q or L-Q-G sense. The upper layer realizes repetitive control by selecting or generating actual modification of the schedule which yields the pattern for the discrete regulator. Different kinds of bus dispatching control strategies / holding, priority control at intersections, reserve, overtaking, curtailment / can be realized in the proposed model. It is expected that the implementation of the results of the paper in real-life bus dispatching control based on AVM system will improve its performance.

Optimal Service Synchronization in Public Transport

Abstract In this paper two schedule synchronization problems in public transit network are formulated and solved. The first is concerned with a transfer synchronization when passengers changing transit lines at transfer points. The stochastic version of QSAP (Quadratic Semi-Assignment Problem) formulation is developed together with the efficient computer solution method. The second is concerned with the headways harmonization problem i.e. synchronization of different transit lines on a common segment of routes. Illustrative real-life bus lines examples demonstrate the utility of these two proposals.

ROUTING PROBLEMS BASED ON HILS SYSTEM PLATFORM

Background: The logistic systems are very complex socio-technic al systems. In this paper the proposal of application of the hierarchical multi-layers sys tem platform HILS approach for the solution of the complex vehicle routing problems is presented. The interactive syst em functional structure was proposed which by intel ligent dedicated inter-layers interactions enables the professional solutions of these practical problems. To illustrat e these capabilities the complex example of the real-time VRP-SPD-TW routing problem was presented in which upper layers offers the context-related real-time updating network specific ations that stimulates the adequate routing paramet ers and specifications updating for problem solution in opt imization layer. At the bottom dispatching control layer the DISCON (Dispatching CONtrol) method from public transport was adopted to logistics applications in which the a ctual routing is treated as obligatory reference schedule to be stab ilized. The intelligence aspects are related among others to HILS based decomposition, context-related trade-offs between r outing modifications and corrective dispatching con trol capabilities e.g. priority or route guidance actions. Methods: Decomposition of the vehicle routing problem for t he HILS layers tasks creating the ILS system hierar chical structure. Dedicated solution method for the VRP-SP D-TW routing problem. The recognition of the control preferences structure by AHP-Entropy methods. DISCON and PIACON multi-criteria interacting control methods. Results: Original formulation and solution of the vehicle r outing problem by system-wide approach with essential practical advantages: consistency, lack of redundan cy, essential reduction of dimension, dedicated for mulation, multi- criteria approach, exploration of the integration a nd intelligence features supported by the intellige nt PIACON-DISCON methods control activities Conclusions: The presented proposal creates the professional ap proach to the solution of the crucial problems in l ogistics systems with the implementation of modern tools and enabling technologies.

OPTIMAL DISPATCHING CONTROL OF BUS LINES

In the paper a multilevel control system for public transport is presented. Special attention is given to the bottom DDC level realizing real time dispatching control. It is based on the Automatic Vehicle Monitoring/AVM/system which gives the repetitive feedback. The dispatching control ensures that the system state tracks the given time - table/punctuality control/or regular headway/regularity control /. A discrete control model describing the fundamental phenomena observed during the movement of buses is proposed. Bunching of buses has been analysed in detail because it degrades service and operating efficiency. The DDC level is divided into two layers. The lower one acts as a discrete regulator, optimal in the L-Q or L-Q-G sense. The upper layer realizes repetitive control by selecting or generating actual modification of the schedule which yields the pattern for the discrete regulator. Different kinds of bus dispatching control strategies/holding, priority control at intersections, reserve, overtaking, curtailment/can be realized in the proposed model. It is expected that the implementation of the results of the paper in real-life bus dispatching control based on AVM system will improve its performance.