Simulation Based Analysis of the Hierarchical Timed Coloured Petri Net Model for Automobile Maintenance Service Centre

Automobile maintenance service centres operate as complex discrete-event systems in which multiple maintenance activities are executed concurrently while competing for limited service resources. Inefficient scheduling, prolonged vehicle waiting time, queue congestion, and poor resource utilization continue to reduce service efficiency and customer satisfaction. Although Hierarchical Timed Coloured Petri Nets (HTCPNs) have demonstrated considerable capability for modelling concurrent systems, limited studies have investigated their application to the simulation and performance evaluation of automobile maintenance service centres involving both engine servicing and running repairs. This study presents the simulation of an HTCPN model developed for an automobile maintenance service centre using DDD Motors Service Centre as a case study. Operational data comprising vehicle arrivals, service commencement times, service completion times, and maintenance categories were collected over one month and analysed using the ARENA Input Analyzer to determine stochastic input distributions. The HTCPN model was implemented in CPN Tools and simulated under five operational scenarios representing different resource allocation policies. System performance was evaluated using six performance indicators: Vehicle Average Waiting Time (VAWT), Vehicle Average Service Time (VAST), Vehicle Average Time of Stay (VAST/TOS), Vehicle Average Queue Number (VAQN), Average Serviced Vehicles (ASV), and Average Leftover Vehicles (ALOV). The simulation results indicate progressive improvement in operational performance across the scenarios. Scenario 5 produced the lowest VAWT (4.02 min), VAST (122.17 min), VAST/TOS (126.19 min), VAQN (10.22), and ALOV (1), while increasing ASV to 41 vehicles. Statistical validation using an independent-samples t-test revealed no significant difference between simulated and observed serviced vehicles (p = 0.618), confirming the validity of the simulation model. The study demonstrates that HTCPN simulation provides an effective decision-support framework for evaluating alternative operational policies and improving service efficiency in automobile maintenance service centres.

Keywords: Automobile maintenance, Hierarchical Timed Coloured Petri Nets, Simulation, CPN Tools, Service operations, Discrete-event systems. Scenario Analysis.